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Sample records for aspartic acid residues

  1. Critical aspartic acid residues in pseudouridine synthases.

    Science.gov (United States)

    Ramamurthy, V; Swann, S L; Paulson, J L; Spedaliere, C J; Mueller, E G

    1999-08-01

    The pseudouridine synthases catalyze the isomerization of uridine to pseudouridine at particular positions in certain RNA molecules. Genomic data base searches and sequence alignments using the first four identified pseudouridine synthases led Koonin (Koonin, E. V. (1996) Nucleic Acids Res. 24, 2411-2415) and, independently, Santi and co-workers (Gustafsson, C., Reid, R., Greene, P. J., and Santi, D. V. (1996) Nucleic Acids Res. 24, 3756-3762) to group this class of enzyme into four families, which display no statistically significant global sequence similarity to each other. Upon further scrutiny (Huang, H. L., Pookanjanatavip, M., Gu, X. G., and Santi, D. V. (1998) Biochemistry 37, 344-351), the Santi group discovered that a single aspartic acid residue is the only amino acid present in all of the aligned sequences; they then demonstrated that this aspartic acid residue is catalytically essential in one pseudouridine synthase. To test the functional significance of the sequence alignments in light of the global dissimilarity between the pseudouridine synthase families, we changed the aspartic acid residue in representatives of two additional families to both alanine and cysteine: the mutant enzymes are catalytically inactive but retain the ability to bind tRNA substrate. We have also verified that the mutant enzymes do not release uracil from the substrate at a rate significant relative to turnover by the wild-type pseudouridine synthases. Our results clearly show that the aligned aspartic acid residue is critical for the catalytic activity of pseudouridine synthases from two additional families of these enzymes, supporting the predictive power of the sequence alignments and suggesting that the sequence motif containing the aligned aspartic acid residue might be a prerequisite for pseudouridine synthase function.

  2. Acetic Acid Can Catalyze Succinimide Formation from Aspartic Acid Residues by a Concerted Bond Reorganization Mechanism: A Computational Study

    Directory of Open Access Journals (Sweden)

    Ohgi Takahashi

    2015-01-01

    Full Text Available Succinimide formation from aspartic acid (Asp residues is a concern in the formulation of protein drugs. Based on density functional theory calculations using Ace-Asp-Nme (Ace = acetyl, Nme = NHMe as a model compound, we propose the possibility that acetic acid (AA, which is often used in protein drug formulation for mildly acidic buffer solutions, catalyzes the succinimide formation from Asp residues by acting as a proton-transfer mediator. The proposed mechanism comprises two steps: cyclization (intramolecular addition to form a gem-diol tetrahedral intermediate and dehydration of the intermediate. Both steps are catalyzed by an AA molecule, and the first step was predicted to be rate-determining. The cyclization results from a bond formation between the amide nitrogen on the C-terminal side and the side-chain carboxyl carbon, which is part of an extensive bond reorganization (formation and breaking of single bonds and the interchange of single and double bonds occurring concertedly in a cyclic structure formed by the amide NH bond, the AA molecule and the side-chain C=O group and involving a double proton transfer. The second step also involves an AA-mediated bond reorganization. Carboxylic acids other than AA are also expected to catalyze the succinimide formation by a similar mechanism.

  3. Mutation of aspartic acid residues in the fructosyltransferase of Streptococcus salivarius ATCC 25975.

    Science.gov (United States)

    Song, D D; Jacques, N A

    1999-01-01

    The site-directed mutated fructosyltransferases (Ftfs) of Streptococcus salivarius ATCC 25975, D312E, D312S, D312N and D312K were all active at 37 degrees C, indicating that Asp-312 present in the 'sucrose box' was not the nucleophilic Asp residue responsible for the formation of a covalent fructosyl-enzyme intermediate required for enzyme activity. Analysis of the kinetic constants of the purified mutated forms of the enzyme showed that Asp-312 was most likely an essential amino acid involved in determining acceptor recognition and/or stabilizing a beta-turn in the protein. In contrast, when the Asp-397 of the Ftf present in the conserved triplet RDP motif of all 60 bacterial and plant family-32 glycosylhydrolases was mutated to a Ser residue, both sucrose hydrolysis and polymerization ceased. Tryptophan emission spectra confirmed that this mutation did not alter protein structure. Comparison of published data from other site-directed mutated enzymes implicated the Asp residue in the RDP motif as the one that may form a transient covalent fructosyl intermediate during the catalysis of sucrose by the Ftf of S. salivarius. PMID:10548559

  4. Cavity residue leucine 95 and channel residues glutamine 204, aspartic acid 211, and phenylalanine 269 of toluene o-xylene monooxygenase influence catalysis.

    Science.gov (United States)

    Kurt, Cansu; Sönmez, Burcu; Vardar, Nurcan; Yanık-Yıldırım, K Cansu; Vardar-Schara, Gönül

    2016-09-01

    Structural analysis of toluene-o-xylene monooxygenase (ToMO) hydroxylase revealed the presence of three hydrophobic cavities, a channel, and a pore leading from the protein surface to the active site. Here, saturation mutagenesis was used to investigate the catalytic roles of alpha-subunit (TouA) second cavity residue L95 and TouA channel residues Q204, D211, and F269. By testing the substrates toluene, phenol, nitrobenzene, and/or naphthalene, these positions were found to influence the catalytic activity of ToMO. Several regiospecific variants were identified from TouA positions Q204, F269, and L95. For example, TouA variant Q204H had the regiospecificity of nitrobenzene changed significantly from 30 to 61 % p-nitrophenol. Interestingly, a combination of mutations at Q204H and A106V altered the regiospecificity of nitrobenzene back to 27 % p-nitrophenol. TouA variants F269Y, F269P, Q204E, and L95D improved the meta-hydroxylating capability of nitrobenzene by producing 87, 85, 82, and 77 % m-nitrophenol, respectively. For naphthalene oxidation, TouA variants F269V, Q204A, Q204S/S222N, and F269T had the regiospecificity changed from 16 to 9, 10, 23, and 25 % 2-naphthol, respectively. Here, two additional TouA residues, S222 and A106, were also identified that may have important roles in catalysis. Most of the isolated variants from D211 remained active, whereas having a hydrophobic residue at this position appeared to diminish the catalytic activity toward naphthalene. The mutational effects on the ToMO regiospecificity described here suggest that it is possible to further fine tune and engineer the reactivity of multicomponent diiron monooxygenases toward different substrates at positions that are relatively distant from the active site. PMID:27311562

  5. Identification of glutamic acid 204 and aspartic acid 200 in chitinase A1 of Bacillus circulans WL-12 as essential residues for chitinase activity.

    Science.gov (United States)

    Watanabe, T; Kobori, K; Miyashita, K; Fujii, T; Sakai, H; Uchida, M; Tanaka, H

    1993-09-01

    Prokaryotic chitinases, class III plant chitinases, yeast chitinases, and endo-beta-N-acetylglucosaminidases share weak amino acid sequence similarities at the certain region of each enzyme. These regions have been assumed to be important for catalytic activities of the enzymes. To verify this assumption, three amino acid residues (Ser-160, Asp-200, Glu-204) in chitinase A1 of Bacillus circulans WL-12 were chosen, based on the amino acid sequence alignment of the regions sharing sequence similarity, and were replaced by site-directed mutagenesis. Kinetic parameters for 4-methylumbelliferyl-N,N',N"-triacetylchitotriose hydrolysis were determined with wild-type and seven mutant chitinases. Chitinases with Glu-204-->Gln mutation and Glu-204-->Asp mutation were essentially inactive and kcat values of these chitinases were approximately 1/5,000 and 1/17,000 of that of wild-type chitinase, respectively. Asp-200-->Asn mutation decreased the kcat value to approximately 1/350 of that of the wild-type enzyme, while the Km value decreased only slightly. On the other hand, neither the kcat value nor the Km value was affected by Asp-200-->Glu mutation. Thus, it appeared that Glu-204 and Asp-200 are directly involved in the catalytic events of chitinase A1. The role of the carboxyl group of Asp-200 can be fully substituted by that of Glu residue. The Ser-160-->Ala mutant retained 10% activity of the wild-type chitinase indicating that the hydroxyl group of Ser-160 is not absolutely required for the catalytic activity. These results indicate a lysozyme-type catalytic mechanism of the chitinase.

  6. Prediction of binding modes between protein L-isoaspartyl (D-aspartyl) O-methyltransferase and peptide substrates including isomerized aspartic acid residues using in silico analytic methods for the substrate screening.

    Science.gov (United States)

    Oda, Akifumi; Noji, Ikuhiko; Fukuyoshi, Shuichi; Takahashi, Ohgi

    2015-12-10

    Because the aspartic acid (Asp) residues in proteins are occasionally isomerized in the human body, not only l-α-Asp but also l-β-Asp, D-α-Asp and D-β-Asp are found in human proteins. In these isomerized aspartic acids, the proportion of D-β-Asp is the largest and the proportions of l-β-Asp and D-α-Asp found in human proteins are comparatively small. To explain the proportions of aspartic acid isomers, the possibility of an enzyme able to repair l-β-Asp and D-α-Asp is frequently considered. The protein L-isoaspartyl (D-aspartyl) O-methyltransferase (PIMT) is considered one of the possible repair enzymes for l-β-Asp and D-α-Asp. Human PIMT is an enzyme that recognizes both l-β-Asp and D-α-Asp, and catalyzes the methylation of their side chains. In this study, the binding modes between PIMT and peptide substrates containing l-β-Asp or D-α-Asp residues were investigated using computational protein-ligand docking and molecular dynamics simulations. The results indicate that carboxyl groups of both l-β-Asp and D-α-Asp were recognized in similar modes by PIMT and that the C-terminal regions of substrate peptides were located in similar positions on PIMT for both the l-β-Asp and D-α-Asp peptides. In contrast, for peptides containing l-α-Asp or D-β-Asp residues, which are not substrates of PIMT, the computationally constructed binding modes between PIMT and peptides greatly differed from those between PIMT and substrates. In the nonsubstrate peptides, not inter- but intra-molecular hydrogen bonds were observed, and the conformations of peptides were more rigid than those of substrates. Thus, the in silico analytical methods were able to distinguish substrates from nonsubstrates and the computational methods are expected to complement experimental analytical methods.

  7. Effects of mutagenesis of aspartic acid residues in the putative phosphoribosyl diphosphate binding site of Escherichia coli phosphoribosyl diphosphate synthetase on metal ion specificity and ribose 5-phosphate binding

    DEFF Research Database (Denmark)

    Willemoës, Martin; Nilsson, Dan; Hove-Jensen, Bjarne

    1996-01-01

    an increase in KM for ribose 5-phosphate in the presence of at least one of the divalent metal ions Mg2+, Mn2+, Co2+, or Cd2+, with the most dramatic changes revealed by the D220E and D220F enzymes in the presence of Co2+ and the D221A enzyme in the presence of Mn2+ or Co2+. The D220F and D221A enzymes both...... showed large decreases in Vapp in the presence of the various divalent metal ions, except for the D221A enzyme in the presence of Co2+. Vapp of the D220E enzyme was similar to that of the wild-type enzyme in the presence of Mg2+, Mn2+, or Cd2+, whereas the Vapp was increased in the presence of Co2+. Vapp...... enzymes were dependent on the metal ion present, suggesting a function of the investigated aspartic acid residues both in the binding of ribose 5-phosphate, possibly via a divalent metal ion, and in the interaction with a divalent metal ion during catalysis...

  8. Effects of mutagenesis of aspartic acid residues in the putative phosphoribosyl diphosphate binding site of Escherichia coli phosphoribosyl diphosphate synthetase on metal ion specificity and ribose-5-phosphate binding

    DEFF Research Database (Denmark)

    Willemoës, Martin; Nilsson, Dan; Hove-Jensen, Bjarne

    1996-01-01

    The three conserved aspartic acid residues of the 5-phospho-d-ribosyl a-1-diphosphate binding site (213-GRDCVLVDDMIDTGGT-228) of Escherichia coli phosphoribosyl diphosphate synthetase were studied by analysis of the mutant enzymes D220E, D220F, D221A, D224A, and D224S. The mutant enzymes showed...... an increase in KM for ribose 5-phosphate in the presence of at least one of the divalent metal ions Mg2+, Mn2+, Co2+, or Cd2+, with the most dramatic changes revealed by the D220E and D220F enzymes in the presence of Co2+ and the D221A enzyme in the presence of Mn2+ or Co2+. The D220F and D221A enzymes both...... showed large decreases in Vapp in the presence of the various divalent metal ions, except for the D221A enzyme in the presence of Co2+. Vapp of the D220E enzyme was similar to that of the wild-type enzyme in the presence of Mg2+, Mn2+, or Cd2+, whereas the Vapp was increased in the presence of Co2+. Vapp...

  9. Effects of mutagenesis of aspartic acid residues in the putative phosphoribosyl diphosphate binding site of Escherichia coli phosphoribosyl diphosphate synthetase on metal ion specificity and ribose 5-phosphate binding

    DEFF Research Database (Denmark)

    Willemoës, Martin; Nilsson, Dan; Hove-Jensen, Bjarne

    1996-01-01

    The three conserved aspartic acid residues of the 5-phospho-D-ribosyl α-1-diphosphate binding site (213-GRDCVLVDDMIDTGGT-228) of Escherichia coli phosphoribosyl diphosphate synthetase were studied by analysis of the mutant enzymes D220E, D220F, D221A, D224A, and D224S. The mutant enzymes showed...... an increase in KM for ribose 5-phosphate in the presence of at least one of the divalent metal ions Mg2+, Mn2+, Co2+, or Cd2+, with the most dramatic changes revealed by the D220E and D220F enzymes in the presence of Co2+ and the D221A enzyme in the presence of Mn2+ or Co2+. The D220F and D221A enzymes both...... showed large decreases in Vapp in the presence of the various divalent metal ions, except for the D221A enzyme in the presence of Co2+. Vapp of the D220E enzyme was similar to that of the wild-type enzyme in the presence of Mg2+, Mn2+, or Cd2+, whereas the Vapp was increased in the presence of Co2+. Vapp...

  10. Synthesis of a novel zwitterionic biodegradable poly (α,β-L-aspartic acid) derivative with some L-histidine side-residues and its resistance to non-specific protein adsorption.

    Science.gov (United States)

    Wang, Xiaojuan; Wu, Guolin; Lu, Caicai; Wang, Yinong; Fan, Yunge; Gao, Hui; Ma, Jianbiao

    2011-08-01

    A novel zwitterionic polypeptide derivative, denoted as His-PAsp/PAsp, was successfully synthesized by amidation of Poly (α,β-L-aspartic acid) with L-histidine methyl ester. Turbidity, zeta potential and ¹H NMR measurements were used to study the aggregation behaviors of His-PAsp/PAsp under different pH values. The modified polypeptide derivative composed of electro-negatively carboxylic and electro-positively imidazole residues randomly so as to bear opposite charges at pH values above or below the isoelectric point. When the zwitterionic polypeptide was coated on silicon wafer as a model substrate material, the absorption resistance of fibrinogen, a blood protein resulting in the blood coagulation cascade, on the coated surface was measured. It was found that the adsorption amount of fibrinogen on the polypeptide-coated surface depended on the dose of the polypeptide on silicon wafer. Obvious resistance of the fibrinogen adsorption on the polypeptide-coated surface was observed. Since its good biodegradability and superior anti-protein-fouling property, this pH-responsive zwitterionic polypeptide is a promising candidate for surface modification in many biomedical applications, including medical implants, drug delivery carriers, and biosensors. PMID:21536417

  11. The Reovirus Sigmal Aspartic Acid Sandwich: A Trimerization Motif Poised for Conformational Change

    Energy Technology Data Exchange (ETDEWEB)

    Schelling,P.; Guglielml, K.; Kirchner, E.; Paetzold, b.; Dermody, T.; Stehle, T.

    2007-01-01

    Reovirus attachment protein {sigma}1 mediates engagement of receptors on the surface of target cells and undergoes dramatic conformational rearrangements during viral disassembly in the endocytic pathway. The {sigma}1 protein is a filamentous, trimeric molecule with a globular {beta}-barrel head domain. An unusual cluster of aspartic acid residues sandwiched between hydrophobic tyrosines is located at the {sigma}1 subunit interface. A 1.75 {angstrom} structure of the {sigma}1 head domain now reveals two water molecules at the subunit interface that are held strictly in position and interact with neighboring residues. Structural and biochemical analyses of mutants affecting the aspartic acid sandwich indicate that these residues and the corresponding chelated water molecules act as a plug to block the free flow of solvent and stabilize the trimer. This arrangement of residues at the {sigma}1 head trimer interface illustrates a new protein design motif that may confer conformational mobility during cell entry.

  12. The reovirus sigma1 aspartic acid sandwich: a trimerization motif poised for conformational change.

    Science.gov (United States)

    Schelling, Pierre; Guglielmi, Kristen M; Kirchner, Eva; Paetzold, Bernhard; Dermody, Terence S; Stehle, Thilo

    2007-04-13

    Reovirus attachment protein sigma1 mediates engagement of receptors on the surface of target cells and undergoes dramatic conformational rearrangements during viral disassembly in the endocytic pathway. The sigma1 protein is a filamentous, trimeric molecule with a globular beta-barrel head domain. An unusual cluster of aspartic acid residues sandwiched between hydrophobic tyrosines is located at the sigma1 subunit interface. A 1.75-A structure of the sigma1 head domain now reveals two water molecules at the subunit interface that are held strictly in position and interact with neighboring residues. Structural and biochemical analyses of mutants affecting the aspartic acid sandwich indicate that these residues and the corresponding chelated water molecules act as a plug to block the free flow of solvent and stabilize the trimer. This arrangement of residues at the sigma1 head trimer interface illustrates a new protein design motif that may confer conformational mobility during cell entry.

  13. Superactive insulin: [B10-aspartic acid]insulin(human)

    International Nuclear Information System (INIS)

    The genetic basis for a case of familial hyperproinsulinemia has been elucidated recently. It involves a single point mutation in the proinsulin gene resulting in the substitution of aspartic acid for histidine-10 of the B chain of insulin. The authors have synthesized a human insulin analogue, [Asp/sup B10/] insulin, corresponding to the mutant proinsulin and evaluated its biological activity. [Asp/sup B10/] Insulin displayed a binding affinity to insulin receptors in rat liver plasma membranes that was 534 +- 146% relative to the natural hormone. In lipogenesis assays, the synthetic analogue exhibited a potency that was 435 +- 144% relative to insulin, which is statistically not different from its binding affinity. Reversed-phase HPLC indicated that the synthetic analogue is more apolar than natural insulin. They suggest that the observed properties reflect changes in the conformation of the analogue relative to natural insulin, which results in a stronger interaction with the insulin receptor. Thus, a single substitution of an amino acid residue of human insulin has resulted in a superactive hormone

  14. Superactive insulin: (B10-aspartic acid)insulin(human)

    Energy Technology Data Exchange (ETDEWEB)

    Schwartz, G.P.; Burke, G.T.; Katsoyannis, P.G.

    1987-09-01

    The genetic basis for a case of familial hyperproinsulinemia has been elucidated recently. It involves a single point mutation in the proinsulin gene resulting in the substitution of aspartic acid for histidine-10 of the B chain of insulin. The authors have synthesized a human insulin analogue, (Asp/sup B10/) insulin, corresponding to the mutant proinsulin and evaluated its biological activity. (Asp/sup B10/) Insulin displayed a binding affinity to insulin receptors in rat liver plasma membranes that was 534 +- 146% relative to the natural hormone. In lipogenesis assays, the synthetic analogue exhibited a potency that was 435 +- 144% relative to insulin, which is statistically not different from its binding affinity. Reversed-phase HPLC indicated that the synthetic analogue is more apolar than natural insulin. They suggest that the observed properties reflect changes in the conformation of the analogue relative to natural insulin, which results in a stronger interaction with the insulin receptor. Thus, a single substitution of an amino acid residue of human insulin has resulted in a superactive hormone.

  15. [Application of aspartic acid as a non-specific binding inhibitor in the enrichment of phosphopeptides with titanium dioxide].

    Science.gov (United States)

    Chi, Ming; Bi, Wei; Lu, Zhuang; Song, Lina; Jia, Wei; Zhang, Yangjun; Qian, Xiaohong; Cai, Yun

    2010-02-01

    Titanium dioxide (TiO2) is one of metal oxides widely used for phosphopeptide enrichment in phosphoproteomic research nowadays. However it can bind to some non-phosphorylated peptides containing one or more aspartic acid residues and/or glutamic acid residues. These non-phosphorylated peptides can be eluted along with phosphorylated peptides and cause the reduction of the selectivity. Conventional inhibitors for the non-specific binding of non-phosphorylated peptides can often contaminate the ion source of mass spectrometry and therefore their applications are limited in liquid chromatography-mass spectrometry (LC-MS). In this study, aspartic acid was reported as a novel non-specific binding inhibitor for phosphopeptide enrichment by titanium dioxide. Firstly, the tryptic peptide mixtures of 3 and 9 standard proteins were used for the comparison of the enrichment efficiency of titanium dioxide. The effects with the presence of aspartic acid, glutamic acid and no-inhibitor in the enrichment systems were compared separately. The results showed that aspartic acid can greatly improve the selectivity of titanium dioxide for phosphopeptide enrichment. Then, aspartic acid was used for the enrichment of tryptic peptide mixture of C57BL/6J mouse liver lysate and good results were also obtained which demonstrated that aspartic acid was a promising non-specific binding inhibitor for complex biological samples. Besides, no contamination in the ion source occurred during the mass spectrometric analysis.

  16. Properties of Copolymers of Aspartic Acid and Aliphatic Dicarboxylic Acids Prepared by Reactive Extrusion

    Science.gov (United States)

    Aspartic acid may be prepared chemically or by the fermentation of carbohydrates. Currently, low molecular weight polyaspartic acids are prepared commercially by heating aspartic acid at high temperatures (greater than 220 degrees C) for several hours in the solid state. In an effort to develop a ...

  17. Three-dimensional hybrid networks based on aspartic acid

    Indian Academy of Sciences (India)

    Anupama Ghosh; R A Sanguramath

    2008-01-01

    Three-dimensional achiral coordination polymers of the general formula M2(D, L-NHCH (COO)CH2COO)2.C4H4N2 where M = Ni and Co and pyrazine acts as the linker molecule have been prepared under hydrothermal conditions starting with [M(L-NHCH(COO)CH2COO).3H2O] possessing a helical chain structure. A three-dimensional hybrid compound of the formula Pb2.5[N{CH(COO)CH2COO}22H2O] has also been prepared hydrothermally starting with aspartic acid and Pb(NO3)2. In this lead compound, where a secondary amine formed by the dimerisation of aspartic acid acts as the ligand, there is two-dimensional inorganic connectivity and one-dimensional organic connectivity.

  18. A superactive insulin: [B10-aspartic acid]insulin(human).

    OpenAIRE

    Schwartz, G P; Burke, G. T.; Katsoyannis, P G

    1987-01-01

    The genetic basis for a case of familial hyperproinsulinemia has been elucidated recently. It involves a single point mutation in the proinsulin gene resulting in the substitution of aspartic acid for histidine-10 of the B chain of insulin. We have synthesized a human insulin analogue, [AspB10]insulin, corresponding to the mutant proinsulin and evaluated its biological activity. [AspB10]Insulin displayed a binding affinity to insulin receptors in rat liver plasma membranes that was 534 +/- 14...

  19. The (unusual) aspartic acid in the metal coordination sphere of the prokaryotic zinc finger domain.

    Science.gov (United States)

    D'Abrosca, Gianluca; Russo, Luigi; Palmieri, Maddalena; Baglivo, Ilaria; Netti, Fortuna; de Paola, Ivan; Zaccaro, Laura; Farina, Biancamaria; Iacovino, Rosa; Pedone, Paolo Vincenzo; Isernia, Carla; Fattorusso, Roberto; Malgieri, Gaetano

    2016-08-01

    The possibility of choices of protein ligands and coordination geometries leads to diverse Zn(II) binding sites in zinc-proteins, allowing a range of important biological roles. The prokaryotic Cys2His2 zinc finger domain (originally found in the Ros protein from Agrobacterium tumefaciens) tetrahedrally coordinates zinc through two cysteine and two histidine residues and it does not adopt a correct fold in the absence of the metal ion. Ros is the first structurally characterized member of a family of bacterial proteins that presents several amino acid changes in the positions occupied in Ros by the zinc coordinating residues. In particular, the second position is very often occupied by an aspartic acid although the coordination of structural zinc by an aspartate in eukaryotic zinc fingers is very unusual. Here, by appropriately mutating the protein Ros, we characterize the aspartate role within the coordination sphere of this family of proteins demonstrating how the presence of this residue only slightly perturbs the functional structure of the prokaryotic zinc finger domain while it greatly influences its thermodynamic properties. PMID:27238756

  20. N-methyl-D-aspartic acid receptor agonists

    DEFF Research Database (Denmark)

    Madsen, U; Frydenvang, Karla Andrea; Ebert, B;

    1996-01-01

    (R,S)-2-Amino-2-(3-hydroxy-5-methyl-4-isoxazolyl)acetic acid [(R,S)-AMAA, 4] is a potent and selective agonist at the N-methyl-D-aspartic acid (NMDA) subtype of excitatory amino acid receptors. Using the Ugi "four-component condensation" method, the two diastereomers (2R)- and (2S)-2-[3-(benzyloxy......) showed peak affinity for [3H]AMPA receptor sites (IC50 = 72 +/- 13 microM) and was shown to be a more potent inhibitor of [3H]CPP binding (IC50 = 3.7 +/- 1.5 microM) than (S)-AMAA (9) (IC50 = 61 +/- 6.4 microM). Neither enantiomer of AMAA affected [3H]kainic acid receptor binding significantly...

  1. Structural evidence for solvent-stabilisation by aspartic acid as a mechanism for halophilic protein stability in high salt concentrations.

    Science.gov (United States)

    Lenton, Samuel; Walsh, Danielle L; Rhys, Natasha H; Soper, Alan K; Dougan, Lorna

    2016-07-21

    Halophilic organisms have adapted to survive in high salt environments, where mesophilic organisms would perish. One of the biggest challenges faced by halophilic proteins is the ability to maintain both the structure and function at molar concentrations of salt. A distinct adaptation of halophilic proteins, compared to mesophilic homologues, is the abundance of aspartic acid on the protein surface. Mutagenesis and crystallographic studies of halophilic proteins suggest an important role for solvent interactions with the surface aspartic acid residues. This interaction, between the regions of the acidic protein surface and the solvent, is thought to maintain a hydration layer around the protein at molar salt concentrations thereby allowing halophilic proteins to retain their functional state. Here we present neutron diffraction data of the monomeric zwitterionic form of aspartic acid solutions at physiological pH in 0.25 M and 2.5 M concentration of potassium chloride, to mimic mesophilic and halophilic-like environmental conditions. We have used isotopic substitution in combination with empirical potential structure refinement to extract atomic-scale information from the data. Our study provides structural insights that support the hypothesis that carboxyl groups on acidic residues bind water more tightly under high salt conditions, in support of the residue-ion interaction model of halophilic protein stabilisation. Furthermore our data show that in the presence of high salt the self-association between the zwitterionic form of aspartic acid molecules is reduced, suggesting a possible mechanism through which protein aggregation is prevented. PMID:27327567

  2. 2-(hydroxymethyl)aspartic acid: synthesis, crystal structure, and reaction with a transaminase

    Energy Technology Data Exchange (ETDEWEB)

    Walsh, J.J.; Metzler, D.E.; Powell, D.; Jacobson, R.A.

    1980-11-05

    The synthesis and x-ray crystal structure of 2-(hydroxymethyl) aspartic acid and the preliminary evaluation of its interaction with cytosolic aspartate aminotransferase of pig heart are described. A dissociation constant 1.4 mM for the L-2-(hydroxymethyl) aspartate complex with the enzyme was obtained. 2 figures. (DP)

  3. Preparation and enantiosorption of L-aspartic acid pillared hydrotalcites

    Institute of Scientific and Technical Information of China (English)

    PENG Xia-hui; HUANG Ke-long

    2007-01-01

    L-aspartic acid (Asp) pillared hydrotalcites were prepared by direct reaction of the L-Asp anion with layered double hydroxides (LDHs). The obtained samples were characterized by X-ray diffractometry (XRD), Fourier transform infrared (FTIR),and thermogravimetric and differential thermal analysis (TG/DTA). The results show that the initial interlayer carbonate ions can be completely replaced by the L-Asp anion under the controlled conditions. The pillared hydrotalcites have a crystallized supramolecular structure and thermal stability. The L-Asp pillared LDHs were used in the enantiosorption of enantiopure phenylalanine (Phe), the results suggest that L-Asp pillared LDHs exhibit an excellent enantiosorption capability for D-Phe, and the adsorption isotherm fits Freundlich equation.

  4. Biocatalytic Enantioselective Synthesis of N-Substituted Aspartic Acids by Aspartate Ammonia Lyase

    NARCIS (Netherlands)

    Weiner, Barbara; Poelarends, Gerrit J.; Janssen, Dick B.; Feringa, Ben L.

    2008-01-01

    The gene encoding aspartate ammonia lyase (aspB) from Bacillus sp. YM55-1 has been cloned and overexpressed, and the recombinant enzyme containing a C-terminal His6 tag has been purified to homogeneity and subjected to kinetic characterization. Kinetic studies have shown that the His6 tag does not a

  5. Synthesis of 6-phosphofructose aspartic acid and some related Amadori compounds.

    Science.gov (United States)

    Hansen, Alexandar L; Behrman, Edward J

    2016-08-01

    We describe the synthesis and characterization of 6-phosphofructose-aspartic acid, an intermediate in the metabolism of fructose-asparagine by Salmonella. We also report improved syntheses of fructose-asparagine itself and of fructose-aspartic acid. PMID:27258673

  6. Structural and Functional Importance of Transmembrane Domain 3 (TM3) in the Aspartate:Alanine Antiporter AspT: Topology and Function of the Residues of TM3 and Oligomerization of AspT▿

    OpenAIRE

    Nanatani, Kei; Maloney, Peter C.; Abe, Keietsu

    2009-01-01

    AspT, the aspartate:alanine antiporter of Tetragenococcus halophilus, a membrane protein of 543 amino acids with 10 putative transmembrane (TM) helices, is the prototype of the aspartate:alanine exchanger (AAE) family of transporters. Because TM3 (isoleucine 64 to methionine 85) has many amino acid residues that are conserved among members of the AAE family and because TM3 contains two charged residues and four polar residues, it is thought to be located near (or to form part of) the substrat...

  7. The effect of postirradiation application of aspartic acid salts on hemopoietic recovery in sublethally X-irradiated mice

    International Nuclear Information System (INIS)

    The effect of aspartic acid salts, especially of K and Mg aspartates, on certain hematological changes in the peripheral blood and hemopoietic organs of sublethally X-irratiated male mice of the strain C57Bl/10 was investigated. Salts of aspartic acid were administered in tap water after irradiation. A favorable effect of aspartic acid salts on erythropoietic recovery and on regeneration of thymus weight was found during the first two weeks after irradiation. (orig.)

  8. Chiral Asymmetric Structures in Aspartic Acid and Valine Crystals Assessed by Atomic Force Microscopy.

    Science.gov (United States)

    Teschke, Omar; Soares, David Mendez

    2016-03-29

    Structures of crystallized deposits formed by the molecular self-assembly of aspartic acid and valine on silicon substrates were imaged by atomic force microscopy. Images of d- and l-aspartic acid crystal surfaces showing extended molecularly flat sheets or regions separated by single molecule thick steps are presented. Distinct orientation surfaces were imaged, which, combined with the single molecule step size, defines the geometry of the crystal. However, single molecule step growth also reveals the crystal chirality, i.e., growth orientations. The imaged ordered lattice of aspartic acid (asp) and valine (val) mostly revealed periodicities corresponding to bulk terminations, but a previously unreported molecular hexagonal lattice configuration was observed for both l-asp and l-val but not for d-asp or d-val. Atomic force microscopy can then be used to identify the different chiral forms of aspartic acid and valine crystals.

  9. The catalytic role of aspartic acid-92 in a human dual-specific protein-tyrosine-phosphatase.

    Science.gov (United States)

    Denu, J M; Zhou, G; Guo, Y; Dixon, J E

    1995-03-14

    The mechanism of catalysis for the human dual-specific (vaccinia H1-related) protein-tyrosine-phosphatase was investigated. The pH dependence of the kcat value is bell-shaped when p-nitrophenyl phosphate was employed as a model substrate. The kcat/Km pH profile rises with a slope of 2 and decreases with a slope of -1, indicating that two groups must be unprotonated and one group must be protonated for activity. An amino acid residue with an apparent pKa value of 5.5 +/- 0.2 must be unprotonated and a residue with a pKa value of 5.7 must be unprotonated for activity. The pKa value of the catalytic cysteine-124 (C124) was 5.6 +/- 0.1. The aspartic acid-92-asparagine (D92N) mutant enzyme was 100-fold less active than the native enzyme and exhibited the loss of the basic limb in the pH profiles, suggesting that in the native enzyme D92 must be protonated for activity. The D92 residue is conserved throughout the entire family of dual-specific phosphatases. Mutants glutamic acid-6-glutamine, glutamic acid-32-glutamine, aspartic acid-14-asparagine, and aspartic acid-110-asparagine had less than a 2-fold effect on the kinetic parameters when compared to native enzyme. Based upon the lack of a "burst" in rapid reaction kinetics, formation of the intermediate is rate-limiting with both native and D92N mutant enzymes. In agreement with rate-limiting formation of the intermediate, the pKa value of 5.5 for the group which must be unprotonated for activity was assigned to C124.(ABSTRACT TRUNCATED AT 250 WORDS)

  10. L-(4-/sup 11/C)aspartic acid: enzymatic synthesis, myocardial uptake, and metabolism

    Energy Technology Data Exchange (ETDEWEB)

    Barrio, J.R.; Egbert, J.E.; Henze, E.; Schelbert, H.R.; Baumgartner, F.J.

    1982-01-01

    Sterile, pyrogen-free L-(4-/sup 11/C)aspartic acid was prepared from /sup 11/CO/sub 2/ using phosphoenolpyruvate carboxylase and glutamic/oxaloacetic acid transaminase immobilized on Sepharose supports to determine if it is a useful indicator for in vivo, noninvasive determination of myocardial metabolism. An intracoronary bolus injection of L-(4-/sup 11/C)aspartic acid into dog myocardium showed a triexponential clearance curve with maximal production of /sup 11/CO/sub 2/ 100 s after injection. Inactivation of myocardial transaminase activity modified the tracer clearance and inhibited the production of /sup 11/CO/sub 2/. Positron-computed tomography imaging showed that the /sup 11/C activities retained in rhesus monkey myocardium are higher than those observed in dog heart after intravenous injection of L-(4-/sup 11/C)aspartic acid. These findings demonstrated the rapid incorporation of the carbon skeleton of L-aspartic acid into the tricarboxylic acid cycle after enzymatic transamination in myocardium and suggested that L-(4-/sup 11/C)aspartic acid could be of value for in vivo, noninvasive assessment of local myocardial metabolism.

  11. Preparation and properties of poly(aspartic acid)-based hydrogel

    Energy Technology Data Exchange (ETDEWEB)

    Park, H.D. [Korea Institute of Science and Technology, Seoul (Korea, Republic of); Kim, J.H. [SungKyunKwan University, Suwon (Korea, Republic of); Kim, S.H.; Kim, Y.H. [Korea Institute of Science and Technology, Seoul (Korea, Republic of)

    1999-03-01

    High molecular weight polysuccinimide (PSI), as a precursor of poly (aspartic acid), was prepared by thermal polycondensation of L-aspartic acid. The molecular weight was high when phosphoric acid was used as a catalyst, and the ratio to monomer was 0.75 : 1(phosphoric acid : L-aspartic acid). Attempted solution polymerization in various sulfolane/mesitylene mixtures gave only low molecular weight polymers. By the post polymerization of PSI using DCC as a condensing reagent, the molecular weight of PSI could be increased to some extent. Hydrogels was prepared by crosslinking reaction of PSI with diamine, followed by hydrolysis with NaOH either in water or in DMF solution. As high as 104 g water/g-polymer absorption could be obtained from the hydrogel prepared with 3 mol % of hexamethylenediamine. 13 refs., 7 figs., 1 tab.

  12. Studies of the radioprotective properties of nicotinyl compounds, aspartic acid, glutamic acid and methionine

    International Nuclear Information System (INIS)

    Radioprotective properties of sodium salts of nicotinyl aspartic acid, nicotinyl methionyl aspartic acid and nicotinyl glutamic acid were tested in mice (NMRI). Experimental animals were irradiated by rayage (9,5 Gy). Parameters were: survival rate, peritoneal fluid cell count, weight and DNA concentration of spleen, hepatic DNA polymerase activity and rate of protein synthesis, lactate dehydrogenase activity in serum, maltase, sucrase and leucine aminopeptidase activitiy in duodenum and jejunum. Following results were obtained: 1. There was no significant difference in survival rate of treated and untreated animals. In treated animals only a short prolongation of survival time was observed. 2. After irradiation a quick reduction of splenic weight and DNA concentration was measured. 3. A reduction of DNA polymerase activity in liver was observed in treated and untreated mice. The rate of hepatic protein synthesis was similar in all animals. A final decrease was observed. 4. Variable activities of maltase, sucrase and leucine aminopeptidase activity in duodenum and jejunum indicated no radioprotective effect of tested substances. In conclusion of these results the tested substances show no significant radioprotective properties. (orig.)

  13. Aspartic acid in the hippocampus:a biomarker for postoperative cognitive dysfunction

    Institute of Scientific and Technical Information of China (English)

    Rong Hu; Dong Huang; Jianbin Tong; Qin Liao; Zhonghua Hu; Wen Ouyang

    2014-01-01

    This study established an aged rat model of cognitive dysfunction using anesthesia with 2%iso-lfurane and 80%oxygen for 2 hours. Twenty-four hours later, Y-maze test results showed that isoflurane significantly impaired cognitive function in aged rats. Gas chromatography-mass spectrometry results showed that isolfurane also signiifcantly increased the levels of N,N-diethy-lacetamide, n-ethylacetamide, aspartic acid, malic acid and arabinonic acid in the hippocampus of isolfurane-treated rats. Moreover, aspartic acid, N,N-diethylacetamide, n-ethylacetamide and malic acid concentration was positively correlated with the degree of cognitive dysfunction in the isolfurane-treated rats. It is evident that hippocampal metabolite changes are involved in the formation of cognitive dysfunction after isoflurane anesthesia. To further verify these results, this study cultured hippocampal neurons in vitro, which were then treated with aspartic acid (100 µmol/L). Results suggested that aspartic acid concentration in the hippocampus may be a biomarker for predicting the occurrence and disease progress of cognitive dysfunction.

  14. Synthesis of a stable gold hydrosol by the reduction of chloroaurate ions by the amino acid, aspartic acid

    Indian Academy of Sciences (India)

    Saikat Mandal; P R Selvakannan; Sumant Phadtare; Renu Pasricha; Murali Sastry

    2002-10-01

    Development of reliable protocols for the synthesis of nanoparticles of well-defined sizes and good monodispersity is an important aspect of nanotechnology. In this paper, we present details of the synthesis of gold nanoparticles of good monodispersity by the reduction of aqueous chloroaurate ions by the amino acid, aspartic acid. The colloidal gold solution thus formed is extremely stable in time, indicating electrostatic stabilization via nanoparticle surface-bound amino acid molecules. This observation has been used to modulate the size of the gold nanoparticles in solution by varying the molar ratio of chloroaurate ions to aspartic acid in the reaction medium. Characterization of the aspartic acid-reduced gold nanoparticles was carried out by UV-visible spectroscopy, thermogravimetric analysis and transmission electron microscopy. The use of amino acids in the synthesis and stabilization of gold nanoparticle in water has important implications in the development of new protocols for generation of bioconjugate materials.

  15. Does aspartic acid racemization constrain the depth limit of the subsurface biosphere?

    Energy Technology Data Exchange (ETDEWEB)

    Onstott, T. C. [Princeton University; Aubrey, A.D. [Jet Propulsion Laboratory, Pasadena, CA; Kieft, T L [New Mexico Institute of Mining and Technology; Silver, B J [Jet Propulsion Laboratory, Pasadena, CA; Phelps, Tommy Joe [ORNL; Van Heerden, E. [University of the Free State; Opperman, D. J. [University of the Free State; Bada, J L. [Geosciences Research Division, Scripps Instition of Oceanography, Univesity of California San Diego,

    2014-01-01

    Previous studies of the subsurface biosphere have deduced average cellular doubling times of hundreds to thousands of years based upon geochemical models. We have directly constrained the in situ average cellular protein turnover or doubling times for metabolically active micro-organisms based on cellular amino acid abundances, D/L values of cellular aspartic acid, and the in vivo aspartic acid racemization rate. Application of this method to planktonic microbial communities collected from deep fractures in South Africa yielded maximum cellular amino acid turnover times of ~89 years for 1 km depth and 27 C and 1 2 years for 3 km depth and 54 C. The latter turnover times are much shorter than previously estimated cellular turnover times based upon geochemical arguments. The aspartic acid racemization rate at higher temperatures yields cellular protein doubling times that are consistent with the survival times of hyperthermophilic strains and predicts that at temperatures of 85 C, cells must replace proteins every couple of days to maintain enzymatic activity. Such a high maintenance requirement may be the principal limit on the abundance of living micro-organisms in the deep, hot subsurface biosphere, as well as a potential limit on their activity. The measurement of the D/L of aspartic acid in biological samples is a potentially powerful tool for deep, fractured continental and oceanic crustal settings where geochemical models of carbon turnover times are poorly constrained. Experimental observations on the racemization rates of aspartic acid in living thermophiles and hyperthermophiles could test this hypothesis. The development of corrections for cell wall peptides and spores will be required, however, to improve the accuracy of these estimates for environmental samples.

  16. Does aspartic acid racemization constrain the depth limit of the subsurface biosphere?

    Science.gov (United States)

    Onstott, T C; Magnabosco, C; Aubrey, A D; Burton, A S; Dworkin, J P; Elsila, J E; Grunsfeld, S; Cao, B H; Hein, J E; Glavin, D P; Kieft, T L; Silver, B J; Phelps, T J; van Heerden, E; Opperman, D J; Bada, J L

    2014-01-01

    Previous studies of the subsurface biosphere have deduced average cellular doubling times of hundreds to thousands of years based upon geochemical models. We have directly constrained the in situ average cellular protein turnover or doubling times for metabolically active micro-organisms based on cellular amino acid abundances, D/L values of cellular aspartic acid, and the in vivo aspartic acid racemization rate. Application of this method to planktonic microbial communities collected from deep fractures in South Africa yielded maximum cellular amino acid turnover times of ~89 years for 1 km depth and 27 °C and 1-2 years for 3 km depth and 54 °C. The latter turnover times are much shorter than previously estimated cellular turnover times based upon geochemical arguments. The aspartic acid racemization rate at higher temperatures yields cellular protein doubling times that are consistent with the survival times of hyperthermophilic strains and predicts that at temperatures of 85 °C, cells must replace proteins every couple of days to maintain enzymatic activity. Such a high maintenance requirement may be the principal limit on the abundance of living micro-organisms in the deep, hot subsurface biosphere, as well as a potential limit on their activity. The measurement of the D/L of aspartic acid in biological samples is a potentially powerful tool for deep, fractured continental and oceanic crustal settings where geochemical models of carbon turnover times are poorly constrained. Experimental observations on the racemization rates of aspartic acid in living thermophiles and hyperthermophiles could test this hypothesis. The development of corrections for cell wall peptides and spores will be required, however, to improve the accuracy of these estimates for environmental samples. PMID:24289240

  17. Does aspartic acid racemization constrain the depth limit of the subsurface biosphere?

    Science.gov (United States)

    Onstott, T C; Magnabosco, C; Aubrey, A D; Burton, A S; Dworkin, J P; Elsila, J E; Grunsfeld, S; Cao, B H; Hein, J E; Glavin, D P; Kieft, T L; Silver, B J; Phelps, T J; van Heerden, E; Opperman, D J; Bada, J L

    2014-01-01

    Previous studies of the subsurface biosphere have deduced average cellular doubling times of hundreds to thousands of years based upon geochemical models. We have directly constrained the in situ average cellular protein turnover or doubling times for metabolically active micro-organisms based on cellular amino acid abundances, D/L values of cellular aspartic acid, and the in vivo aspartic acid racemization rate. Application of this method to planktonic microbial communities collected from deep fractures in South Africa yielded maximum cellular amino acid turnover times of ~89 years for 1 km depth and 27 °C and 1-2 years for 3 km depth and 54 °C. The latter turnover times are much shorter than previously estimated cellular turnover times based upon geochemical arguments. The aspartic acid racemization rate at higher temperatures yields cellular protein doubling times that are consistent with the survival times of hyperthermophilic strains and predicts that at temperatures of 85 °C, cells must replace proteins every couple of days to maintain enzymatic activity. Such a high maintenance requirement may be the principal limit on the abundance of living micro-organisms in the deep, hot subsurface biosphere, as well as a potential limit on their activity. The measurement of the D/L of aspartic acid in biological samples is a potentially powerful tool for deep, fractured continental and oceanic crustal settings where geochemical models of carbon turnover times are poorly constrained. Experimental observations on the racemization rates of aspartic acid in living thermophiles and hyperthermophiles could test this hypothesis. The development of corrections for cell wall peptides and spores will be required, however, to improve the accuracy of these estimates for environmental samples.

  18. Does Aspartic Acid Racemization Constrain the Depth Limit of the Subsurface Biosphere?

    Science.gov (United States)

    Onstott, T C.; Magnabosco, C.; Aubrey, A. D.; Burton, A. S.; Dworkin, J. P.; Elsila, J. E.; Grunsfeld, S.; Cao, B. H.; Hein, J. E.; Glavin, D. P.; Kieft, T. L.; Silver, B. J.; Phelps, T. J.; Heerden, E. Van; Opperman, D. J.; Bada, J. L.

    2013-01-01

    Previous studies of the subsurface biosphere have deduced average cellular doubling times of hundreds to thousands of years based upon geochemical models. We have directly constrained the in situ average cellular protein turnover or doubling times for metabolically active micro-organisms based on cellular amino acid abundances, D/L values of cellular aspartic acid, and the in vivo aspartic acid racemization rate. Application of this method to planktonic microbial communities collected from deep fractures in South Africa yielded maximum cellular amino acid turnover times of approximately 89 years for 1 km depth and 27 C and 1-2 years for 3 km depth and 54 C. The latter turnover times are much shorter than previously estimated cellular turnover times based upon geochemical arguments. The aspartic acid racemization rate at higher temperatures yields cellular protein doubling times that are consistent with the survival times of hyperthermophilic strains and predicts that at temperatures of 85 C, cells must replace proteins every couple of days to maintain enzymatic activity. Such a high maintenance requirement may be the principal limit on the abundance of living micro-organisms in the deep, hot subsurface biosphere, as well as a potential limit on their activity. The measurement of the D/L of aspartic acid in biological samples is a potentially powerful tool for deep, fractured continental and oceanic crustal settings where geochemical models of carbon turnover times are poorly constrained. Experimental observations on the racemization rates of aspartic acid in living thermophiles and hyperthermophiles could test this hypothesis. The development of corrections for cell wall peptides and spores will be required, however, to improve the accuracy of these estimates for environmental samples.

  19. Predicting three-dimensional conformations of peptides constructed of only glycine, alanine, aspartic acid, and valine.

    Science.gov (United States)

    Oda, Akifumi; Fukuyoshi, Shuichi

    2015-06-01

    The GADV hypothesis is a form of the protein world hypothesis, which suggests that life originated from proteins (Lacey et al. 1999; Ikehara 2002; Andras 2006). In the GADV hypothesis, life is thought to have originated from primitive proteins constructed of only glycine, alanine, aspartic acid, and valine ([GADV]-proteins). In this study, the three-dimensional (3D) conformations of randomly generated short [GADV]-peptides were computationally investigated using replica-exchange molecular dynamics (REMD) simulations (Sugita and Okamoto 1999). Because the peptides used in this study consisted of only 20 residues each, they could not form certain 3D structures. However, the conformational tendencies of the peptides were elucidated by analyzing the conformational ensembles generated by REMD simulations. The results indicate that secondary structures can be formed in several randomly generated [GADV]-peptides. A long helical structure was found in one of the hydrophobic peptides, supporting the conjecture of the GADV hypothesis that many peptides aggregated to form peptide multimers with enzymatic activity in the primordial soup. In addition, these results indicate that REMD simulations can be used for the structural investigation of short peptides.

  20. Predicting Three-Dimensional Conformations of Peptides Constructed of Only Glycine, Alanine, Aspartic Acid, and Valine

    Science.gov (United States)

    Oda, Akifumi; Fukuyoshi, Shuichi

    2015-06-01

    The GADV hypothesis is a form of the protein world hypothesis, which suggests that life originated from proteins (Lacey et al. 1999; Ikehara 2002; Andras 2006). In the GADV hypothesis, life is thought to have originated from primitive proteins constructed of only glycine, alanine, aspartic acid, and valine ([GADV]-proteins). In this study, the three-dimensional (3D) conformations of randomly generated short [GADV]-peptides were computationally investigated using replica-exchange molecular dynamics (REMD) simulations (Sugita and Okamoto 1999). Because the peptides used in this study consisted of only 20 residues each, they could not form certain 3D structures. However, the conformational tendencies of the peptides were elucidated by analyzing the conformational ensembles generated by REMD simulations. The results indicate that secondary structures can be formed in several randomly generated [GADV]-peptides. A long helical structure was found in one of the hydrophobic peptides, supporting the conjecture of the GADV hypothesis that many peptides aggregated to form peptide multimers with enzymatic activity in the primordial soup. In addition, these results indicate that REMD simulations can be used for the structural investigation of short peptides.

  1. Accumulation of aspartic acid421- and glutamic acid391-cleaved tau in neurofibrillary tangles correlates with progression in Alzheimer disease.

    Science.gov (United States)

    Basurto-Islas, Gustavo; Luna-Muñoz, Jose; Guillozet-Bongaarts, Angela L; Binder, Lester I; Mena, Raul; García-Sierra, Francisco

    2008-05-01

    Truncations of tau protein at aspartic acid421 (D421) and glutamic acid391 (E391) residues are associated with neurofibrillary tangles (NFTs) in the brains of Alzheimer disease (AD) patients. Using immunohistochemistry with antibodies to D421- and E391-truncated tau (Tau-C3 and MN423, respectively), we correlated the presence of NFTs composed of these truncated tau proteins with clinical and neuropathologic parameters in 17 AD and 23 non-AD control brains. The densities of NFTs composed of D421- or E391-truncated tau correlated with clinical dementia index and Braak staging in AD. Glutamic acid391 tau truncation was prominent in the entorhinal cortex, whereas D421 truncation was prominent in the subiculum, suggesting that NFTs composed of either D421- or E391-truncated tau may be formed mutually exclusively in these areas. Both truncations were associated with the prevalence of the apolipoprotein E epsilon4 allele. By double labeling, intact tau in NFTs was commonly associated with D421-cleaved tau but not with E391-truncated tau; D421-cleaved tau was never associated with E391-truncated tau. These results indicate that tau is not randomly proteolyzed at different domains, and that proteolysis occurs sequentially from the C-terminus to inner regions of tau in AD progression. Identification of NFTs composed of tau at different stages of truncation may facilitate assessment of neurofibrillary pathology in AD.

  2. Strains of Lactococcus lactis with a partial pyrimidine requirement show sensitivity toward aspartic acid

    DEFF Research Database (Denmark)

    Wadskov-Hansen, Steen Lyders Lerche; Martinussen, Jan

    2009-01-01

    that the partial pyrimidine requirement can be explained by a low specific activity of the pyrimidine biosynthetic enzymes. In conclusion, L. lactis LM0230 during the process of plasmid- and prophage-curing has acquired a partial pyrimidine requirement resulting in sensitivity toward aspartic acid....

  3. Searsia species with affinity to the N-methyl-d-aspartic acid (NMDA) receptor

    DEFF Research Database (Denmark)

    Jäger, Anna; Knap, D.M.; Nielsen, Birgitte;

    2012-01-01

    Species of Searsia are used in traditional medicine to treat epilepsy. Previous studies on S. dentata and S. pyroides have shown that this is likely mediated via the N-methyl-d-aspartic acid (NMDA) receptor. Ethanolic extracts of leaves of six Searsia species were tested in a binding assay for...... accessible Searsia species can be used in traditional medicine....

  4. N-Hydroxypyrazolyl glycine derivatives as selective N-methyl-D-aspartic acid receptor ligands

    DEFF Research Database (Denmark)

    Clausen, Rasmus Prætorius; Christensen, Caspar; Hansen, Kasper Bø;

    2008-01-01

    glycine (NHP5G) derivatives are selectively recognized by N-methyl- d-aspartic acid (NMDA) receptors and that the ( R)-enantiomers are preferred. Moreover, several of the compounds are able to discriminate between individual subtypes among the NMDA receptors, providing new pharmacological tools. For......A series of analogues based on N-hydroxypyrazole as a bioisostere for the distal carboxylate group of aspartate have been designed, synthesized, and pharmacologically characterized. Affinity studies on the major glutamate receptor subgroups show that these 4-substituted N-hydroxypyrazol-5-yl...

  5. N-(Fluoren-9-ylmethoxycarbonyl-l-aspartic acid 4-tert-butyl ester

    Directory of Open Access Journals (Sweden)

    Kazuhiko Yamada

    2009-11-01

    Full Text Available The bond distances and bond angles of the title compound, C23H25NO6, are consistent with values typically found for fluoren-9-ylmethoxycarbonyl-protected amino acids. The conformations of the backbone and the side chain are slightly different from those of l-aspartic acid. The crystal structure exhibits two intermolecular hydrogen bonds, forming a two-dimensional sheet structure parallel to the ab plane.

  6. Age estimation in forensic sciences: Application of combined aspartic acid racemization and radiocarbon analysis

    Energy Technology Data Exchange (ETDEWEB)

    Alkass, K; Buchholz, B A; Ohtani, S; Yamamoto, T; Druid, H; Spalding, S L

    2009-11-02

    Age determination of unknown human bodies is important in the setting of a crime investigation or a mass disaster, since the age at death, birth date and year of death, as well as gender, can guide investigators to the correct identity among a large number of possible matches. Traditional morphological methods used by anthropologists to determine age are often imprecise, whereas chemical analysis of tooth dentin, such as aspartic acid racemization has shown reproducible and more precise results. In this paper we analyze teeth from Swedish individuals using both aspartic acid racemization and radiocarbon methodologies. The rationale behind using radiocarbon analysis is that above-ground testing of nuclear weapons during the cold war (1955-1963) caused an extreme increase in global levels of carbon-14 ({sup 14}C) which have been carefully recorded over time. Forty-four teeth from 41 individuals were analyzed using aspartic acid racemization analysis of tooth crown dentin or radiocarbon analysis of enamel and ten of these were split and subjected to both radiocarbon and racemization analysis. Combined analysis showed that the two methods correlated well (R2=0.66, p < 0.05). Radiocarbon analysis showed an excellent precision with an overall absolute error of 0.6 {+-} 04 years. Aspartic acid racemization also showed a good precision with an overall absolute error of 5.4 {+-} 4.2 years. Whereas radiocarbon analysis gives an estimated year of birth, racemization analysis indicates the chronological age of the individual at the time of death. We show how these methods in combination can also assist in the estimation of date of death of an unidentified victim. This strategy can be of significant assistance in forensic casework involving dead victim identification.

  7. Absorption and utilization of organic matter by the strict autotroph, Thiobacillus thiooxidans, with special reference to aspartic acid.

    Science.gov (United States)

    Butler, R G; Umbreit, W W

    1966-02-01

    Butler, Richard G. (Rutgers, The State University, New Brunswick, N.J.), and Wayne W. Umbreit. Absorption and utilization of organic matter by the strict autotroph, Thiobacillus thiooxidans, with special reference to aspartic acid. J. Bacteriol. 91:661-666. 1966.-The strictly autotrophic bacterium, Thiobacillus thiooxidans, can be shown to assimilate a variety of organic materials. Aspartic acid can be assimilated into protein and can be converted into CO(2), but even in the presence of sulfur it cannot serve as the sole source of carbon for growth. The reason appears to be that aspartic acid is converted into inhibitory materials.

  8. D-Aspartic acid: an endogenous amino acid with an important neuroendocrine role.

    Science.gov (United States)

    D'Aniello, Antimo

    2007-02-01

    D-Aspartic acid (d-Asp), an endogenous amino acid present in vertebrates and invertebrates, plays an important role in the neuroendocrine system, as well as in the development of the nervous system. During the embryonic stage of birds and the early postnatal life of mammals, a transient high concentration of d-Asp takes place in the brain and in the retina. d-Asp also acts as a neurotransmitter/neuromodulator. Indeed, this amino acid has been detected in synaptosomes and in synaptic vesicles, where it is released after chemical (K(+) ion, ionomycin) or electric stimuli. Furthermore, d-Asp increases cAMP in neuronal cells and is transported from the synaptic clefts to presynaptic nerve cells through a specific transporter. In the endocrine system, instead, d-Asp is involved in the regulation of hormone synthesis and release. For example, in the rat hypothalamus, it enhances gonadotropin-releasing hormone (GnRH) release and induces oxytocin and vasopressin mRNA synthesis. In the pituitary gland, it stimulates the secretion of the following hormones: prolactin (PRL), luteinizing hormone (LH), and growth hormone (GH) In the testes, it is present in Leydig cells and is involved in testosterone and progesterone release. Thus, a hypothalamus-pituitary-gonads pathway, in which d-Asp is involved, has been formulated. In conclusion, the present work is a summary of previous and current research done on the role of d-Asp in the nervous and endocrine systems of invertebrates and vertebrates, including mammals. PMID:17118457

  9. N-Methyl-D-aspartic Acid (NMDA in the nervous system of the amphioxus Branchiostoma lanceolatum

    Directory of Open Access Journals (Sweden)

    Garcia-Fernàndez Jordi

    2007-12-01

    Full Text Available Abstract Background NMDA (N-methyl-D-aspartic acid is a widely known agonist for a class of glutamate receptors, the NMDA type. Synthetic NMDA elicits very strong activity for the induction of hypothalamic factors and hypophyseal hormones in mammals. Moreover, endogenous NMDA has been found in rat, where it has a role in the induction of GnRH (Gonadotropin Releasing Hormone in the hypothalamus, and of LH (Luteinizing Hormone and PRL (Prolactin in the pituitary gland. Results In this study we show evidence for the occurrence of endogenous NMDA in the amphioxus Branchiostoma lanceolatum. A relatively high concentration of NMDA occurs in the nervous system of this species (3.08 ± 0.37 nmol/g tissue in the nerve cord and 10.52 ± 1.41 nmol/g tissue in the cephalic vesicle. As in rat, in amphioxus NMDA is also biosynthesized from D-aspartic acid (D-Asp by a NMDA synthase (also called D-aspartate methyl transferase. Conclusion Given the simplicity of the amphioxus nervous and endocrine systems compared to mammalian, the discovery of NMDA in this protochordate is important to gain insights into the role of endogenous NMDA in the nervous and endocrine systems of metazoans and particularly in the chordate lineage.

  10. Inclusion Behavior of Dimer b-Cyclodextrin Bridged with Aspartic Acid Derivative

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The b-cyclodextrin (CD) dimer bridged with aspartic acid (ASP) derivative, FITC-ASP(NH-b-CD)2 (Host, FITC=fluorescein-4-isothiocyanate), was synthesized. Fluorescence polarization study showed that the novel host formed an inclusion compound, [FITC-ASP(NH-b-CD)2]ATA, for which Kd was determined to be 5.0×10-6 mol/L by Beacon 2000 Analyzer, when ATA (Guest) = Adm-Trp-Arg-Arg-NH2 (Adm = 1-adamantanecarboxylic acid, Trp = tryptophan, Arg = arginine), where Kd is the dissociation constant in aqueous solution at 298 K.

  11. Solvent-Free Polymerization of L-Aspartic Acid in the Presence of D-Sorbitol to Obtain Water Soluble or Network Copolymers

    Science.gov (United States)

    L-aspartic acid was thermally polymerized in the presence of D-sorbitol with the goal of synthesizing new, higher molecular weight water soluble and absorbent copolymers. No reaction occurred when aspartic acid alone was heated at 170 or 200 degrees C. In contrast, heating sorbitol and aspartic ac...

  12. Structural and functional importance of transmembrane domain 3 (TM3) in the aspartate:alanine antiporter AspT: topology and function of the residues of TM3 and oligomerization of AspT.

    Science.gov (United States)

    Nanatani, Kei; Maloney, Peter C; Abe, Keietsu

    2009-04-01

    AspT, the aspartate:alanine antiporter of Tetragenococcus halophilus, a membrane protein of 543 amino acids with 10 putative transmembrane (TM) helices, is the prototype of the aspartate:alanine exchanger (AAE) family of transporters. Because TM3 (isoleucine 64 to methionine 85) has many amino acid residues that are conserved among members of the AAE family and because TM3 contains two charged residues and four polar residues, it is thought to be located near (or to form part of) the substrate translocation pathway that includes the binding site for the substrates. To elucidate the role of TM3 in the transport process, we carried out cysteine-scanning mutagenesis. The substitutions of tyrosine 75 and serine 84 had the strongest inhibitory effects on transport (initial rates of l-aspartate transport were below 15% of the rate for cysteine-less AspT). Considerable but less-marked effects were observed upon the replacement of methionine 70, phenylalanine 71, glycine 74, arginine 76, serine 83, and methionine 85 (initial rates between 15% and 30% of the rate for cysteine-less AspT). Introduced cysteine residues at the cytoplasmic half of TM3 could be labeled with Oregon green maleimide (OGM), whereas cysteines close to the periplasmic half (residues 64 to 75) were not labeled. These results suggest that TM3 has a hydrophobic core on the periplasmic half and that hydrophilic residues on the cytoplasmic half of TM3 participate in the formation of an aqueous cavity in membranes. Furthermore, the presence of l-aspartate protected the cysteine introduced at glycine 62 against a reaction with OGM. In contrast, l-aspartate stimulated the reactivity of the cysteine introduced at proline 79 with OGM. These results demonstrate that TM3 undergoes l-aspartate-induced conformational alterations. In addition, nonreducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis analyses and a glutaraldehyde cross-linking assay suggest that functional AspT forms homo-oligomers as a

  13. Structural and Functional Importance of Transmembrane Domain 3 (TM3) in the Aspartate:Alanine Antiporter AspT: Topology and Function of the Residues of TM3 and Oligomerization of AspT▿

    Science.gov (United States)

    Nanatani, Kei; Maloney, Peter C.; Abe, Keietsu

    2009-01-01

    AspT, the aspartate:alanine antiporter of Tetragenococcus halophilus, a membrane protein of 543 amino acids with 10 putative transmembrane (TM) helices, is the prototype of the aspartate:alanine exchanger (AAE) family of transporters. Because TM3 (isoleucine 64 to methionine 85) has many amino acid residues that are conserved among members of the AAE family and because TM3 contains two charged residues and four polar residues, it is thought to be located near (or to form part of) the substrate translocation pathway that includes the binding site for the substrates. To elucidate the role of TM3 in the transport process, we carried out cysteine-scanning mutagenesis. The substitutions of tyrosine 75 and serine 84 had the strongest inhibitory effects on transport (initial rates of l-aspartate transport were below 15% of the rate for cysteine-less AspT). Considerable but less-marked effects were observed upon the replacement of methionine 70, phenylalanine 71, glycine 74, arginine 76, serine 83, and methionine 85 (initial rates between 15% and 30% of the rate for cysteine-less AspT). Introduced cysteine residues at the cytoplasmic half of TM3 could be labeled with Oregon green maleimide (OGM), whereas cysteines close to the periplasmic half (residues 64 to 75) were not labeled. These results suggest that TM3 has a hydrophobic core on the periplasmic half and that hydrophilic residues on the cytoplasmic half of TM3 participate in the formation of an aqueous cavity in membranes. Furthermore, the presence of l-aspartate protected the cysteine introduced at glycine 62 against a reaction with OGM. In contrast, l-aspartate stimulated the reactivity of the cysteine introduced at proline 79 with OGM. These results demonstrate that TM3 undergoes l-aspartate-induced conformational alterations. In addition, nonreducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis analyses and a glutaraldehyde cross-linking assay suggest that functional AspT forms homo-oligomers as a

  14. Structural and functional importance of transmembrane domain 3 (TM3) in the aspartate:alanine antiporter AspT: topology and function of the residues of TM3 and oligomerization of AspT.

    Science.gov (United States)

    Nanatani, Kei; Maloney, Peter C; Abe, Keietsu

    2009-04-01

    AspT, the aspartate:alanine antiporter of Tetragenococcus halophilus, a membrane protein of 543 amino acids with 10 putative transmembrane (TM) helices, is the prototype of the aspartate:alanine exchanger (AAE) family of transporters. Because TM3 (isoleucine 64 to methionine 85) has many amino acid residues that are conserved among members of the AAE family and because TM3 contains two charged residues and four polar residues, it is thought to be located near (or to form part of) the substrate translocation pathway that includes the binding site for the substrates. To elucidate the role of TM3 in the transport process, we carried out cysteine-scanning mutagenesis. The substitutions of tyrosine 75 and serine 84 had the strongest inhibitory effects on transport (initial rates of l-aspartate transport were below 15% of the rate for cysteine-less AspT). Considerable but less-marked effects were observed upon the replacement of methionine 70, phenylalanine 71, glycine 74, arginine 76, serine 83, and methionine 85 (initial rates between 15% and 30% of the rate for cysteine-less AspT). Introduced cysteine residues at the cytoplasmic half of TM3 could be labeled with Oregon green maleimide (OGM), whereas cysteines close to the periplasmic half (residues 64 to 75) were not labeled. These results suggest that TM3 has a hydrophobic core on the periplasmic half and that hydrophilic residues on the cytoplasmic half of TM3 participate in the formation of an aqueous cavity in membranes. Furthermore, the presence of l-aspartate protected the cysteine introduced at glycine 62 against a reaction with OGM. In contrast, l-aspartate stimulated the reactivity of the cysteine introduced at proline 79 with OGM. These results demonstrate that TM3 undergoes l-aspartate-induced conformational alterations. In addition, nonreducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis analyses and a glutaraldehyde cross-linking assay suggest that functional AspT forms homo-oligomers as a

  15. [Aspartic Acid Generated in the Process of Chlorination Disinfection By-product Dichloroacetonitrile].

    Science.gov (United States)

    Ding, Chun-sheng; Li, Nai-jun; Zhang, Tao; Zhang, Meng-qing

    2016-05-15

    In this study, a method was developed for the determination of dichloroacetonitrile (DCAN) in drinking water by liquid- liquid micro-extraction and gas chromatography/mass spectrometry ( LLE-GC/MS), which used 1,2-dibromopropane as the internal standard and methyl tertiary butyl ether (MTBE) as the extractant for high accuracy. The aspartic acid was used as the precursor of the DCAN formation during chlorination and the influencing factors were evaluated. The formation mechanism of DCAN was also discussed. The results showed that the DCAN amount increased with the increase of pH value under the neutral and acidic conditions, however, the amount of DCAN decreased with the increase of pH value under the alkali condition. And the final amount of DCAN under the alkali condition was much less than that under the neutral and acidic conditions. It was also found that the DCAN amount increased with the increase of chlorine addition, while the temperature in the range of 10-30°C had little influence on the DCAN formation. The formation process of the DCAN from aspartic acid by chlorination included seven steps, such as substitution, decarboxylation, oxidation, etc and ultimately formed DCAN. PMID:27506037

  16. [Aspartic Acid Generated in the Process of Chlorination Disinfection By-product Dichloroacetonitrile].

    Science.gov (United States)

    Ding, Chun-sheng; Li, Nai-jun; Zhang, Tao; Zhang, Meng-qing

    2016-05-15

    In this study, a method was developed for the determination of dichloroacetonitrile (DCAN) in drinking water by liquid- liquid micro-extraction and gas chromatography/mass spectrometry ( LLE-GC/MS), which used 1,2-dibromopropane as the internal standard and methyl tertiary butyl ether (MTBE) as the extractant for high accuracy. The aspartic acid was used as the precursor of the DCAN formation during chlorination and the influencing factors were evaluated. The formation mechanism of DCAN was also discussed. The results showed that the DCAN amount increased with the increase of pH value under the neutral and acidic conditions, however, the amount of DCAN decreased with the increase of pH value under the alkali condition. And the final amount of DCAN under the alkali condition was much less than that under the neutral and acidic conditions. It was also found that the DCAN amount increased with the increase of chlorine addition, while the temperature in the range of 10-30°C had little influence on the DCAN formation. The formation process of the DCAN from aspartic acid by chlorination included seven steps, such as substitution, decarboxylation, oxidation, etc and ultimately formed DCAN.

  17. Racemization of aspartic acid and phenylalanine in the sweetener aspartame at 100 degrees C.

    OpenAIRE

    Boehm, M F; Bada, J L

    1984-01-01

    The racemization half-lives (i.e., the time required to reach a D/L = 0.33) at pH 6.8 for aspartic acid and phenylalanine in the sweetener aspartame (L-aspartyl-L-phenylalanine methyl ester) were determined to be 13 and 23 hours, respectively, at 100 degrees C. Racemization at this pH does not occur in aspartame but rather in its diketopiperazine decomposition product. Our results indicate that the use of aspartame to sweeten neutral pH foods and beverages that are then heated at elevated tem...

  18. A central role for bifunctional aspartate/prephenate aminotransferase in the biosynthesis of amino acids in plant plastids.

    OpenAIRE

    El-Azaz, Jorge; Cánovas, Francisco M.; de la Torre, Fernando; Ávila, Concepción

    2014-01-01

    A central role for bifunctional aspartate/prephenate aminotransferase in the biosynthesis of amino acids in plant plastids. Fernando de la Torre, Jorge El-Azaz, Concepción Ávila, Francisco M. Cánovas Departamento de Biología Molecular y Bioquímica. Universidad de Málaga. Bifunctional aspartate/prephenate aminotransferases (AAT/PAT) are plastid-located enzymes encoded by a single locus in all reported plants, which develop two different enzymatic activities: aspartate aminotransferas...

  19. Aspartic acid racemization in dentin of the third molar for age estimation of the Chaoshan population in South China.

    Science.gov (United States)

    Chen, Shisheng; Lv, Yanyi; Wang, Dian; Yu, Xiaojun

    2016-09-01

    Aspartic acid racemization in teeth has been increasingly used to estimate chronological age with a considerably high accuracy in forensic practice. The Chaoshan population in South China is relatively isolated in geography, and has specific lifestyle and dietary inhibits. It is still unknown whether this method is suitable for this population. The aim of this study was to analyze the relationship between chronological age and the d/l aspartic acid ratio in dentin in the third molar tooth of the Chaoshan population. Fifty-eight non-carious third molar teeth (31 mandibles and 27 maxillae), from 58 living individuals of known age (24 males and 34 females), were retrieved. Dentin was extracted from these teeth. The d- and l-aspartic acids in dentins were separated and detected by high performance liquid chromatography (HPLC). Linear regression was performed between the d/l aspartic acid ratio of dentins and chronological age. Results showed that the correlation coefficient (r) was 0.969, and the mean absolute error (MAE) was 2.19 years, its standard deviation (SD) was ±1.53 years, indicating excellent correlation. There was no significant difference in racemization rates of dentin between sexes (P=0.113, F=2.6), or between mandibles and maxillae (P=0.964, F=0.000). Results indicate that the ratio of the d and l forms of aspartic acid of dentins, in the third molar, is closely correlated with chronological age, special lifestyle do no obviously affect the accuracy of the age estimations by aspartic acid racemization of the dentin in the third molar and that aspartic acid racemization in the third molar dentin can be used as an accurate method to estimate chronological age in the Chaoshan population in South China.

  20. Nanostructured aluminium oxide powders obtained by aspartic acid-nitrate gel-combustion routes

    Energy Technology Data Exchange (ETDEWEB)

    Gardey Merino, Maria Celeste, E-mail: mcgardey@frm.utn.edu.a [Laboratorio de Investigaciones y Servicios Ambientales Mendoza (LISAMEN) - CCT - CONICET, Avda. Ruiz Leal s/n, Parque Gral. San Martin, (M5502IRA) Ciudad de Mendoza, Prov. de Mendoza (Argentina); Grupo CLIOPE, Universidad Tecnologica Nacional - Facultad Regional Mendoza, Rodriguez 273, (M5502AJE) Ciudad de Mendoza, Prov. de Mendoza (Argentina); Lascalea, Gustavo E. [Laboratorio de Investigaciones y Servicios Ambientales Mendoza (LISAMEN) - CCT - CONICET, Avda. Ruiz Leal s/n, Parque Gral. San Martin, (M5502IRA) Ciudad de Mendoza, Prov. de Mendoza (Argentina); Sanchez, Laura M. [CINSO (Centro de Investigaciones en Solidos), CITEFA - CONICET, J.B. de La Salle 4397, (B1603ALO) Villa Martelli, Prov. de Buenos Aires (Argentina); Vazquez, Patricia G. [Centro de Investigacion y Desarrollo en Ciencias Aplicadas ' Dr. Jorge J. Ronco' (CINDECA), CONICET, Universidad Nacional de La Plata, Calle 47 nro. 257, (B1900AJK) La Plata, Prov. de Buenos Aires (Argentina); Cabanillas, Edgardo D. [CONICET and Centro Atomico Constituyentes, Comision Nacional de Energia Atomica, Gral. Paz 1499, (1650) San Martin, Prov. de Buenos Aires (Argentina); Lamas, Diego G. [CINSO (Centro de Investigaciones en Solidos), CITEFA - CONICET, J.B. de La Salle 4397, (B1603ALO) Villa Martelli, Prov. de Buenos Aires (Argentina)

    2010-04-16

    In this work, two new gel-combustion routes for the synthesis of Al{sub 2}O{sub 3} nanopowders with aspartic acid as fuel are presented. The first route is a conventional stoichiometric process, while the second one is a non-stoichiometric, pH-controlled process. These routes were compared with similar synthesis procedures using glycine as fuel, which are well-known in the literature. The samples were calcined in air at different temperatures, in a range of 600-1200 {sup o}C. They were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and BET specific surface area. Different phases were obtained depending on the calcination temperature: amorphous, {gamma} (metastable) or {alpha} (stable). The amorphous-to-{gamma} transition was found for calcination temperatures in the range of 700-900 {sup o}C, while the {gamma}-to-{alpha} one was observed for calcination temperatures of 1100-1200 {sup o}C. The retention of the metastable {gamma} phase is probably due to a crystallite size effect. It transforms to the {alpha} phase after the crystallite size increases over a critical size during the calcination process at 1200 {sup o}C. The highest BET specific surface areas were obtained for both nitrate-aspartic acid routes proposed in this work, reaching values of about 50 m{sup 2}/g.

  1. Development of Novel Radiogallium-Labeled Bone Imaging Agents Using Oligo-Aspartic Acid Peptides as Carriers

    OpenAIRE

    Kazuma Ogawa; Atsushi Ishizaki; Kenichiro Takai; Yoji Kitamura; Tatsuto Kiwada; Kazuhiro Shiba; Akira Odani

    2013-01-01

    (68)Ga (T 1/2 = 68 min, a generator-produced nuclide) has great potential as a radionuclide for clinical positron emission tomography (PET). Because poly-glutamic and poly-aspartic acids have high affinity for hydroxyapatite, to develop new bone targeting (68)Ga-labeled bone imaging agents for PET, we used 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) as a chelating site and conjugated aspartic acid peptides of varying lengths. Subsequently, we compared Ga complexes, Ga-DOTA...

  2. Synthesis, Characterization, and Antimicrobial Activities of Coordination Compounds of Aspartic Acid

    Directory of Open Access Journals (Sweden)

    T. O. Aiyelabola

    2016-01-01

    Full Text Available Coordination compounds of aspartic acid were synthesized in basic and acidic media, with metal ligand M : L stoichiometric ratio 1 : 2. The complexes were characterized using infrared, electronic and magnetic susceptibility measurements, and mass spectrometry. Antimicrobial activity of the compounds was determined against three Gram-positive and three Gram-negative bacteria and one fungus. The results obtained indicated that the availability of donor atoms used for coordination was a function of the pH of the solution in which the reaction was carried out. This resulted in varying geometrical structures for the complexes. The compounds exhibited a broad spectrum of activity and in some cases better activity than the standard.

  3. Solution structure of the squash aspartic acid proteinase inhibitor (SQAPI) and mutational analysis of pepsin inhibition.

    Science.gov (United States)

    Headey, Stephen J; Macaskill, Ursula K; Wright, Michele A; Claridge, Jolyon K; Edwards, Patrick J B; Farley, Peter C; Christeller, John T; Laing, William A; Pascal, Steven M

    2010-08-27

    The squash aspartic acid proteinase inhibitor (SQAPI), a proteinaceous proteinase inhibitor from squash, is an effective inhibitor of a range of aspartic proteinases. Proteinaceous aspartic proteinase inhibitors are rare in nature. The only other example in plants probably evolved from a precursor serine proteinase inhibitor. Earlier work based on sequence homology modeling suggested SQAPI evolved from an ancestral cystatin. In this work, we determined the solution structure of SQAPI using NMR and show that SQAPI shares the same fold as a plant cystatin. The structure is characterized by a four-strand anti-parallel beta-sheet gripping an alpha-helix in an analogous manner to fingers of a hand gripping a tennis racquet. Truncation and site-specific mutagenesis revealed that the unstructured N terminus and the loop connecting beta-strands 1 and 2 are important for pepsin inhibition, but the loop connecting strands 3 and 4 is not. Using ambiguous restraints based on the mutagenesis results, SQAPI was then docked computationally to pepsin. The resulting model places the N-terminal strand of SQAPI in the S' side of the substrate binding cleft, whereas the first SQAPI loop binds on the S side of the cleft. The backbone of SQAPI does not interact with the pepsin catalytic Asp(32)-Asp(215) diad, thus avoiding cleavage. The data show that SQAPI does share homologous structural elements with cystatin and appears to retain a similar protease inhibitory mechanism despite its different target. This strongly supports our hypothesis that SQAPI evolved from an ancestral cystatin.

  4. A negatively charged transmembrane aspartate residue controls activation of the relaxin-3 receptor RXFP3.

    Science.gov (United States)

    Liu, Yu; Zhang, Lei; Shao, Xiao-Xia; Hu, Meng-Jun; Liu, Ya-Li; Xu, Zeng-Guang; Guo, Zhan-Yun

    2016-08-15

    Relaxin-3 is an insulin/relaxin superfamily neuropeptide involved in the regulation of food intake and stress response via activation of its cognate receptor RXFP3, an A-class G protein-coupled receptor (GPCR). In recent studies, a highly conserved ExxxD motif essential for binding of relaxin-3 has been identified at extracellular end of the second transmembrane domain (TMD2) of RXFP3. For most of the A-class GPCRs, a highly conserved negatively charged Asp residue (Asp(2.50) using Ballesteros-Weinstein numbering and Asp128 in human RXFP3) is present at the middle of TMD2. To elucidate function of the conserved transmembrane Asp128, in the present work we replaced it with other residues and the resultant RXFP3 mutants all retained quite high ligand-binding potency, but their activation and agonist-induced internalization were abolished or drastically decreased. Thus, the negatively charged transmembrane Asp128 controlled transduction of agonist-binding information from the extracellular region to the intracellular region through maintaining RXFP3 in a metastable state for efficient conformational change induced by binding of an agonist. PMID:27353281

  5. Chlorogenic acid increased 5-hydroxymethylfurfural formation when heating fructose alone or with aspartic acid at two pH levels.

    Science.gov (United States)

    Zhang, Zhenhua; Zou, Yueyu; Wu, Taigang; Huang, Caihuan; Pei, Kehan; Zhang, Guangwen; Lin, Xiaohua; Bai, Weibin; Ou, Shiyi

    2016-01-01

    Chlorogenic acid (CGA) is a phenolic acid that ubiquitously exists in fruits. This work aims to investigate whether and how CGA influences HMF formation during heating fructose alone, or with an amino acid. The results showed that that CGA increased 5-hydroxymethylfurfural (HMF) formation. At pH 5.5 and 7.0, the addition of 5.0 μmol/ml CGA increased HMF formation by 49.4% and 25.2%, respectively when heating fructose alone, and by 9.0% and 16.7%, respectively when heating fructose with aspartic acid. CGA significantly increased HMF formation by promoting 3-deoxosone formation, and its conversion to HMF by inhibiting HMF elimination, especially in the Maillard reaction system. A comparison of the catalytic capacity of CGA with its six analogous compounds showed that both its di-hydroxyphenyl and carboxyl groups function in increasing HMF formation. PMID:26213045

  6. Poly(ethylenimine)-grafted-poly[(aspartic acid)-co-lysine]:A Non-viral Polymer with Potential for DNA Delivery

    Institute of Scientific and Technical Information of China (English)

    Zhi YANG; Gu Ping TANG

    2004-01-01

    A biodegradable gene transfer vector, poly(ethylenimine)-grafted-poly[(aspartic acid)-co-lysine] has been developed by thermal polycondensation of aspartic acid and lysine, and branch poly(ethylenimine) (Mw less than 600) was grafted to the backbone. The polymer was characterized by 1H NMR. It appeared lower cytotoxity compared to poly(ethylenimine) (25KDa), which was quantified by MTT assay. Electrophoresis indicated that the polymer could retardate DNA at N/P ratio 1.2-1.8 (w/w). Transfection efficiency of the complexes was studied in NT2 cell lines. It was 1.5 fold higher than molecular weight PEI (Mw = 25KDa).

  7. Immobilization of Escherichia coli Cells Containing Aspartase Activity with Polyurethane and Its Application for l-Aspartic Acid Production

    OpenAIRE

    Fusee, Murray C.; Swann, Wayne E.; Calton, Gary J.

    1981-01-01

    Whole cells of Escherichia coli containing aspartase activity were immobilized by mixing a cell suspension with a liquid isocyanate-capped polyurethane prepolymer (Hypol). The immobilized cell preparation was used to convert ammonium fumarate to l-aspartic acid. Properties of the immobilized E. coli cells containing aspartase were investigated with a batch reactor. A 1.67-fold increase in the l-aspartic acid production rate was observed at 37°C as compared to 25°C operating temperature. The p...

  8. Application and appreciation of chemical sand fixing agent-poly (aspartic acid) and its composites

    Energy Technology Data Exchange (ETDEWEB)

    Yang Jun; Cao Hui; Wang Fang [Beijing Key Laboratory of Bioprocess, Beijing University of Chemical Technology, Beijing 100029 (China); Tan Tianwei [Beijing Key Laboratory of Bioprocess, Beijing University of Chemical Technology, Beijing 100029 (China)], E-mail: twtan@mail.buct.edu.cn

    2007-12-15

    The sand fixing agent-poly (aspartic acid) (PASP) and its composites were applied in the field by two forms (spraying around by PASP solution and PASP powder directly). It was found that the sand fixing effect in powder form was not as good as in solution form, but it was more practical in dry region. It needed 9, 6 and 7 days for PASP, xanthan gum-PASP (X2) and ethyl cellulose-PASP (E3) to attain the maximal mechanical strength after they were applied, respectively. The sand fixing effect decreased when the material was subjected to repeated hydration-dehydration cycles and the material had no negative influence on plant growth. The PASP and its composites had water-retaining ability and could reduce the water evaporation. - The sand fixing agent was applied in powder form and it had no negative influence on plant growth.

  9. Application and appreciation of chemical sand fixing agent-poly (aspartic acid) and its composites

    International Nuclear Information System (INIS)

    The sand fixing agent-poly (aspartic acid) (PASP) and its composites were applied in the field by two forms (spraying around by PASP solution and PASP powder directly). It was found that the sand fixing effect in powder form was not as good as in solution form, but it was more practical in dry region. It needed 9, 6 and 7 days for PASP, xanthan gum-PASP (X2) and ethyl cellulose-PASP (E3) to attain the maximal mechanical strength after they were applied, respectively. The sand fixing effect decreased when the material was subjected to repeated hydration-dehydration cycles and the material had no negative influence on plant growth. The PASP and its composites had water-retaining ability and could reduce the water evaporation. - The sand fixing agent was applied in powder form and it had no negative influence on plant growth

  10. Formation of haloacetamides during chlorination of dissolved organic nitrogen aspartic acid

    Energy Technology Data Exchange (ETDEWEB)

    Chu Wenhai, E-mail: 1world1water@tongji.edu.cn [State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092 (China); Gao Naiyun [State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092 (China); Deng Yang, E-mail: yang.deng@upr.edu [Department of Civil Engineering and Surveying, University of Puerto Rico, P.O. Box 9041, Mayaguez, Puerto Rico, 00681-9041 (Puerto Rico)

    2010-01-15

    The stability of haloacetamides (HAcAms) such as dichloroacetamide (DCAcAm) and trichloroacetamide (TCAcAm) was studied under different experimental conditions. The yield of HAcAms during aspartic acid (Asp) chlorination was measured at different molar ratio of chlorine atom to nitrogen atom (Cl/N), pH and dissolved organic carbon (DOC) mainly consisted of humic acid (HA) mixture. Ascorbic acid showed a better capacity to prevent the decay of DCAcAm and TCAcAm than the other two dechlorinating agents, thiosulfate and sodium sulfite. Lower Cl/N favored the DCAcAm formation, implying that breakpoint chlorination might minimize its generation. The pH decrease could lower the concentration of DCAcAm but favored dichloroacetonitrile (DCAN) formation. DCAcAm yield was sensitive to the DOC due to higher chlorine consumption caused by HA mixture. Two possible pathways of DCAcAm formation during Asp chlorination were proposed. Asp was an important precursor of DCAN, DCAcAm and dichloroacetic acid (DCAA), and thus removal of Asp before disinfection may be a method to prevent the formation of DCAcAm, DCAN and DCAA.

  11. Quantum Computational Calculations of the Ionization Energies of Acidic and Basic Amino Acids: Aspartate, Glutamate, Arginine, Lysine, and Histidine

    Science.gov (United States)

    de Guzman, C. P.; Andrianarijaona, M.; Lee, Y. S.; Andrianarijaona, V.

    An extensive knowledge of the ionization energies of amino acids can provide vital information on protein sequencing, structure, and function. Acidic and basic amino acids are unique because they have three ionizable groups: the C-terminus, the N-terminus, and the side chain. The effects of multiple ionizable groups can be seen in how Aspartate's ionizable side chain heavily influences its preferred conformation (J Phys Chem A. 2011 April 7; 115(13): 2900-2912). Theoretical and experimental data on the ionization energies of many of these molecules is sparse. Considering each atom of the amino acid as a potential departing site for the electron gives insight on how the three ionizable groups affect the ionization process of the molecule and the dynamic coupling between the vibrational modes. In the following study, we optimized the structure of each acidic and basic amino acid then exported the three dimensional coordinates of the amino acids. We used ORCA to calculate single point energies for a region near the optimized coordinates and systematically went through the x, y, and z coordinates of each atom in the neutral and ionized forms of the amino acid. With the calculations, we were able to graph energy potential curves to better understand the quantum dynamic properties of the amino acids. The authors thank Pacific Union College Student Association for providing funds.

  12. A route to anionic hydrophilic films of copolymers of l-leucine, l-aspartic acid and l-aspartic acid esters

    NARCIS (Netherlands)

    Sederel, W.L.; Bantjes, A.; Feijen, J.

    1975-01-01

    A series of copolymers of l-leucine and β-benzyl-l-aspartate [Leu/Asp(OBz)] covering the range 30–70 mol % of l-leucine, was synthesized by the N-carboxyanhydride (NCA) method. The copolymers were characterized by elemental analysis, infra-red spectroscopy and viscometry. For all compositions high m

  13. IRBIT Interacts with the Catalytic Core of Phosphatidylinositol Phosphate Kinase Type Iα and IIα through Conserved Catalytic Aspartate Residues.

    Directory of Open Access Journals (Sweden)

    Hideaki Ando

    Full Text Available Phosphatidylinositol phosphate kinases (PIPKs are lipid kinases that generate phosphatidylinositol 4,5-bisphosphate (PI(4,5P2, a critical lipid signaling molecule that regulates diverse cellular functions, including the activities of membrane channels and transporters. IRBIT (IP3R-binding protein released with inositol 1,4,5-trisphosphate is a multifunctional protein that regulates diverse target proteins. Here, we report that IRBIT forms signaling complexes with members of the PIPK family. IRBIT bound to all PIPK isoforms in heterologous expression systems and specifically interacted with PIPK type Iα (PIPKIα and type IIα (PIPKIIα in mouse cerebellum. Site-directed mutagenesis revealed that two conserved catalytic aspartate residues of PIPKIα and PIPKIIα are involved in the interaction with IRBIT. Furthermore, phosphatidylinositol 4-phosphate, Mg2+, and/or ATP interfered with the interaction, suggesting that IRBIT interacts with catalytic cores of PIPKs. Mutations of phosphorylation sites in the serine-rich region of IRBIT affected the selectivity of its interaction with PIPKIα and PIPKIIα. The structural flexibility of the serine-rich region, located in the intrinsically disordered protein region, is assumed to underlie the mechanism of this interaction. Furthermore, in vitro binding experiments and immunocytochemistry suggest that IRBIT and PIPKIα interact with the Na+/HCO3- cotransporter NBCe1-B. These results suggest that IRBIT forms signaling complexes with PIPKIα and NBCe1-B, whose activity is regulated by PI(4,5P2.

  14. Aspartic acid racemization rate in narwhal (Monodon monoceros) eye lens nuclei estimated by counting of growth layers in tusks

    DEFF Research Database (Denmark)

    Garde, Eva; Heide-Jørgensen, Mads Peter; Ditlevsen, Susanne;

    2012-01-01

    ) technique has been used in age estimation studies of cetaceans, including narwhals. The purpose of this study was to estimate a species-specific racemization rate for narwhals by regressing aspartic acid D/L ratios in eye lens nuclei against growth layer groups in tusks (n=9). Two racemization rates were...

  15. Collagen turnover in normal and degenerate human intervertebral discs as determined by the racemization of aspartic acid

    NARCIS (Netherlands)

    Sivan, S.-S.; Wachtel, E.; Tsitron, E.; Sakkee, N.; Ham, F. van der; Groot, J.de; Roberts, S.; Maroudas, A.

    2008-01-01

    Knowledge of rates of protein turnover is important for a quantitative understanding of tissue synthesis and catabolism. In this work, we have used the racemization of aspartic acid as a marker for the turnover of collagen obtained from healthy and pathological human intervertebral disc matrices. We

  16. Antagonizing Effects of Aspartic Acid against Ultraviolet A-Induced Downregulation of the Stemness of Human Adipose Tissue-Derived Mesenchymal Stem Cells.

    Directory of Open Access Journals (Sweden)

    Kwangseon Jung

    Full Text Available Ultraviolet A (UVA irradiation is responsible for a variety of changes in cell biology. The purpose of this study was to investigate effects of aspartic acid on UVA irradiation-induced damages in the stemness properties of human adipose tissue-derived mesenchymal stem cells (hAMSCs. Furthermore, we elucidated the UVA-antagonizing mechanisms of aspartic acid. The results of this study showed that aspartic acid attenuated the UVA-induced reduction of the proliferative potential and stemness of hAMSCs, as evidenced by increased proliferative activity in the 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide (MTT assay and upregulation of stemness-related genes OCT4, NANOG, and SOX2 in response to the aspartic acid treatment. UVA-induced reduction in the mRNA level of hypoxia-inducible factor (HIF-1α was also significantly recovered by aspartic acid. In addition, the antagonizing effects of aspartic acid against the UVA effects were found to be mediated by reduced production of PGE2 through the inhibition of JNK and p42/44 MAPK. Taken together, these findings show that aspartic acid improves reduced stemness of hAMSCs induced by UVA and its effects are mediated by upregulation of HIF-1α via the inhibition of PGE2-cAMP signaling. In addition, aspartic acid may be used as an antagonizing agent to mitigate the effects of UVA.

  17. Conserved aspartate and lysine residues of RcsB are required for amylovoran biosynthesis, virulence, and DNA binding in Erwinia amylovora.

    Science.gov (United States)

    Ancona, Veronica; Chatnaparat, Tiyakhon; Zhao, Youfu

    2015-08-01

    In Erwinia amylovora, the Rcs phosphorelay system is essential for amylovoran production and virulence. To further understand the role of conserved aspartate residue (D56) in the phosphor receiver (PR) domain and lysine (K180) residue in the function domain of RcsB, amino acid substitutions of RcsB mutant alleles were generated by site-directed mutagenesis and complementation of various rcs mutants were performed. A D56E substitution of RcsB, which mimics the phosphorylation state of RcsB, complemented the rcsB mutant, resulting in increased amylovoran production and gene expression, reduced swarming motility, and restored pathogenicity. In contrast, D56N and K180A or K180Q substitutions of RcsB did not complement the rcsB mutant. Electrophoresis mobility shift assays showed that D56E, but not D56N, K180Q and K180A substitutions of RcsB bound to promoters of amsG and flhD, indicating that both D56 and K180 are required for DNA binding. Interestingly, the RcsBD56E allele could also complement rcsAB, rcsBC and rcsABCD mutants with restored virulence and increased amylovoran production, indicating that RcsB phosphorylation is essential for virulence of E. amylovora. In addition, mutations of T904 and A905, but not phosphorylation mimic mutation of D876 in the PR domain of RcsC, constitutively activate the Rcs system, suggesting that phosphor transfer is required for activating the Rcs system and indicating both A905 and T904 are required for the phosphatase activity of RcsC. Our results demonstrated that RcsB phosphorylation and dephosphorylation, phosphor transfer from RcsC are essential for the function of the Rcs system, and also suggested that constitutive activation of the Rcs system could reduce the fitness of E. amylovora.

  18. Evaluation of poly (aspartic acid sodium salt) as a draw solute for forward osmosis.

    Science.gov (United States)

    Gwak, Gimun; Jung, Bokyung; Han, Sungsoo; Hong, Seungkwan

    2015-09-01

    Poly (aspartic acid sodium salt) (PAspNa) was evaluated for its potential as a novel draw solute in forward osmosis (FO). The inherent advantages of PAspNa, such as good water solubility, high osmotic pressure, and nontoxicity, were first examined through a series of physicochemical analyses and atomic-scale molecular dynamics simulations. Then, lab-scale FO tests were performed to evaluate its suitability in practical processes. Compared to other conventional inorganic solutes, PAspNa showed comparable water flux but significantly lower reverse solute flux, demonstrating its suitability as a draw solute. Moreover, fouling experiments using synthetic wastewater as a feed solution demonstrated that PAspNa reversely flowed to the feed side reduced inorganic scaling on the membrane active layer. The recyclability of PAspNa was studied using both nanofiltration (NF) and membrane distillation (MD) processes, and the results exhibited its ease of recovery. This research reported the feasibility and applicability of FO-NF or FO-MD processes using PAspNa for wastewater reclamation and brackish water desalination.

  19. Finding a Leucine in a Haystack: Searching the Proteome for ambigous Leucine-Aspartic Acid motifs

    KAUST Repository

    Arold, Stefan T.

    2016-01-25

    Leucine-aspartic acid (LD) motifs are short helical protein-protein interaction motifs involved in cell motility, survival and communication. LD motif interactions are also implicated in cancer metastasis and are targeted by several viruses. LD motifs are notoriously difficult to detect because sequence pattern searches lead to an excessively high number of false positives. Hence, despite 20 years of research, only six LD motif–containing proteins are known in humans, three of which are close homologues of the paxillin family. To enable the proteome-wide discovery of LD motifs, we developed LD Motif Finder (LDMF), a web tool based on machine learning that combines sequence information with structural predictions to detect LD motifs with high accuracy. LDMF predicted 13 new LD motifs in humans. Using biophysical assays, we experimentally confirmed in vitro interactions for four novel LD motif proteins. Thus, LDMF allows proteome-wide discovery of LD motifs, despite a highly ambiguous sequence pattern. Functional implications will be discussed.

  20. Evaluation of poly (aspartic acid sodium salt) as a draw solute for forward osmosis.

    Science.gov (United States)

    Gwak, Gimun; Jung, Bokyung; Han, Sungsoo; Hong, Seungkwan

    2015-09-01

    Poly (aspartic acid sodium salt) (PAspNa) was evaluated for its potential as a novel draw solute in forward osmosis (FO). The inherent advantages of PAspNa, such as good water solubility, high osmotic pressure, and nontoxicity, were first examined through a series of physicochemical analyses and atomic-scale molecular dynamics simulations. Then, lab-scale FO tests were performed to evaluate its suitability in practical processes. Compared to other conventional inorganic solutes, PAspNa showed comparable water flux but significantly lower reverse solute flux, demonstrating its suitability as a draw solute. Moreover, fouling experiments using synthetic wastewater as a feed solution demonstrated that PAspNa reversely flowed to the feed side reduced inorganic scaling on the membrane active layer. The recyclability of PAspNa was studied using both nanofiltration (NF) and membrane distillation (MD) processes, and the results exhibited its ease of recovery. This research reported the feasibility and applicability of FO-NF or FO-MD processes using PAspNa for wastewater reclamation and brackish water desalination. PMID:26005789

  1. Measurement of aspartic acid in oilseed rape leaves under herbicide stress using near infrared spectroscopy and chemometrics.

    Science.gov (United States)

    Zhang, Chu; Kong, Wenwen; Liu, Fei; He, Yong

    2016-01-01

    Oilseed rape is used as both food and a renewable energy resource. Physiological parameters, such as the amino acid aspartic acid, can indicate the growth status of oilseed rape. Traditional detection methods are laborious, time consuming, costly, and not usable in the field. Here, we investigate near infrared spectroscopy (NIRS) as a fast and non-destructive detection method of aspartic acid in oilseed rape leaves under herbicide stress. Different spectral pre-processing methods were compared for optimal prediction performance. The variable selection methods were applied for relevant variable selection, including successive projections algorithm (SPA), Monte Carlo-uninformative variable elimination (MC-UVE) and random frog (RF). The selected effective wavelengths (EWs) were used as input by multiple linear regression (MLR), partial least squares (PLS) and least-square support vector machine (LS-SVM). The best predictive performance was achieved by SPA-LS-SVM (Raw) model using 22 EWs, and the prediction results were Rp = 0.9962 and RMSEP = 0.0339 for the prediction set. The result indicated that NIR combined with LS-SVM is a powerful new method to detect aspartic acid in oilseed rape leaves under herbicide stress. PMID:27441244

  2. Computational study on 3D structure of L-aspartic acid and L-glutamic acid: molecular descriptors and properties

    Directory of Open Access Journals (Sweden)

    Stefaniu Amalia

    2016-06-01

    Full Text Available The aim of this work is to provide a comprehensive and complex analysis of molecular descriptors and properties of two similar amino acids, L-Aspartic acid and L-Glutamic acid, using a software tool for calculations and properties predictions. As amino acids are model compounds for predicting the physical-chemical properties and behavior of biological, larger molecules as peptides or proteins, researches were focused on providing accurate mechanical calculations using: molecular/mechanical methods. Our study aims to initiate a linear scaling approach, by dividing a large system into small subsystems and performing the calculations for each, individually, then, embedding and correcting the information globally. The calculations were performed on the 3D structure of the studied amino acids that were first generated, as CPK model, and optimized by energy minimization. A comparative assay on their topological, molecular descriptors and properties was conducted, in vacuum and in water, using the Hartree-Fock model and second-order Møller-Plesset perturbation theory MP2 for predicting structure, energy and property calculations with Spartan’14 software. Values of molecular properties such as area, volume, polar surface area, polarizability, ovality, logP, dipole moment, HOMO-LUMO gap, distances and angles between atoms, were obtained. The results have been interpreted in terms of electronic effects of side chain groups, molecular deformability, steric factors and reactivity. This approach can be extended to other amino acids in order to predict protein-ligand interactions, important aspects in drug design studies and protein engineering.

  3. Solid-State Synthesis, Characterization, and Biological Activity of the Bioinorganic Complex of Aspartic Acid and Arsenic Triiodide

    Directory of Open Access Journals (Sweden)

    Guo-Qing Zhong

    2013-01-01

    Full Text Available The bioinorganic complex of aspartic acid and arsenic triiodide was synthesized by a solid-state reaction at room temperature. The formula of the complex is AsI3[HOOCCH2CH(NH2COOH]2.5. The crystal structure of the complex belongs to monoclinic system with lattice parameters: a=1.0019 nm, b=1.5118 nm, c=2.1971 nm, and β=100.28°. The infrared spectra can demonstrate the complex formation between the arsenic ion and aspartic acid, and the complex may be a dimer with bridge structure. The result of primary biological test indicates that the complex possesses better biological activity for the HL-60 cells of the leukemia than arsenic triiodide.

  4. Proton transport properties of poly(aspartic acid) with different average molecular weights

    International Nuclear Information System (INIS)

    Research highlights: → Seven polymers with different average molecular weights were synthesized. → The proton conductivity depended on the number-average degree of polymerization. → The difference of the proton conductivities was more than one order of magnitude. → The number-average molecular weight contributed to the stability of the polymer. - Abstract: We synthesized seven partially protonated poly(aspartic acids)/sodium polyaspartates (P-Asp) with different average molecular weights to study their proton transport properties. The number-average degree of polymerization (DP) for each P-Asp was 30 (P-Asp30), 115 (P-Asp115), 140 (P-Asp140), 160 (P-Asp160), 185 (P-Asp185), 205 (P-Asp205), and 250 (P-Asp250). The proton conductivity depended on the number-average DP. The maximum and minimum proton conductivities under a relative humidity of 70% and 298 K were 1.7 . 10-3 S cm-1 (P-Asp140) and 4.6 . 10-4 S cm-1 (P-Asp250), respectively. Differential thermogravimetric analysis (TG-DTA) was carried out for each P-Asp. The results were classified into two categories. One exhibited two endothermic peaks between t = (270 and 300) oC, the other exhibited only one peak. The P-Asp group with two endothermic peaks exhibited high proton conductivity. The high proton conductivity is related to the stability of the polymer. The number-average molecular weight also contributed to the stability of the polymer.

  5. N-Methyl D-Aspartic Acid (NMDA Receptors and Depression

    Directory of Open Access Journals (Sweden)

    Enver Yusuf Sivrioglu

    2009-06-01

    Full Text Available The monoaminergic hypothesis of depression has provided the basis for extensive research into the pathophysiology of mood disorders and has been of great significance for the development of effective antidepressants. Current antidepressant treatments not only increase serotonin and/or noradrenaline bioavailability but also originate adaptive changes increasing synaptic plasticity. Novel approaches to depression and to antidepressant therapy are now focused on intracellular targets that regulate neuroplasticity and cell survival. Accumulating evidence indicates that there is an anatomical substrate for such a devastating neuropsychiatric disease as major depression. Loss of synaptic plasticity and hippocampal atrophy appear to be prominent features of this highly prevalent disorder. A combination of genetic susceptibility and environmental factors make hippocampal neurons more vulnerable to stress. Abundant experimental evidence indicates that stress causes neuronal damage in brain regions, notably in hippocampal subfields. Stress-induced activation of glutamatergic transmission may induce neuronal cell death through excessive stimulation of N-methyl-D-aspartic acid (NMDA receptors. Recent studies mention that the increase of nitric oxide synthesis and inflammation in major depression may contribute to neurotoxicity through NMDA receptor. Both standard antidepressants and NMDA receptor antagonists are able to prevent stress-induced neuronal damage. NMDA antagonists are effective in widely used animal models of depression and some of them appear to be effective also in the few clinical trials performed to date. We are still far from understanding the complex cellular and molecular events involved in mood disorders. There appears to be an emerging role for glutamate neurotransmission in the search for the pathogenesis of major depression. Attenuation of NMDA receptor function mechanism appears to be a promising target in the search for a more

  6. Immobilization of Escherichia coli Cells Containing Aspartase Activity with Polyurethane and Its Application for l-Aspartic Acid Production

    Science.gov (United States)

    Fusee, Murray C.; Swann, Wayne E.; Calton, Gary J.

    1981-01-01

    Whole cells of Escherichia coli containing aspartase activity were immobilized by mixing a cell suspension with a liquid isocyanate-capped polyurethane prepolymer (Hypol). The immobilized cell preparation was used to convert ammonium fumarate to l-aspartic acid. Properties of the immobilized E. coli cells containing aspartase were investigated with a batch reactor. A 1.67-fold increase in the l-aspartic acid production rate was observed at 37°C as compared to 25°C operating temperature. The pH optimum was broad, ranging from 8.5 to 9.2. Increasing the concentration of ammonium fumarate to 1.5 M from 1.0 M negatively affected the reaction rate. l-Aspartic acid was produced at an average rate of 2.18 × 10−4 mol/min per g (wet weight) of immobilized E. coli cells with a 37°C substrate solution consisting of 1.0 M ammonium fumarate with 1 mM Mg2+ (pH 9.0). PMID:16345865

  7. Exotoxin A of Pseudomonas aeruginosa: substitution of glutamic acid 553 with aspartic acid drastically reduces toxicity and enzymatic activity.

    OpenAIRE

    Douglas, C M; Collier, R J

    1987-01-01

    Glutamic acid 553 of Pseudomonas aeruginosa exotoxin A (ETA) has been identified by photoaffinity labeling as a residue within the NAD binding site (S.F. Carroll and R.J. Collier, J. Biol. Chem. 262:8707-8711, 1987). To explore the function of Glu-553 we used oligonucleotide-directed mutagenesis to replace this residue with Asp in cloned ETA and expressed the mutant gene in Escherichia coli K-12. ADP-ribosylation activity of Asp-553 ETA in cell extracts was about 1,800-fold lower and toxicity...

  8. [Effect of excitant amino acid antagonists on glutamate receptors in the locust and on convulsions induced by glutamate, aspartate, kynurenine and quinolinic acid in mice].

    Science.gov (United States)

    Ryzhov, I V; Slepokurov, M V; Lapin, I P; Mandel'shtam, Iu E; Aleksandrov, V G

    1986-03-01

    All excitatory amino acid antagonists studied: diethyl esters of aspartic (DEEA) and glutamic (DEEG) acids, 2-amino-3-phosphono-propionic acid (APPA) and 2-amino-4-phosphono-butanoic acid (APBA), diminished the amplitude of excitatory postsynaptic potentials (EPP) of the locust (Locusta migratoria migratorioides) muscle fibers and arbitrary blocked glutamate (GLU) and aspartate (ASP) responses. Kynurenine (KYN) and quinolinic (QUI) acid had no effect on EPP even at a concentration of 2 X 10(-2) M. The antagonists were not strictly selective against intracerebroventricularly administered endogenous convulsants: GLU, ASP, KYN and QUI and in simulation of experimental seizures in mice. The antagonists structurally similar to ASP prevented ASP- and KYN-induced seizures in lower doses than GLU derivatives. Anti-KYN, but not anti-QUI DEEA, DEEG, APPA and APBA efficacy suggests that KYN and QUI act on different structures or binding sites. PMID:2869799

  9. Comments on the paper: 'Optical reflectance, optical refractive index and optical conductivity measurements of nonlinear optics for L-aspartic acid nickel chloride single crystal'

    Science.gov (United States)

    Srinivasan, Bikshandarkoil R.; Naik, Suvidha G.; Dhavskar, Kiran T.

    2016-02-01

    We argue that the 'L-aspartic acid nickel chloride' crystal reported by the authors of the title paper (Optics Communications, 291 (2013) 304-308) is actually the well-known diaqua(L-aspartato)nickel(II) hydrate crystal.

  10. Structural and Biochemical Characterization of a Copper-Binding Mutant of the Organomercurial Lyase MerB: Insight into the Key Role of the Active Site Aspartic Acid in Hg-Carbon Bond Cleavage and Metal Binding Specificity.

    Science.gov (United States)

    Wahba, Haytham M; Lecoq, Lauriane; Stevenson, Michael; Mansour, Ahmed; Cappadocia, Laurent; Lafrance-Vanasse, Julien; Wilkinson, Kevin J; Sygusch, Jurgen; Wilcox, Dean E; Omichinski, James G

    2016-02-23

    In bacterial resistance to mercury, the organomercurial lyase (MerB) plays a key role in the detoxification pathway through its ability to cleave Hg-carbon bonds. Two cysteines (C96 and C159; Escherichia coli MerB numbering) and an aspartic acid (D99) have been identified as the key catalytic residues, and these three residues are conserved in all but four known MerB variants, where the aspartic acid is replaced with a serine. To understand the role of the active site serine, we characterized the structure and metal binding properties of an E. coli MerB mutant with a serine substituted for D99 (MerB D99S) as well as one of the native MerB variants containing a serine residue in the active site (Bacillus megaterium MerB2). Surprisingly, the MerB D99S protein copurified with a bound metal that was determined to be Cu(II) from UV-vis absorption, inductively coupled plasma mass spectrometry, nuclear magnetic resonance, and electron paramagnetic resonance studies. X-ray structural studies revealed that the Cu(II) is bound to the active site cysteine residues of MerB D99S, but that it is displaced following the addition of either an organomercurial substrate or an ionic mercury product. In contrast, the B. megaterium MerB2 protein does not copurify with copper, but the structure of the B. megaterium MerB2-Hg complex is highly similar to the structure of the MerB D99S-Hg complexes. These results demonstrate that the active site aspartic acid is crucial for both the enzymatic activity and metal binding specificity of MerB proteins and suggest a possible functional relationship between MerB and its only known structural homologue, the copper-binding protein NosL.

  11. Development of novel radiogallium-labeled bone imaging agents using oligo-aspartic acid peptides as carriers.

    Directory of Open Access Journals (Sweden)

    Kazuma Ogawa

    Full Text Available (68Ga (T 1/2 = 68 min, a generator-produced nuclide has great potential as a radionuclide for clinical positron emission tomography (PET. Because poly-glutamic and poly-aspartic acids have high affinity for hydroxyapatite, to develop new bone targeting (68Ga-labeled bone imaging agents for PET, we used 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA as a chelating site and conjugated aspartic acid peptides of varying lengths. Subsequently, we compared Ga complexes, Ga-DOTA-(Aspn (n = 2, 5, 8, 11, or 14 with easy-to-handle (67Ga, with the previously described (67Ga-DOTA complex conjugated bisphosphonate, (67Ga-DOTA-Bn-SCN-HBP. After synthesizing DOTA-(Aspn by a Fmoc-based solid-phase method, complexes were formed with (67Ga, resulting in (67Ga-DOTA-(Aspn with a radiochemical purity of over 95% after HPLC purification. In hydroxyapatite binding assays, the binding rate of (67Ga-DOTA-(Aspn increased with the increase in the length of the conjugated aspartate peptide. Moreover, in biodistribution experiments, (67Ga-DOTA-(Asp8, (67Ga-DOTA-(Asp11, and (67Ga-DOTA-(Asp14 showed high accumulation in bone (10.5 ± 1.5, 15.1 ± 2.6, and 12.8 ± 1.7% ID/g, respectively but were barely observed in other tissues at 60 min after injection. Although bone accumulation of (67Ga-DOTA-(Aspn was lower than that of (67Ga-DOTA-Bn-SCN-HBP, blood clearance of (67Ga-DOTA-(Aspn was more rapid. Accordingly, the bone/blood ratios of (67Ga-DOTA-(Asp11 and (67Ga-DOTA-(Asp14 were comparable with those of (67Ga-DOTA-Bn-SCN-HBP. In conclusion, these data provide useful insights into the drug design of (68Ga-PET tracers for the diagnosis of bone disorders, such as bone metastases.

  12. Subcellular distribution of N-methyl-D-aspartic acid receptor subunit 1 in neural stem cells within subventricular zone of adult rats

    Institute of Scientific and Technical Information of China (English)

    Zhining Li; Wenlong Lü; Hongyan Dong; Hongbin Fan; Ruiguo Dong; Tiejun Xu

    2011-01-01

    The subcellular localization of N-methyl-D-aspartic acid receptor subunit 1 in neural stem cells of the subventricular zone of adult rats was detected using electron microscopy, following immunohistochemistry and immunogold-silver double staining. Results confirmed the presence of neural stem cells in the subventricular zone, which is a key neurogenic region in the central nervous system of adult mammals. The expression of N-methyl-D-aspartic acid receptor subunit 1 was higher than that of nestin and mainly distributed in the cell membrane, cytoplasm, rough endoplasmic reticulum and Golgi complex of neural stem cells.

  13. Effect of heavy metals and phenol on bacterial decolourisation and COD reduction of sucrose-aspartic acid Maillard product

    Institute of Scientific and Technical Information of China (English)

    Sangeeta Yadav; Ram Chandra

    2013-01-01

    Melanodins are amino-carbonyl complex,predominantly present in sugarcane molasses based distillery wastewater as major source of colourant.The microbial decolourisation of melanoidin is a challenge due to its binding property with other co-pollutants of distillery waste.Results revealed that the presence of Zn2+ (2.00-20.00 mg/L) in melanoidin solution (1200 mg/L) stimulated the bacterial growth and sucrose-aspartic acid Maillard product (SAA) decolourisation as compared to control,while Fe3+ and Mn2+ at the same concentration inhibited the process.However,the presence of phenol (100 mg/L) along with Zn2+,Fe3+ and Mn2+ suppressed the bacterial growth,SAA decolourisation and MnP activity.The shrinkage and reduced number of bacterial cell count at higher concentration of heavy metals in presence of phenol was also observed under scanning electron microscope.

  14. Synthesis, characterization and application of a novel chemical sand-fixing agent-poly(aspartic acid) and its composites

    Energy Technology Data Exchange (ETDEWEB)

    Yang Jun [Beijing Key Laboratory of Bioprocess, Beijing University of Chemical Technology, Beijing 100029 (China); Wang Fang [Beijing Key Laboratory of Bioprocess, Beijing University of Chemical Technology, Beijing 100029 (China); Fang Li [Beijing Key Laboratory of Bioprocess, Beijing University of Chemical Technology, Beijing 100029 (China); Tan Tianwei [Beijing Key Laboratory of Bioprocess, Beijing University of Chemical Technology, Beijing 100029 (China)]. E-mail: twtan@mail.buct.edu.cn

    2007-09-15

    A novel sand-fixing agent-poly(aspartic acid) and its composites were synthesized to improve sand particles compressive strength and anti-wind erosion properties. The relationship between the concentration of sand-fixing agent and the sand-fixing properties was studied by three kinds of aging tests. Some composites were choose to improve the sand-fixing property and the composition of 40% xanthan gum and 60% ethyl cellulose were chosen to compare sand-fixing property with lignosulfonate. The results showed that the sand-fixing and water-retaining properties of xanthan gum and ethyl cellulose composites were better than that of lignosulfonate. The biodegradability experiment showed that the PASP and its composites were environment-friendly products and the field test showed that the PASP composites could improve wind erosion disturbance. - A novel biodegradability polymer significantly improved sand particles' compressive strength and anti-wind erosion properties.

  15. Synthesis, characterization and application of a novel chemical sand-fixing agent-poly(aspartic acid) and its composites

    International Nuclear Information System (INIS)

    A novel sand-fixing agent-poly(aspartic acid) and its composites were synthesized to improve sand particles compressive strength and anti-wind erosion properties. The relationship between the concentration of sand-fixing agent and the sand-fixing properties was studied by three kinds of aging tests. Some composites were choose to improve the sand-fixing property and the composition of 40% xanthan gum and 60% ethyl cellulose were chosen to compare sand-fixing property with lignosulfonate. The results showed that the sand-fixing and water-retaining properties of xanthan gum and ethyl cellulose composites were better than that of lignosulfonate. The biodegradability experiment showed that the PASP and its composites were environment-friendly products and the field test showed that the PASP composites could improve wind erosion disturbance. - A novel biodegradability polymer significantly improved sand particles' compressive strength and anti-wind erosion properties

  16. Insulin Aspart in the Management of Diabetes Mellitus: 15 Years of Clinical Experience

    OpenAIRE

    Hermansen, Kjeld; Bohl, Mette; Schioldan, Anne Grethe

    2015-01-01

    Limiting excessive postprandial glucose excursions is an important component of good overall glycemic control in diabetes mellitus. Pharmacokinetic studies have shown that insulin aspart, which is structurally identical to regular human insulin except for the replacement of a single proline amino acid with an aspartic acid residue, has a more physiologic time–action profile (i.e., reaches a higher peak and reaches that peak sooner) than regular human insulin. As expected with this improved ph...

  17. Aspartic acid racemization rate in narwhal (Monodon monoceros eye lens nuclei estimated by counting of growth layers in tusks

    Directory of Open Access Journals (Sweden)

    Eva Garde

    2012-11-01

    Full Text Available Ages of marine mammals have traditionally been estimated by counting dentinal growth layers in teeth. However, this method is difficult to use on narwhals (Monodon monoceros because of their special tooth structures. Alternative methods are therefore needed. The aspartic acid racemization (AAR technique has been used in age estimation studies of cetaceans, including narwhals. The purpose of this study was to estimate a species-specific racemization rate for narwhals by regressing aspartic acid d/l ratios in eye lens nuclei against growth layer groups in tusks (n=9. Two racemization rates were estimated: one by linear regression (r2=0.98 based on the assumption that age was known without error, and one based on a bootstrap study, taking into account the uncertainty in the age estimation (r2 between 0.88 and 0.98. The two estimated 2kAsp values were identical up to two significant figures. The 2k Asp value from the bootstrap study was found to be 0.00229±0.000089 SE, which corresponds to a racemization rate of 0.00114−yr±0.000044 SE. The intercept of 0.0580±0.00185 SE corresponds to twice the (d/l0 value, which is then 0.0290±0.00093 SE. We propose that this species-specific racemization rate and (d/l0 value be used in future AAR age estimation studies of narwhals, but also recommend the collection of tusks and eyes of narwhals for further improving the (d/l0 and 2kAsp estimates obtained in this study.

  18. L-Aspartic and l-glutamic acid ester-based ProTides of anticancer nucleosides: Synthesis and antitumoral evaluation.

    Science.gov (United States)

    Gao, Ling-Jie; De Jonghe, Steven; Daelemans, Dirk; Herdewijn, Piet

    2016-05-01

    A series of novel aryloxyphosphoramidate nucleoside prodrugs based on l-aspartic acid and l-glutamic acid as amino acid motif has been synthesized and evaluated for antitumoral activity. Depending on the cancer cell line studied and on the nature of the parent nucleoside compound (gemcitabine, 5-iodo-2'-deoxy-uridine, floxuridine or brivudin), the corresponding ProTides are endowed with an improved or decreased cytotoxic activity. PMID:27032331

  19. Surface aggregation of urinary proteins and aspartic acid-rich peptides on the faces of calcium oxalate monohydrate investigated by in situ force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Weaver, M L; Qiu, S R; Hoyer, J R; Casey, W H; Nancollas, G H; De Yoreo, J J

    2008-05-28

    The growth of calcium oxalate monohydrate in the presence of Tamm-Horsfall protein (THP), osteopontin (OPN), and the 27-residue synthetic peptides (DDDS){sub 6}DDD and (DDDG){sub 6}DDD [where D = aspartic acid and X = S (serine) or G (glycine)] was investigated via in situ atomic force microscopy (AFM). The results show that these three growth modulators create extensive deposits on the crystal faces. Depending on the modulator and crystal face, these deposits can occur as discrete aggregates, filamentary structures, or uniform coatings. These proteinaceous films can lead to either the inhibition or increase of the step speeds (with respect to the impurity-free system) depending on a range of factors that include peptide or protein concentration, supersaturation and ionic strength. While THP and the linear peptides act, respectively, to exclusively increase and inhibit growth on the (-101) face, both exhibit dual functionality on the (010) face, inhibiting growth at low supersaturation or high modulator concentration and accelerating growth at high supersaturation or low modulator concentration. Based on analyses of growth morphologies and dependencies of step speeds on supersaturation and protein or peptide concentration, we argue for a picture of growth modulation that accounts for the observations in terms of the strength of binding to the surfaces and steps and the interplay of electrostatic and solvent-induced forces at crystal surface.

  20. Voltammetric determination of dopamine and norepinphrine on a glassy carbon electrode modified with poly (L-aspartic acid)

    Indian Academy of Sciences (India)

    Zhangyu Yu; Xiaochun Li; Xueliang Wang; Xinying Ma; Xia Li; Kewei Cao

    2012-03-01

    A convenient and useful method for the voltammetric determination of dopamine (DA) and norepinphrine (NE) based on poly(L-aspartic acid) modified glassy carbon electrode (GCE) is reported in this paper. The modified electrode exhibits excellent electro-catalytic activities for the oxidation-reduction of DA and NE, as well as eliminating the interference of ascorbic acid (AA) and uric acid (UA). Factors influencing the detection processes are optimized and the kinetic parameters are calculated. Under the optimal conditions, the anodic peak currents of DA and NE are linear with their concentration and the detection limits (S/N = 3) are 1.0 × 10−9 mol L-1 for DA and 4.31 10−9 mol L-1 for NE, respectively. The practical application of this method is demonstrated by determining the concentration of NE and DA in injection which is commercially available with satisfactory results. Compared with other electrochemical methods, this method is simple, highly selective and sensitive.

  1. Novel class of amino acid antagonists at non-N-methyl-D-aspartic acid excitatory amino acid receptors. Synthesis, in vitro and in vivo pharmacology, and neuroprotection

    Energy Technology Data Exchange (ETDEWEB)

    Krogsgaard-Larsen, P.; Ferkany, J.W.; Nielsen, E.O.; Madsen, U.; Ebert, B.; Johansen, J.S.; Diemer, N.H.; Bruhn, T.; Beattie, D.T.; Curtis, D.R. (Royal Danish School of Pharmacy, Copenhagen (Denmark))

    1991-01-01

    The isoxazole amino acid 2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl) propionic acid (AMPA) (1), which is a highly selective agonist at the AMPA subtype of excitatory amino acid (EAA) receptors, has been used as a lead for the development of two novel EAA receptor antagonists. One of the compounds, 2-amino-3-(3-(carboxymethoxy)-5-methylisoxazol-4-yl)propionic acid (AMOA, 7), was synthesized via O-alkylation by ethyl chloroacetate of the amino acid protected AMPA derivative 4. The other compound, 2-amino-3-(2-(3-hydroxy-5-methylisoxazol-4-yl)-methyl-5-methyl-3-+ ++oxoisoxazolin -4-yl)propionic acid (AMNH, 14) was synthesized with use of 4-(chloromethyl)-3-methoxy-5-methylisoxazole (8) as the starting material. The intermediate 4-(chloromethyl)-2-(3-methoxy-5-methylisoxazol-4-yl)methyl-5-me thylisoxazolin- 3-one (11) was converted into the acetamidomalonate (12), which was stepwise deprotected to give 14. Compounds 7 and 14 were stable in aqueous solution at pH values close to physiological pH. Neither 7 nor 14 showed detectable affinities for the receptor, ion channel, or modulatory sites of the N-methyl-D-aspartic acid (NMDA) receptor complex. Quantitative receptor autoradiographic and conventional binding techniques were used to study the affinities of 7 and 14 for non-NMDA receptor sites. Both compounds were inhibitors of the binding of (3H)AMPA (IC50 = 90 and 29 microM, respectively). Compounds 14 and 7 were both very weak inhibitors of the high-affinity binding of radioactive kainic acid ((3H)KAIN). Compound 14, but not 7, was, however, shown to be an inhibitor of low-affinity (3H)KAIN binding as determined in the presence of 100 mM calcium chloride. In the rat cortical slice preparation, 7 was shown to antagonize excitation induced by 1 with some selectivity, whereas 14 proved to be a rather selective antagonist of KAIN-induced excitation.

  2. Theoretical Study on the Activity of α-COOH and β-COOH of N-Phosphoryl Aspartic Acids

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The bio-mimic reactions of N-phosphoryl amino acids are very important in the study of many biochemical processes. The difference of reactivity between α-COOH and β-COOH in phosphoryl aspartic acid was studied by theoretical study (Hartree-Fock and Density Functional methods) in this paper. The intermediates Ⅱ containing five-membered ring were more stable than Ⅲ with six-membered ring. While for intermediates Ⅲ, the isomers with six-membered ring in apical-equatorial spanning arrangement were more stable than those with di-equatorial spanning arrangement. At B3LYP/6-31G** level, it was shown that transition states Ⅳ and V involving α-COOH or β-COOH group had energy barriers of ΔE = 58.67 kJ·mol-1 and 103.94 kJ·mol-1, respectively. These results were in agreement with the experimental data. So the α-COOH group was involved in form of the intramolecular penta-coordinate phosphoric-carboxylic mixed anhydride intermediates, but not β-COOH group.

  3. Synthesis and characterization of magnetic and luminescent Fe3O4/CdTe nanocomposites using aspartic acid as linker

    Institute of Scientific and Technical Information of China (English)

    Xiu Ling Wang; Lu Wei; Guan Hong Tao; Meng Qiong Huang

    2011-01-01

    In this study, the preparation of a new kind of magnetic and luminescent Fe3O4/CdTe nanocomposites was demonstrated. Superparamagnetic Fe3O4 nanoparticles were first synthesized by hydrothermal coprecipitation of ferric and ferrous ions, followed by the modification of their surfaces with tetramethylammonium hydroxide (TMAOH) and the chemical activation with aspartic acid. The surface-modified Fe3O4 nanoparticles were then covalently coated with CdTe quantum dots (QDs), which were modified with mercaptoacetic acid (MPA), to form the Fe3O4/CdTe magnetic and luminescent nanocomposites through the coordination of the amino groups on the surfaces of Fe3O4 and the carboxyl groups on CdTe QDs. The structure and properties of as-synthesized nanocomposites were characterized. It was indicated that the nanocomposites possessed structure with an average diameter of 40-50 nm, yellow-green emission feature and room temperature ferro-magnetism. Both the fluorescence and UV-vis absorption spectra of the nanocomposites showed a blue shift comparing with those of CdTe QDs. The mechanism of the blue shift was presented. The nanocomposites retained the ferromagnetic property with a saturation magnetization of 8.9 emu/g.

  4. Ligand-functionalized degradable polyplexes formed by cationic poly(aspartic acid)-grafted chitosan-cyclodextrin conjugates

    Science.gov (United States)

    Song, Hai-Qing; Li, Rui-Quan; Duan, Shun; Yu, Bingran; Zhao, Hong; Chen, Da-Fu; Xu, Fu-Jian

    2015-03-01

    Polypeptide-based degradable polyplexes attracted considerable attention in drug delivery systems. Polysaccharides including cyclodextrin (CD), dextran, and chitosan (CS) were readily grafted with cationic poly(aspartic acid)s (PAsps). To further enhance the transfection performances of PAsp-based polyplexes, herein, different types of ligand (folic acid, FA)-functionalized degradable polyplexes were proposed based on the PAsp-grafted chitosan-cyclodextrin conjugate (CCPE), where multiple β-CDs were tied on a CS chain. The FA-functionalized CCPE (i.e., CCPE-FA) was obtained via a host-guest interaction between the CD units of CCPE and the adamantane (Ad) species of Ad-modified FA (Ad-FA). The resulting CCPE/pDNA, CCPE-FA/pDNA, and ternary CCPE-FA/CCPE/pDNA (prepared by layer-by-layer assembly) polyplexes were investigated in detail using different cell lines. The CCPE-based polyplexes displayed much higher transfection efficiencies than the CS-based polyplexes reported earlier by us. The ternary polyplexes of CCPE-FA/CCPE/pDNA produced excellent gene transfection abilities in the folate receptor (FR)-positive tumor cells. This work would provide a promising means to produce highly efficient polyplexes for future gene therapy applications.Polypeptide-based degradable polyplexes attracted considerable attention in drug delivery systems. Polysaccharides including cyclodextrin (CD), dextran, and chitosan (CS) were readily grafted with cationic poly(aspartic acid)s (PAsps). To further enhance the transfection performances of PAsp-based polyplexes, herein, different types of ligand (folic acid, FA)-functionalized degradable polyplexes were proposed based on the PAsp-grafted chitosan-cyclodextrin conjugate (CCPE), where multiple β-CDs were tied on a CS chain. The FA-functionalized CCPE (i.e., CCPE-FA) was obtained via a host-guest interaction between the CD units of CCPE and the adamantane (Ad) species of Ad-modified FA (Ad-FA). The resulting CCPE/pDNA, CCPE

  5. How to find a leucine in a haystack? Structure, ligand recognition and regulation of leucine-aspartic acid (LD) motifs

    KAUST Repository

    Alam, Tanvir

    2014-05-29

    LD motifs (leucine-aspartic acidmotifs) are short helical protein-protein interaction motifs that have emerged as key players in connecting cell adhesion with cell motility and survival. LD motifs are required for embryogenesis, wound healing and the evolution of multicellularity. LD motifs also play roles in disease, such as in cancer metastasis or viral infection. First described in the paxillin family of scaffolding proteins, LD motifs and similar acidic LXXLL interaction motifs have been discovered in several other proteins, whereas 16 proteins have been reported to contain LDBDs (LD motif-binding domains). Collectively, structural and functional analyses have revealed a surprising multivalency in LD motif interactions and a wide diversity in LDBD architectures. In the present review, we summarize the molecular basis for function, regulation and selectivity of LD motif interactions that has emerged from more than a decade of research. This overview highlights the intricate multi-level regulation and the inherently noisy and heterogeneous nature of signalling through short protein-protein interaction motifs. © 2014 Biochemical Society.

  6. Synthesis and characterization of new optically active copoly(amid-imide)s based on N-phthalimido-L-aspartic acid and aromatic diamines

    Institute of Scientific and Technical Information of China (English)

    Khalil; Faghihi; Hamidreza; Alimohammadi

    2010-01-01

    In this article,six new optically active copoly(amide-imide)s(10a-f) were synthesized through the direct polycondensation reaction of N-phthalimido-L-aspartic acid(4) with 1,5-diamino naphthalene(8),3,4-diamino benzophenone(9) in the presence of therphthahc acid(7),fumaric acid(6) and adipic acid(5) as a second diacid in a medium consisting of N-methyl-2-pyrrolidone,triphenyl phosphite, calcium chloride and pyridine.The resulting copolymers were fully characterized by means of FT-IR spectroscopy,elementa...

  7. Regulatory structure of the biosynthetic pathway for the aspartate family of amino acids in Lemna paucicostata Hegelm. 6746, with special reference to the role of aspartokinase

    International Nuclear Information System (INIS)

    Comprehensive studies were made with Lemna paucicostate Hegelm. 6746 of the effects of combinations of lysine, methionine, and threonine on growth rates, soluble amino acid contents, aspartokinase activities, and fluxes of 4-carbon moieties from aspartate through the aspartokinase step into the amino acids of the aspartate family. These studies show that flux in vitro through the aspartokinase step is insensitive to inhibition by lysine or threonine, and confirm previous in vitro data in establishing that aspartokinase in vivo is present in two orders of magnitude excess of its requirements. No evidence of channeling of the products of the lysine- and threonine-sensitive aspartokinases was obtained, either form of the enzyme along being more than adequate for the combined in vivo flux through the aspartokinase step. The marked insensitivity of flux through the aspartokinase step to inhibition by lysine or threonine strongly suggests that inhibition of aspartokinase by these amino acids is not normally a major factor in regulation of entry of 4-carbon units into the aspartate family of amino acids. Direct measurement of fluxes of 4-carbon units demonstrated that: (a) Lysine strongly feedback regulates its own synthesis, probably at the step catalyzed by dihydrodipicolinate synthase. (b) Threonine alone does not regulate its own synthesis in vivo, thereby confirming previous studies of the metabolism of [14C]threonine and [14C]homoserine in Lemna

  8. Engineering Dehydrated Amino Acid Residues in the Antimicrobial Peptide Nisin

    NARCIS (Netherlands)

    Kuipers, Oscar P.; Rollema, Harry S.; Yap, Wyanda M.G.J.; Boot, Hein J.; Siezen, Roland J.; Vos, Willem M. de

    1992-01-01

    The small antimicrobial peptide nisin, produced by Lactococcus lactis, contains the uncommon amino acid residues dehydroalanine and dehydrobutyrine and five thio ether bridges. Since these structures are posttranslationally formed from Ser, Thr, and Cys residues, it is feasible to study their role i

  9. Molecular cloning and enzymological characterization of pyridoxal 5'-phosphate independent aspartate racemase from hyperthermophilic archaeon Thermococcus litoralis DSM 5473.

    Science.gov (United States)

    Washio, Tsubasa; Kato, Shiro; Oikawa, Tadao

    2016-09-01

    We succeeded in expressing the aspartate racemase homolog gene from Thermococcus litoralis DSM 5473 in Escherichia coli Rosetta (DE3) and found that the gene encodes aspartate racemase. The aspartate racemase gene consisted of 687 bp and encoded 228 amino acid residues. The purified enzyme showed aspartate racemase activity with a specific activity of 1590 U/mg. The enzyme was a homodimer with a molecular mass of 56 kDa and did not require pyridoxal 5'-phosphate as a coenzyme. The enzyme showed aspartate racemase activity even at 95 °C, and the activation energy of the enzyme was calculated to be 51.8 kJ/mol. The enzyme was highly thermostable, and approximately 50 % of its initial activity remained even after incubation at 90 °C for 11 h. The enzyme showed a maximum activity at a pH of 7.5 and was stable between pH 6.0 and 7.0. The enzyme acted on L-cysteic acid and L-cysteine sulfinic acid in addition to D- and L-aspartic acids, and was strongly inhibited by iodoacetic acid. The site-directed mutagenesis of the enzyme showed that the essential cysteine residues were conserved as Cys83 and Cys194. D-Forms of aspartic acid, serine, alanine, and valine were contained in T. litoralis DSM 5473 cells. PMID:27438592

  10. Fatty Acid Structure and Degradation Analysis in Fingerprint Residues

    Science.gov (United States)

    Pleik, Stefanie; Spengler, Bernhard; Schäfer, Thomas; Urbach, Dieter; Luhn, Steven; Kirsch, Dieter

    2016-09-01

    GC-MS investigations were carried out to elucidate the aging behavior of unsaturated fatty acids in fingerprint residues and to identify their degradation products in aged samples. For this purpose, a new sample preparation technique for fingerprint residues was developed that allows producing N-methyl- N-trimethylsilyl-trifluoroacetamide (MSTFA) derivatives of the analyzed unsaturated fatty acids and their degradation products. MSTFA derivatization catalyzed by iodotrimethylsilane enables the reliable identification of aldehydes and oxoacids as characteristic MSTFA derivatives in GCMS. The obtained results elucidate the degradation pathway of unsaturated fatty acids. Our study of aged fingerprint residues reveals that decanal is the main degradation product of the observed unsaturated fatty acids. Furthermore, oxoacids with different chain lengths are detected as specific degradation products of the unsaturated fatty acids. The detection of the degradation products and their chain length is a simple and effective method to determine the double bond position in unsaturated compounds. We can show that the hexadecenoic and octadecenoic acids found in fingerprint residues are not the pervasive fatty acids Δ9-hexadecenoic (palmitoleic acid) and Δ9-octadecenoic (oleic acid) acid but Δ6-hexadecenoic acid (sapienic acid) and Δ8-octadecenoic acid. The present study focuses on the structure identification of human sebum-specific unsaturated fatty acids in fingerprint residues based on the identification of their degradation products. These results are discussed for further investigations and method developments for age determination of fingerprints, which is still a tremendous challenge because of several factors affecting the aging behavior of individual compounds in fingerprints.

  11. Fatty Acid Structure and Degradation Analysis in Fingerprint Residues.

    Science.gov (United States)

    Pleik, Stefanie; Spengler, Bernhard; Schäfer, Thomas; Urbach, Dieter; Luhn, Steven; Kirsch, Dieter

    2016-09-01

    GC-MS investigations were carried out to elucidate the aging behavior of unsaturated fatty acids in fingerprint residues and to identify their degradation products in aged samples. For this purpose, a new sample preparation technique for fingerprint residues was developed that allows producing N-methyl-N-trimethylsilyl-trifluoroacetamide (MSTFA) derivatives of the analyzed unsaturated fatty acids and their degradation products. MSTFA derivatization catalyzed by iodotrimethylsilane enables the reliable identification of aldehydes and oxoacids as characteristic MSTFA derivatives in GCMS. The obtained results elucidate the degradation pathway of unsaturated fatty acids. Our study of aged fingerprint residues reveals that decanal is the main degradation product of the observed unsaturated fatty acids. Furthermore, oxoacids with different chain lengths are detected as specific degradation products of the unsaturated fatty acids. The detection of the degradation products and their chain length is a simple and effective method to determine the double bond position in unsaturated compounds. We can show that the hexadecenoic and octadecenoic acids found in fingerprint residues are not the pervasive fatty acids Δ9-hexadecenoic (palmitoleic acid) and Δ9-octadecenoic (oleic acid) acid but Δ6-hexadecenoic acid (sapienic acid) and Δ8-octadecenoic acid. The present study focuses on the structure identification of human sebum-specific unsaturated fatty acids in fingerprint residues based on the identification of their degradation products. These results are discussed for further investigations and method developments for age determination of fingerprints, which is still a tremendous challenge because of several factors affecting the aging behavior of individual compounds in fingerprints. Graphical Abstract ᅟ. PMID:27324649

  12. Nanofiltration of L-phenylalanine and L-aspartic acid aqueous solution and its process simulation%苯丙氨酸和天冬氨酸水溶液的纳滤分离及其过程模拟

    Institute of Scientific and Technical Information of China (English)

    王晓琳; 营爱玲

    2001-01-01

    选择苯丙氨酸和天冬氨酸水溶液进行了纳滤分离过程研究,讨论了不同pH下氨基酸的透过特性,并就该体系的浓缩分离进行了模拟计算.%The permeation experiments of aqueous solution of amino acids (L-phenylalanine and L-Aspartic acid) were carried out with nanofiltration membranes. The rejections of phenylalanine and aspartic acid are about 0 and 90%, respectively. The results show that the amino acids having large differences of isoelectric points (pI) can be separated satisfactorily by adjusting the value of pH. Then the concentration and separation process of phenylalanine and aspartic acid solution was simulated. A batchwise concentration and diafiltration system was designed. The results show that it is feasible to separate phenylalanine and aspartic acid in viewpoint of technology.

  13. Role of enthalpy-entropy compensation interactions in determining the conformational propensities of amino acid residues in unfolded peptides.

    Science.gov (United States)

    Toal, Siobhan E; Verbaro, Daniel J; Schweitzer-Stenner, Reinhard

    2014-02-01

    The driving forces governing the unique and restricted conformational preferences of amino acid residues in the unfolded state are still not well understood. In this study, we experimentally determine the individual thermodynamic components underlying intrinsic conformational propensities of these residues. Thermodynamic analysis of ultraviolet-circular dichroism (UV-CD) and (1)H NMR data for a series of glycine capped amino acid residues (i.e., G-x-G peptides) reveals the existence of a nearly exact enthalpy-entropy compensation for the polyproline II-β strand equilibrium for all investigated residues. The respective ΔHβ, ΔSβ values exhibit a nearly perfect linear relationship with an apparent compensation temperature of 295 ± 2 K. Moreover, we identified iso-equilibrium points for two subsets of residues at 297 and 305 K. Thus, our data suggest that within this temperature regime, which is only slightly below physiological temperatures, the conformational ensembles of amino acid residues in the unfolded state differ solely with respect to their capability to adopt turn-like conformations. Such iso-equilibria are rarely observed, and their existence herein indicates a common physical origin behind conformational preferences, which we are able to assign to side-chain dependent backbone solvation. Conformational effects such as differences between the number of sterically allowed side chain rotamers can contribute to enthalpy and entropy but not to the Gibbs energy associated with conformational preferences. Interestingly, we found that alanine, aspartic acid, and threonine are the only residues which do not share these iso-equilbiria. The enthalpy-entropy compensation discovered as well as the iso-equilbrium and thermodynamics obtained for each amino acid residue provide a new and informative way of identifying the determinants of amino acid propensities in unfolded and disordered states.

  14. Estimation of free energy barriers in the cytoplasmic and mitochondrial aspartate aminotransferase reactions probed by hydrogen-exchange kinetics of C alpha-labeled amino acids with solvent

    Energy Technology Data Exchange (ETDEWEB)

    Julin, D.A.; Wiesinger, H.; Toney, M.D.; Kirsch, J.F. (Univ. of California, Berkeley (USA))

    1989-05-02

    The existence of the postulated quinonoid intermediate in the cytoplasmic aspartate amino-transferase catalyzed transamination of aspartate to oxaloacetate was probed by determining the extent of transfer of tritium from the C alpha position of tritiated L-aspartate to pyridoxamine 5'-phosphate in single turnover experiments in which washout from the back-reaction was obviated by product trapping. The maximum amount of transferred tritium observed was 0.7%, consistent either with a mechanism in which a fraction of the net transamination reaction proceeds through a quinonoid intermediate or with a mechanism in which this intermediate is formed off the main reaction pathway. It is shown that transfer of labeled hydrogen from the amino acid to cofactor cannot be used to differentiate a stepwise from a concerted transamination mechanism. The amount of tritium transferred is a function of the rate constant for torsional equilibration about the epsilon-amino group of Lys-258, the presumptive abstractor of the C alpha proton; the relative rate constants for hydrogen exchange with solvent versus cofactor protonation; and the tritium isotope effect on this ratio. The free energy barriers facing the covalent intermediate between aldimine and keto acid product (i.e., ketimine and possibly quinonoid) were evaluated relatively by comparing the rates of C alpha-hydrogen exchange in starting amino acid with the rates of keto acid formation. The value of theta (= kexge/kprod) was found to be 2.6 for the reaction of cytoplasmic isozyme with aspartate and ca. 0.5 for that of the mitochondrial form with glutamate.

  15. Inhibition mechanism analysis & research of the poly aspartic acid corrosion inhibitor%聚天冬氨酸缓蚀剂缓蚀机理分析研究

    Institute of Scientific and Technical Information of China (English)

    王娴

    2012-01-01

    文中介绍了聚天冬氨酸缓蚀剂缓蚀机理,并对聚天冬氨酸缓蚀剂机理的研究现状以及发展趋势进行了综述。%It was introduced inhibition mechanism of the poly aspartic acid corrosion inhibitor. Mean- while, it was summarizeed the research progress of the inhibition meehanismf the poly aspartic acid cor- rosion inhibitor and the development trend of the poly aspartic acid corrosion inhibitor in this article.

  16. Protection of Hydroxyl Groups as a Trimethylsilyl Ether by1,1,1,3,3,3-Hexamethyldisilazane Promoted by Aspartic Acid as an Efficient Organocatalyst%Protection of Hydroxyl Groups as a Trimethylsilyl Ether by 1,1,1,3,3,3-Hexamethyldisilazane Promoted by Aspartic Acid as an Efficient Organocatalyst

    Institute of Scientific and Technical Information of China (English)

    Arash GHORBANI-CHOGHAMARANI; Masoomeh NOROUZI

    2011-01-01

    A wide variety of alcohols and phenols were protected as trimethylsilyl ethers using 1,1,1,3,3,3-hexamethyl disilazane catalyzed by aspartic acid as a non-toxic, metal-free, and green organocatalyst at room temperature in acetonitrile under mild and heterogeneous conditions. The procedure is operationally simple and the silylated product was obtained in high yield and purity.

  17. The effect of preirradiation application of aspartic acid salts on hemopoietic recovery in X-irradiated mice

    International Nuclear Information System (INIS)

    The possibility of radioprotective action of K and Mg aspartate administered in tap water for ten days prior to X-irradiation was investigated in male mice of the strain C 57 Bl/10. In normal animals, thymus weight was found to be increased by 10-day treatment with K and Mg aspartate. The postirradiation regeneration of spleen weight and incorporation of radioactive iron into the spleen and femoral marrow following sublethal irradiation was favorably modified by the treatment used. Pretreatment of mice with K and Mg aspartate delays the onset of early deaths at irradiation with an absolutely lethal X-ray exposure and raises the percentage of surviving animals after nearly lethal exposures. (orig.)

  18. Mutations that cause threonine sensitivity identify catalytic and regulatory regions of the aspartate kinase of Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Arévalo-Rodríguez, M; Calderón, I L; Holmberg, S

    1999-01-01

    . The corresponding amino acid substitutions, K26I and G25D, affect residues located in the vicinity of a highly conserved lysine-phenylalanine-glycine-glycine (KFGG) stretch present in the N-terminal part of the aspartate kinase, to which no function has so far been assigned. We suggest that this region is involved...... inhibited by threonine than the wild-type enzyme. The predicted amino acid substitution in this mutant, A406T, is located in a region associated with the modulation of the enzymatic activity. The other two mutants carry an aspartate kinase with reduced affinity for its substrates, aspartate and ATP...

  19. Synthesis of aqueous suspensions of magnetic nanoparticles with the co-precipitation of iron ions in the presence of aspartic acid

    Science.gov (United States)

    Pušnik, Klementina; Goršak, Tanja; Drofenik, Miha; Makovec, Darko

    2016-09-01

    There is increasing demand for the production of large quantities of aqueous suspensions of magnetic iron-oxide nanoparticles. Amino acids are one possible type of inexpensive, nontoxic, and biocompatible molecules that can be used as the surfactants for the preparation of stable suspensions. This preparation can be conducted in a simple, one-step process based on the co-precipitation of Fe3+/Fe2+ ions in the presence of the amino acid. However, the presence of this amino acid changes the mechanism of the magnetic nanoparticles' formation. In this investigation we analyzed the influence of aspartic amino acid (Asp) on the formation of magnetic iron-oxide nanoparticles during the co-precipitation. The process of the nanoparticles' formation was followed using a combination of TEM, x-ray diffractometry, magnetic measurements, in-situ FT-IR spectroscopy, and chemical analysis, and compared with the formation of nanoparticles without the Asp. The Asp forms a coordination complex with the Fe3+ ions, which impedes the formation of the intermediate iron oxyhydroxide phase and suppresses the growth of the final magnetic iron-oxide nanoparticles. Slower reaction kinetics can lead to the formation of nonmagnetic secondary phases. The aspartic-acid-absorbed nanoparticles can be dispersed to form relatively concentrated aqueous suspensions displaying a good colloidal stability at an increased pH.

  20. Detection of Serine Octamer by Desorption Electrospray Ionization Mass Spectrometry in Resultant Mixture of Aspartic Acid Exposed to Sunshine Under Natural Conditions

    Institute of Scientific and Technical Information of China (English)

    CHEN Huan-wen; LI Ming; JIN Wei; JIN Qin-han; ZHENG Jian

    2007-01-01

    Serine, one of the nonessential amino acids, is of principal interest because of its capability to form magic-number ionic clusters, which provide a remarkable preference for homochirality. With L-aspartic acid as the precursor,this study provides experimental evidence for serine formation in weak acidified aqueous solutions in the presence of iron, with exposure to sunlight, which simulates the natural conditions of the prebiotic aqueous environment. The resultant mixture is directly analyzed via desorption electrospray ionization mass spectrometry( DESI-MS), without any sample preseparation. The serine monomer is successfully detected as protonated molecules, giving a peak at m/z 106, which is confirmed by the MS/MS fragments. Protonated serine octamer(m/z 841) is also observed with significant abundance in the MS spectra and is confirmed by the MS/MS data, which shows the formation of the serine octamer by a synthesized serine in the resultant mixture. It is also found that the serine octamer yielded equivalent abundance in the DESI mass spectra in a wide pH range(pH=1-5), and that existence of ferrous salt and sunshine are essential for the conversion of aspartic acid to serine in the acidic water solution.

  1. Aspartate aminotransferase – key enzyme in the human systemic metabolism

    Directory of Open Access Journals (Sweden)

    Dagmara Otto-Ślusarczyk

    2016-03-01

    Full Text Available Aspartate aminotransferase is an organ - nonspecific enzyme located in many tissues of the human body where it catalyzes reversible reaction of transamination. There are two aspartate aminotransferase isoforms - cytoplasmic (AST1 and mitochondrial (AST2, that usually occur together and interact with each other metabolically. Both isoforms are homodimers containing highly conservative regions responsible for catalytic properties of enzyme. The common feature of all aspartate aminotransfeses is Lys – 259 residue covalent binding with prosthetic group - pyridoxal phosphate. The differences in the primary structure of AST isoforms determine their physico-chemical, kinetic and immunological properties. Because of the low concentration of L-aspartate (L-Asp in the blood, AST is the only enzyme, which supply of this amino acid as a substrate for many metabolic processes, such as urea cycle or purine and pyrimidine nucleotides in the liver, synthesis of L-arginine in the kidney and purine nucleotide cycle in the brain and the skeletal muscle. AST is also involved in D-aspartate production that regulates the metabolic activity at the auto-, para- and endocrine level. Aspartate aminotransferase is a part of the malate-aspartate shuttle in the myocardium, is involved in gluconeogenesis in the liver and kidney, glyceroneogenesis in the adipose tissue, and synthesis of neurotransmitters and neuro-glial pathway in the brain. Recently, the significant role of AST in glutaminolysis - normal metabolic pathway in tumor cells, was demonstrated. The article is devoted the role of AST, known primarily as a diagnostic liver enzyme, in metabolism of various human tissues and organs.

  2. Amphoteric surfactants containing ?-hydroxy ester group and an amino acid residue

    Directory of Open Access Journals (Sweden)

    Eissa, A. M. F.

    2006-09-01

    Full Text Available A series of amphoteric surfactants containing α-hydroxy ester group and an amino acid residue were prepared with the addition of epoxy derivatives (which were prepared from epoxidation of alkyl methacrylate to different types of amino acids (glycine, alanine, valine, isoleucine, phenylalanine, tyrosine, serine, threonine, aspartic and anthranilic acid.The structures of the prepared compounds were confirmed by infrared spectra, proton magnetic resonance spectra, Mass spectra and elementary analysis. Surface tension, Kraft point, foaming power, critical micelle concentration emulsion and Ca++ stabilities were determined. Antimicrobial activity and biodegradability were also screened.Se prepararon una serie de tensioactivos anfóteros conteniendo un grupo alfa hidroxi éster y un residuo de aminoácido por adición de derivados epoxy (obtenidos mediante epoxidación de metacrilato de alquilo a diferentes tipos de aminoácidos (glicina, alanina, valina, isoleucina, fenilalanina, tirosina, serina, treonina y ácidos aspártico y antranílico. Las estructuras de los compuestos preparados se confirmaron por los espectros de infrarrojo, de masa, resonancia magnética nuclear de protones y análisis elemental. Se determinaron la tensión superficial, el punto de Kraft, el poder espumante, la concentración micelar crítica en emulsión y las estabilidades de Ca++. También se estudiaron la actividad antimicrobiana y la biodegradabilidad.

  3. Topological features of proteins from amino acid residue networks

    CERN Document Server

    Alves, N A; Alves, Nelson Augusto; Martinez, Alexandre Souto

    2006-01-01

    Topological properties of native folds are obtained from statistical analysis of 160 low homology proteins covering the four structural classes. This is done analysing one, two and three-vertex joint distribution of quantities related to the corresponding network of amino acid residues. Emphasis on the amino acid residue hydrophobicity leads to the definition of their center of mass as vertices in this contact network model with interactions represented by edges. The network analysis helps us to interpret experimental results such as hydrophobic scales and fraction of buried accessible surface area in terms of the network connectivity. To explore the vertex type dependent correlations, we build a network of hydrophobic and polar vertices. This procedure presents the wiring diagram of the topological structure of globular proteins leading to the following attachment probabilities between hydrophobic-hydrophobic 0.424(5), hydrophobic-polar 0.419(2) and polar-polar 0.157(3) residues.

  4. Electrocatalytic oxidation and determination of dopamine at a carbon ionic liquid electrode modified with nafion-L-aspartic acid composite film

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The electrocatalytic oxidation of dopamine(DA)was studied by electrochemical approaches at a carbon ionic liquid electrode(CILE)modified with the composite film of nafion and L-aspartic acid(NL-CILE).The CILE was fabricated by replacing non-conductive organic binders with a room-temperature hydrophobic ionic liquid,1-butyl-3-methyl-imidazolium hexafluorophosphate.The composite film of NL was used as matrix to adsorb DA and catalyze the oxidation of DA in phosphate buffer solution(PBS).The electrochemical re...

  5. The glycine transporter GlyT1 controls N-methyl-D-aspartic acid receptor coagonist occupancy in the mouse retina

    OpenAIRE

    Brian T Reed; Sullivan, Steven J.; Tsai, Guochuan; Coyle, Joseph T.; Esguerra, Manuel; Miller, Robert F.

    2009-01-01

    We examined the role of GlyT1, the high-affinity glycine transporter, in the mouse retina with an emphasis on the role of glycine as a coagonist of N-methyl-D-aspartic acid (NMDA) receptors. We pursued this objective by studying heterozygote mice deficient in the GlyT1 transporter (GlyT1−/+) and compared those results with wild-type (WT) littermate controls (GlyT1+/+). Capillary electrophoresis was used to separate and quantitatively measure glycine release from isolated retina preparations; ...

  6. Synthesis and Properties of pH-, Thermo-, and Salt-Sensitive Modified Poly(aspartic acid/Poly(vinyl alcohol IPN Hydrogel and Its Drug Controlled Release

    Directory of Open Access Journals (Sweden)

    Jingqiong Lu

    2015-01-01

    Full Text Available Modified poly(aspartic acid/poly(vinyl alcohol interpenetrating polymer network (KPAsp/PVA IPN hydrogel for drug controlled release was synthesized by a simple one-step method in aqueous system using poly(aspartic acid grafting 3-aminopropyltriethoxysilane (KH-550 and poly(vinyl alcohol (PVA as materials. The hydrogel surface morphology and composition were characterized by Fourier transform infrared spectroscopy (FTIR and scanning electron microscopy (SEM. The thermal stability was analyzed by thermogravimetric analysis (TGA. The swelling properties and pH, temperature, and salt sensitivities of KPAsp, KPAsp/PVA semi-interpenetrating polymer network (semi-IPN, and KPAsp/PVA IPN hydrogels were also investigated. All of the three hydrogels showed ampholytic pH-responsive properties, and swelling behavior was also extremely sensitive to the temperature, ionic strength, and cationic species. Finally, the drug controlled release properties of the three hydrogels were evaluated and results indicated that three hydrogels could control drug release by external surroundings stimuli. The drug controlled release properties of KPAsp/PVA IPN hydrogel are the most outstanding, and the correlative measured release profiles of salicylic acid at 37°C were 32.6 wt% at pH = 1.2 (simulated gastric fluid and 62.5 wt% at pH = 7.4 (simulated intestinal fluid, respectively. These results indicated that KPAsp/PVA IPN hydrogels are a promising carrier system for controlled drug delivery.

  7. Synthesis and Properties of pH-, Thermo-, and Salt-Sensitive Modified Poly(aspartic acid)/Poly(vinyl alcohol) IPN Hydrogel and Its Drug Controlled Release.

    Science.gov (United States)

    Lu, Jingqiong; Li, Yinhui; Hu, Deng; Chen, Xiaoling; Liu, Yongmei; Wang, Liping; Zhao, Yansheng

    2015-01-01

    Modified poly(aspartic acid)/poly(vinyl alcohol) interpenetrating polymer network (KPAsp/PVA IPN) hydrogel for drug controlled release was synthesized by a simple one-step method in aqueous system using poly(aspartic acid) grafting 3-aminopropyltriethoxysilane (KH-550) and poly(vinyl alcohol) (PVA) as materials. The hydrogel surface morphology and composition were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The thermal stability was analyzed by thermogravimetric analysis (TGA). The swelling properties and pH, temperature, and salt sensitivities of KPAsp, KPAsp/PVA semi-interpenetrating polymer network (semi-IPN), and KPAsp/PVA IPN hydrogels were also investigated. All of the three hydrogels showed ampholytic pH-responsive properties, and swelling behavior was also extremely sensitive to the temperature, ionic strength, and cationic species. Finally, the drug controlled release properties of the three hydrogels were evaluated and results indicated that three hydrogels could control drug release by external surroundings stimuli. The drug controlled release properties of KPAsp/PVA IPN hydrogel are the most outstanding, and the correlative measured release profiles of salicylic acid at 37°C were 32.6 wt% at pH = 1.2 (simulated gastric fluid) and 62.5 wt% at pH = 7.4 (simulated intestinal fluid), respectively. These results indicated that KPAsp/PVA IPN hydrogels are a promising carrier system for controlled drug delivery. PMID:26351630

  8. Composite poly-L-lactic acid/poly-(α,β)-DL-aspartic acid/collagen nanofibrous scaffolds for dermal tissue regeneration

    International Nuclear Information System (INIS)

    Tissue engineering scaffolds for skin tissue regeneration is an ever expounding area of research, as the products that meet the necessary requirements are far and elite. The nanofibrous poly-L-lactic acid/poly-(α,β)-DL-aspartic acid/Collagen (PLLA/PAA/Col I and III) scaffolds were fabricated by electrospinning and characterized by SEM, contact angle and FTIR analysis for skin tissue regeneration. The cell-scaffold interactions were analyzed by cell proliferation and their morphology observed in SEM. The results showed that the cell proliferation was significantly increased (p ≤ 0.05) in PLLA/PAA/Col I and III scaffolds compared to PLLA and PLLA/PAA nanofibrous scaffolds. The abundance and accessibility of adipose derived stem cells (ADSCs) may prove to be novel cell therapeutics for dermal tissue regeneration. The differentiation of ADSCs was confirmed using collagen expression and their morphology by CMFDA dye extrusion technique. The current study focuses on the application of PLLA/PAA/Col I and III nanofibrous scaffolds for skin tissue engineering and their potential use as substrate for the culture and differentiation of ADSCs. The objective for inclusion of a novel cell binding moiety like PAA was to replace damaged extracellular matrix and to guide new cells directly into the wound bed with enhanced proliferation and overall organization. This combinatorial epitome of PLLA/PAA/Col I and III nanofibrous scaffold with stem cell therapy to induce the necessary paracrine signalling effect would favour faster regeneration of the damaged skin tissues. - Highlights: ► Differentiation of adipose derived stem cells in the presence of bFGF for wound healing ► Introduction of PAA as ECM mimetic cell binding moiety ► Combination of PLLA/PAA/Col I and III nanofibers and stem cell therapy for skin regeneration.

  9. Composite poly-L-lactic acid/poly-({alpha},{beta})-DL-aspartic acid/collagen nanofibrous scaffolds for dermal tissue regeneration

    Energy Technology Data Exchange (ETDEWEB)

    Ravichandran, Rajeswari [Healthcare and Energy Materials Laboratory, Nanoscience and Nanotechnology Initiative, Faculty of Engineering, National University of Singapore, 117576 (Singapore); Department of Mechanical Engineering, National University of Singapore, 117576 (Singapore); Venugopal, Jayarama Reddy, E-mail: nnijrv@nus.edu.sg [Healthcare and Energy Materials Laboratory, Nanoscience and Nanotechnology Initiative, Faculty of Engineering, National University of Singapore, 117576 (Singapore); Sundarrajan, Subramanian [Healthcare and Energy Materials Laboratory, Nanoscience and Nanotechnology Initiative, Faculty of Engineering, National University of Singapore, 117576 (Singapore); Department of Mechanical Engineering, National University of Singapore, 117576 (Singapore); Mukherjee, Shayanti [Healthcare and Energy Materials Laboratory, Nanoscience and Nanotechnology Initiative, Faculty of Engineering, National University of Singapore, 117576 (Singapore); Sridhar, Radhakrishnan [Healthcare and Energy Materials Laboratory, Nanoscience and Nanotechnology Initiative, Faculty of Engineering, National University of Singapore, 117576 (Singapore); Department of Mechanical Engineering, National University of Singapore, 117576 (Singapore); Ramakrishna, Seeram, E-mail: seeram@nus.edu.sg [Healthcare and Energy Materials Laboratory, Nanoscience and Nanotechnology Initiative, Faculty of Engineering, National University of Singapore, 117576 (Singapore); Department of Mechanical Engineering, National University of Singapore, 117576 (Singapore)

    2012-08-01

    Tissue engineering scaffolds for skin tissue regeneration is an ever expounding area of research, as the products that meet the necessary requirements are far and elite. The nanofibrous poly-L-lactic acid/poly-({alpha},{beta})-DL-aspartic acid/Collagen (PLLA/PAA/Col I and III) scaffolds were fabricated by electrospinning and characterized by SEM, contact angle and FTIR analysis for skin tissue regeneration. The cell-scaffold interactions were analyzed by cell proliferation and their morphology observed in SEM. The results showed that the cell proliferation was significantly increased (p {<=} 0.05) in PLLA/PAA/Col I and III scaffolds compared to PLLA and PLLA/PAA nanofibrous scaffolds. The abundance and accessibility of adipose derived stem cells (ADSCs) may prove to be novel cell therapeutics for dermal tissue regeneration. The differentiation of ADSCs was confirmed using collagen expression and their morphology by CMFDA dye extrusion technique. The current study focuses on the application of PLLA/PAA/Col I and III nanofibrous scaffolds for skin tissue engineering and their potential use as substrate for the culture and differentiation of ADSCs. The objective for inclusion of a novel cell binding moiety like PAA was to replace damaged extracellular matrix and to guide new cells directly into the wound bed with enhanced proliferation and overall organization. This combinatorial epitome of PLLA/PAA/Col I and III nanofibrous scaffold with stem cell therapy to induce the necessary paracrine signalling effect would favour faster regeneration of the damaged skin tissues. - Highlights: Black-Right-Pointing-Pointer Differentiation of adipose derived stem cells in the presence of bFGF for wound healing Black-Right-Pointing-Pointer Introduction of PAA as ECM mimetic cell binding moiety Black-Right-Pointing-Pointer Combination of PLLA/PAA/Col I and III nanofibers and stem cell therapy for skin regeneration.

  10. Amendment of Acid Soils with Crop Residues and Biochars

    Institute of Scientific and Technical Information of China (English)

    YUAN Jin-Hua; XU Ren-Kou; WANG Ning; LI Jiu-Yu

    2011-01-01

    The liming potential of some crop residues and their biochars on an acid Ultisol was investigated using incubation experiments. Rice hulls showed greater liming potential than rice hull biochar, while soybean and pea straws had less liming potential than their biochars. Due to their higher alkalinity, biochars from legume materials increased soil pH much compared to biochars from non-legume materials. The alkalinity of biochars was a key factor affecting their liming potential,and the greater alkalinity of biochars led to greater reductions in soil acidity. The incorporation of biochars decreased soil exchangeable acidity and increased soil exchangeable base cations and base saturation, thus improving soil fertility.

  11. The role for an invariant aspartic acid in hypoxanthine phosphoribosyltransferases is examined using saturation mutagenesis, functional analysis, and X-ray crystallography.

    Science.gov (United States)

    Canyuk, B; Focia, P J; Eakin, A E

    2001-03-01

    The role of an invariant aspartic acid (Asp137) in hypoxanthine phosphoribosyltransferases (HPRTs) was examined by site-directed and saturation mutagenesis, functional analysis, and X-ray crystallography using the HPRT from Trypanosoma cruzi. Alanine substitution (D137A) resulted in a 30-fold decrease of k(cat), suggesting that Asp137 participates in catalysis. Saturation mutagenesis was used to generate a library of mutant HPRTs with random substitutions at position 137, and active enzymes were identified by complementation of a bacterial purine auxotroph. Functional analyses of the mutants, including determination of steady-state kinetic parameters and pH-rate dependence, indicate that glutamic acid or glutamine can replace the wild-type aspartate. However, the catalytic efficiency and pH-rate profile for the structural isosteric mutant, D137N, were similar to the D137A mutant. Crystal structures of four of the mutant enzymes were determined in ternary complex with substrate ligands. Structures of the D137E and D137Q mutants reveal potential hydrogen bonds, utilizing several bound water molecules in addition to protein atoms, that position these side chains within hydrogen bond distance of the bound purine analogue, similar in position to the aspartate in the wild-type structure. The crystal structure of the D137N mutant demonstrates that the Asn137 side chain does not form interactions with the purine substrate but instead forms novel interactions that cause the side chain to adopt a nonfunctional rotamer. The results from these structural and functional analyses demonstrate that HPRTs do not require a general base at position 137 for catalysis. Instead, hydrogen bonding sufficiently stabilizes the developing partial positive charge at the N7-atom of the purine substrate in the transition-state to promote catalysis.

  12. Synthesis and characterization of aspartic acid-capped CdS/ZnS quantum dots in reverse micelles and its application to Hg(II) determination

    Energy Technology Data Exchange (ETDEWEB)

    Hosseini, Mohammad Saeid, E-mail: mshosseini1336@yahoo.com; Kamali, Mohsen

    2015-11-15

    In this work, CdS/ZnS quantum dots (QDs) coated with aspartic acid (AsA) were synthesized in reverse micelles. The synthesized QDs were characterized by XRD, TEM, IR and photoluminescence (PL) spectroscopy. It was found that the intensity of CdS/ZnS QDs coated with AsA is much greater than CdS, and CdS/ZnS QDs. The interaction of some heavy metal ions with CdS/ZnS/AsA QDs was investigated at different buffering pH media. Based on the PL quenching of the QDs in the presence of each one of the metal ions, the feasibility of their determinations was examined according to the Stern–Volmer equation. The investigations showed that Hg(II) ions can be easily determined in contaminated atmospheric environments with the detection limit of 0.05 mg m{sup −3}. The results were satisfactorily confirmed by cold vapor atomic absorption spectrometric method. - Highlights: • A new CdS/ZnS quantum dot capped with aspartic acid (DDBA) was prepared. • The prepared QDs benefit from a favorable fluorescence. • Interaction of some metal ions with the QDs was examined according to the Stern–Volmer equation. • The determination of Hg(II) is feasible in the present of many co-existence metal ions. • The method benefits from a high-speed and considerable simplicity for Hg(II) determination.

  13. Corticosterone, cortisol, triglycerides, aspartate aminotransferase and uric acid plasma concentrations during foie gras production in male mule ducks (Anas platyrhynchos × Cairina moschata).

    Science.gov (United States)

    Flament, A; Delleur, V; Poulipoulis, A; Marlier, D

    2012-01-01

    1. Corticosterone, cortisol, triglycerides, aspartate aminotransferase (AST) and uric acid (UA) plasma concentration were measured at 8 (7 days after group housing), 12 (after 7 days of force feeding) and 13 weeks of age (at slaughter after 12 days of force feeding), and 45 min after an adrenocorticotrophic hormone (ACTH) stimulation test at 8 weeks of age in 12 male mule ducks in an on-farm experiment. 2. No significant increase of corticosterone was found during the force-feeding period compared with the concentration after housing. 3. Comparison of corticosterone and cortisol values indicates that cortisol can be considered as a reliable acute stress indicator in future routine examinations. 4. Plasma concentrations of triglycerides and aspartate aminotransferase increased progressively from pre-force feeding period to slaughtering. 5. Plasma concentrations of uric acid increased from the start at 8 weeks of age to the mid-force feeding period but no difference was noticed between the mid-force feeding period and slaughtering. 6. It is concluded that acute stress induced by force-feeding is similar at the beginning and end of the commercial production of foie gras.

  14. Synthesis and characterization of aspartic acid-capped CdS/ZnS quantum dots in reverse micelles and its application to Hg(II) determination

    International Nuclear Information System (INIS)

    In this work, CdS/ZnS quantum dots (QDs) coated with aspartic acid (AsA) were synthesized in reverse micelles. The synthesized QDs were characterized by XRD, TEM, IR and photoluminescence (PL) spectroscopy. It was found that the intensity of CdS/ZnS QDs coated with AsA is much greater than CdS, and CdS/ZnS QDs. The interaction of some heavy metal ions with CdS/ZnS/AsA QDs was investigated at different buffering pH media. Based on the PL quenching of the QDs in the presence of each one of the metal ions, the feasibility of their determinations was examined according to the Stern–Volmer equation. The investigations showed that Hg(II) ions can be easily determined in contaminated atmospheric environments with the detection limit of 0.05 mg m−3. The results were satisfactorily confirmed by cold vapor atomic absorption spectrometric method. - Highlights: • A new CdS/ZnS quantum dot capped with aspartic acid (DDBA) was prepared. • The prepared QDs benefit from a favorable fluorescence. • Interaction of some metal ions with the QDs was examined according to the Stern–Volmer equation. • The determination of Hg(II) is feasible in the present of many co-existence metal ions. • The method benefits from a high-speed and considerable simplicity for Hg(II) determination

  15. 聚天冬氨酸阻垢剂的制备及性能评价%Preparation and Performance Evaluation of Poly-aspartic Acid Scale Inhibitor

    Institute of Scientific and Technical Information of China (English)

    杨红丽; 姬彩云

    2015-01-01

    Poly-aspartic acid has good scale inhibition effect. Using maleic anhydride and ammonium chloride, poly-aspartic acid was prepared by hot-polymerization. And the optimum reaction conditions were obtained by or-thogonal experiment as follows:molar ratio of maleic anhydride/ammonium chloride was 1∶1. 2,reaction teampra-ture was 140℃,and reaction time was 5h.%聚天冬氨酸具有较好的阻垢效果。采用热引发聚合,以马来酸酐、氯化铵为原料,制备了绿色阻垢剂聚天冬氨酸,通过正交实验确定了最佳合成条件,并对其进行了性能评价。最佳合成条件为:马来酸酐和氯化铵的摩尔比为1∶1.2,反应温度为140℃,反应时间为5 h。

  16. The role of a conserved acidic residue in calcium-dependent protein folding for a low density lipoprotein (LDL)-A module: implications in structure and function for the LDL receptor superfamily.

    Science.gov (United States)

    Guo, Ying; Yu, Xuemei; Rihani, Kayla; Wang, Qing-Yin; Rong, Lijun

    2004-04-16

    One common feature of the more than 1,000 complement-type repeats (or low density lipoprotein (LDL)-A modules) found in LDL receptor and the other members of the LDL receptor superfamily is a cluster of five highly conserved acidic residues in the C-terminal region, DXXXDXXDXXDE. However, the role of the third conserved aspartate of these LDL-A modules in protein folding and ligand recognition has not been elucidated. In this report, using a model LDL-A module and several experimental approaches, we demonstrate that this acidic residue, like the other four conserved acidic residues, is involved in calcium-dependent protein folding. These results suggest an alternative calcium coordination conformation for the LDL-A modules. The proposed model provides a plausible explanation for the conservation of this acidic residue among the LDL-A modules. Furthermore, the model can explain why mutations of this residue in human LDL receptor cause familial hypercholesterolemia. PMID:14749324

  17. 苯丙氨酸和天冬氨酸水溶液的纳滤分离过程研究%The Nanofiltration Process of Aqueous Solution of Phenylalanine and Aspartic Acid

    Institute of Scientific and Technical Information of China (English)

    营爱玲; 王晓琳

    2001-01-01

    The permeation experiments on the aqueous solution of phenylalanine and aspartic acid were carried out with nanofiltration membranes. Results show that amino acids with different isoelectric points (pI) can be separated satisfactorily by adjusting the pH values. The concentration and separation process of phenylalanine and aspartic acid solution was also simulated.%选择L-苯丙氨酸和L-天冬氨酸水溶液进行了纳滤分离过程研究,讨论了不同pH下氨基酸的透过特性,并进行了模拟计算.

  18. Effect of propofol on the reactivity of acetylcholinesterase, N-methyl-D-aspartate receptors, and gamma-aminobutyric acid receptors in the hippocampus of aged rats after chronic cerebral ischemia

    Institute of Scientific and Technical Information of China (English)

    Gang Chen; Jiangbei Cao; Weidong Mi

    2011-01-01

    We induced ischemic brain injury in aging rats to examine the effects of varying doses of propofol on hippocampal activities of acetylcholinesterase, N-methyl-D-aspartate receptors, and γ-aminobutyric acid receptors. Propofol exhibited no obvious impact on acetylcholinesterase activity, but directly activated the γ-aminobutyric acid receptor. The neuroprotective function of propofol on the hippocampus of aging rats following cerebral ischemic injury may be related to altered activities of γ-aminobutyric acid receptors and N-methyl-D-aspartate receptors.

  19. Effect of aspartame and protein, administered in phenylalanine-equivalent doses, on plasma neutral amino acids, aspartate, insulin and glucose in man.

    Science.gov (United States)

    Møller, S E

    1991-05-01

    Six human males each received 0.56 g phenylalanine (Phe) in the form of 1.0 g aspartame or 12.2 g bovine albumin in 200 ml water or water alone. Venous blood samples collected before consumption and during the following 4 hr were assayed for plasma levels of large, neutral amino acids (LNAA), aspartate, insulin and glucose. The area under the curve for plasma Phe was 40% greater, although not significant, after aspartame compared with albumin intake. The indicated increased clearance rate of plasma Phe after albumin may be caused by the significant increase of insulin, on which aspartame had no effect. There was a significant main effect of aspartame for plasma tyrosine but not for tryptophan, valine, isoleucine or leucine. Plasma aspartate was significantly increased at 0.25 hr after the aspartame intake. The percentage Phe/LNAA decreased slightly in response to albumin but increased 55% after aspartame and remained significantly increased for 2 hr. Tyrosine/LNAA increased and tryptophan/LNAA decreased modestly after aspartame intake. The study showed that the intake of aspartame in a not unrealistically high dose produced a marked and persistent increase of the availability of Phe to the brain, which was not observed after protein intake. The study indicated, furthermore, that Phe was cleared faster from the plasma after consumption of protein compared with aspartame. PMID:1946186

  20. Methodology for detecting residual phosphoric acid in polybenzoxazole fibers.

    Science.gov (United States)

    Park, Eun Su; Sieber, John; Guttman, Charles; Rice, Kirk; Flynn, Kathleen; Watson, Stephanie; Holmes, Gale

    2009-12-01

    Because of the premature failure of in-service soft-body armor containing the ballistic fiber poly[(benzo-[1,2-d:5,4-d']-benzoxazole-2,6-diyl)-1,4-phenylene] (PBO), the Office of Law Enforcement Standards (OLES) at the National Institute of Standards and Technology (NIST) initiated a research program to investigate the reasons for this failure and to develop testing methodologies and protocols to ensure that these types of failures do not reoccur. In a report that focused on the stability of the benzoxazole ring that is characteristic of PBO fibers, Holmes, G. A.; Rice, K.; Snyder, C. R. J. Mater. Sci. 2006, 41, 4105-4116, showed that the benzoxazole ring was susceptible to hydrolytic degradation under acid conditions. Because of the processing conditions for the fibers, it is suspected by many researchers that residual phosphoric acid may cause degradation of the benzoxazole ring resulting in a reduction of ballistic performance. Prior to this work, no definitive data have indicated the presence of phosphoric acid since the residual phosphorus is not easily extracted and the processed fibers are known to incorporate phosphorus containing processing aids. Methods to efficiently extract phosphorus from PBO are described in this article. Further, characterization determined that the majority of the extractable phosphorus in PBO was attributed to the octyldecyl phosphate processing aid with some phosphoric acid being detected. Analysis by matrix assisted laser desorption ionization of model PBO oligomers indicates that the nonextractable phosphorus is attached to the PBO polymer chain as a monoaryl phosphate ester. The response of model aryl phosphates to NaOH exposure indicates that monoaryl phosphate ester is stable to NaOH washes used in the manufacturing process to neutralize the phosphoric acid reaction medium and to extract residual phosphorus impurities. PMID:19899783

  1. Methodology for detecting residual phosphoric acid in polybenzoxazole fibers.

    Science.gov (United States)

    Park, Eun Su; Sieber, John; Guttman, Charles; Rice, Kirk; Flynn, Kathleen; Watson, Stephanie; Holmes, Gale

    2009-12-01

    Because of the premature failure of in-service soft-body armor containing the ballistic fiber poly[(benzo-[1,2-d:5,4-d']-benzoxazole-2,6-diyl)-1,4-phenylene] (PBO), the Office of Law Enforcement Standards (OLES) at the National Institute of Standards and Technology (NIST) initiated a research program to investigate the reasons for this failure and to develop testing methodologies and protocols to ensure that these types of failures do not reoccur. In a report that focused on the stability of the benzoxazole ring that is characteristic of PBO fibers, Holmes, G. A.; Rice, K.; Snyder, C. R. J. Mater. Sci. 2006, 41, 4105-4116, showed that the benzoxazole ring was susceptible to hydrolytic degradation under acid conditions. Because of the processing conditions for the fibers, it is suspected by many researchers that residual phosphoric acid may cause degradation of the benzoxazole ring resulting in a reduction of ballistic performance. Prior to this work, no definitive data have indicated the presence of phosphoric acid since the residual phosphorus is not easily extracted and the processed fibers are known to incorporate phosphorus containing processing aids. Methods to efficiently extract phosphorus from PBO are described in this article. Further, characterization determined that the majority of the extractable phosphorus in PBO was attributed to the octyldecyl phosphate processing aid with some phosphoric acid being detected. Analysis by matrix assisted laser desorption ionization of model PBO oligomers indicates that the nonextractable phosphorus is attached to the PBO polymer chain as a monoaryl phosphate ester. The response of model aryl phosphates to NaOH exposure indicates that monoaryl phosphate ester is stable to NaOH washes used in the manufacturing process to neutralize the phosphoric acid reaction medium and to extract residual phosphorus impurities.

  2. Contributions of Individual Amino Acid Residues to the Endogenous CLV3 Function in Shoot Apical Meristem Maintenance in Arabidopsis

    Institute of Scientific and Technical Information of China (English)

    Xiu-Fen Song; Da-Li Yu; Ting-Ting Xu; Shi-Chao Ren; Peng Guo; Chun-Ming Liu

    2012-01-01

    As a peptide hormone,CLV3 restricts the stem cell number in shoot apical meristem (SAM) by interacting with CLV1/CLV2/CRN/RPK2 receptor complexes.To elucidate howthe function of the CLV3 peptide in SAM maintenance is established at the amino acid (AA) level,alanine substitutions were performed by introducing point mutations to individual residues in the peptide-coding region of CLV3 and its flanking sequences.Constructs carrying such substitutions,expressed under the control of CLV3 regulatory elements,were transformed to the clv3-2 null mutant to evaluate their efficiencies in complementing its defects in SAMs in vivo.These studies showed that aspartate-8,histidine-11,glycine-6,proline-4,arginine-1,and proline-9,arranged in an order of importance,were critical,while threonine-2,valine-3,serine-5,and the previously assigned hydroxylation and arabinosylation residue proline-7 were trivial for the endogenous CLV3 function in SAM maintenance.In contrast,substitutions of flanking residues did not impose much damage on CLV3.Complementation of different alanine-substituted constructs was confirmed by measurements of the sizes of SAMs and the WUS expression levels in transgenic plants.These studies established a complete contribution map of individual residues in the peptide-coding region of CLV3 for its function in SAM,which may help to understand peptide hormones in general.

  3. Arginine-glycine-aspartic acid-polyethylene glycol-polyamidoamine dendrimer conjugate improves liver-cell aggregation and function in 3-D spheroid culture.

    Science.gov (United States)

    Chen, Zhanfei; Lian, Fen; Wang, Xiaoqian; Chen, Yanling; Tang, Nanhong

    2016-01-01

    The polyamidoamine (PAMAM) dendrimer, a type of macromolecule material, has been used in spheroidal cell culture and drug delivery in recent years. However, PAMAM is not involved in the study of hepatic cell-spheroid culture or its biological activity, particularly in detoxification function. Here, we constructed a PAMAM-dendrimer conjugate decorated by an integrin ligand: arginine-glycine-aspartic acid (RGD) peptide. Our studies demonstrate that RGD-polyethylene glycol (PEG)-PAMAM conjugates can promote singly floating hepatic cells to aggregate together in a sphere-like growth with a weak reactive oxygen species. Moreover, RGD-PEG-PAMAM conjugates can activate the AKT-MAPK pathway in hepatic cells to promote cell proliferation and improve basic function and ammonia metabolism. Together, our data support the hepatocyte sphere treated by RGD-PEG-PAMAM conjugates as a potential source of hepatic cells for a biological artificial liver system. PMID:27621619

  4. Removal of coagulant aluminum from water treatment residuals by acid.

    Science.gov (United States)

    Okuda, Tetsuji; Nishijima, Wataru; Sugimoto, Mayo; Saka, Naoyuki; Nakai, Satoshi; Tanabe, Kazuyasu; Ito, Junki; Takenaka, Kenji; Okada, Mitsumasa

    2014-09-01

    Sediment sludge during coagulation and sedimentation in drinking water treatment is called "water treatment residuals (WTR)". Polyaluminum chloride (PAC) is mainly used as a coagulant in Japan. The recycling of WTR has been desired; one method for its reuse is as plowed soil. However, WTR reuse in this way is inhibited by the aluminum from the added PAC, because of its high adsorption capacity for phosphate and other fertilizer components. The removal of such aluminum from WTR would therefore be advantageous for its reuse as plowed soil; this research clarified the effect of acid washing on aluminum removal from WTR and on plant growth in the treated soil. The percentage of aluminum removal from raw WTR by sulphuric acid solution was around 90% at pH 3, the percentage decreasing to 40% in the case of a sun-dried sample. The maximum phosphate adsorption capacity was decreased and the available phosphorus was increased by acid washing, with 90% of aluminum removal. The enhancement of Japanese mustard spinach growth and the increased in plant uptake of phosphates following acid washing were observed.

  5. Synthesis and characterization of novel water-soluble polyamide based on spermine and aspartic acid as a potential gene delivery vehicle

    Directory of Open Access Journals (Sweden)

    2008-05-01

    Full Text Available We developed a novel and convenient method for the synthesis of a potentially safe non-viral gene delivery vehicle based on the cationic block copolymer of spermine and aspartic acid (ASSP and coupled it with polyethylene glycol (PEG. The copolymer ASSP was prepared by direct polycondensation in the ionic liquid, butylmethylimidazolium hexafluorophosphate, using triphenyl phosphite as the condensing agent under mild reaction conditions. The highly hydrophobic ASSP was transformed into a water soluble hydrophilic micelle by coupling ASSP with polyethylene glycol (PEG using the same ionic liquid and 1,1-carbonyl diimidazole as the condensing agent without harsh conditions. The polycationic ASSP-PEG was then used to condense calf thymus and plasmid deoxyribonuclceic acids (DNAs in Tris-HCl buffer (pH 7.4 to get a series of block ionomer complexes with various charge ratios. The physicochemical properties of the copolymer micelle and the DNA polyplexes were studied using fourier transform-infrared (FTIR, nuclear magnetic resonance (NMR and circular dichroism (CD spectroscopy, matrix assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS, differential scanning calorimetry (DSC, transmission electron microscopy (TEM and particle size measurements. It was observed that the DNA was condensed to compact particles by its interaction with the copolymer. Since DNA condensation to nano/micrometer sized particles is essential for gene delivery, our results indicate a potential use of the copolymer for gene delivery applications.

  6. Proteomic Investigation of Protein Profile Changes and Amino Acid Residue Level Modification in Cooked Lamb Meat: The Effect of Boiling.

    Science.gov (United States)

    Yu, Tzer-Yang; Morton, James D; Clerens, Stefan; Dyer, Jolon M

    2015-10-21

    Hydrothermal treatment (heating in water) is a common method of general food processing and preparation. For red-meat-based foods, boiling is common; however, how the molecular level effects of this treatment correlate to the overall food properties is not yet well-understood. The effects of differing boiling times on lamb meat and the resultant cooking water were here examined through proteomic evaluation. The longer boiling time was found to result in increased protein aggregation involving particularly proteins such as glyceraldehyde-3-phosphate dehydrogenase, as well as truncation in proteins such as in α-actinin-2. Heat-induced protein backbone cleavage was observed adjacent to aspartic acid and asparagine residues. Side-chain modifications of amino acid residues resulting from the heating, including oxidation of phenylalanine and formation of carboxyethyllysine, were characterized in the cooked samples. Actin and myoglobin bands from the cooked meat per se remained visible on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, even after significant cooking time. These proteins were also found to be the major source of observed heat-induced modifications. This study provides new insights into molecular-level modifications occurring in lamb meat proteins during boiling and a protein chemistry basis for better understanding the effect of this common treatment on the nutritional and functional properties of red-meat-based foods.

  7. The Nature of Intermolecular Interactions Between Aromatic Amino Acid Residues

    Energy Technology Data Exchange (ETDEWEB)

    Gervasio, Francesco; Chelli, Riccardo; Procacci, Piero; Schettino, Vincenzo

    2002-05-01

    The nature of intermolecular interactions between aromatic amino acid residues has been investigated by a combination of molecular dynamics and ab initio methods. The potential energy surface of various interacting pairs, including tryptophan, phenilalanine, and tyrosine, was scanned for determining all the relevant local minima by a combined molecular dynamics and conjugate gradient methodology with the AMBER force field. For each of these minima, single-point correlated ab initio calculations of the binding energy were performed. The agreement between empirical force field and ab initio binding energies of the minimum energy structures is excellent. Aromatic-aromatic interactions can be rationalized on the basis of electrostatic and van der Waals interactions, whereas charge transfer or polarization phenomena are small for all intermolecular complexes and, particularly, for stacked structures.

  8. Water-soluble lipopolymer delivery of N-methyl-D-aspartic acid receptor 2B siRNA relieves chronic neuropathic pain in rats

    Institute of Scientific and Technical Information of China (English)

    Jianhua Lu; Yuanxiang Tao; Xue Yang; Weifeng Tu; Hao Chen; Jiaxiang Xiong; Chungui Hu

    2011-01-01

    Spinal dorsal horn N-Methyl-D-aspartic acid receptor 2B (NR2B) overexpression plays an important role in the production and maintenance of neuropathic pain. Because small interfering RNA (siRNA) can inhibit NR2B expression, siRNA may provide a novel approach to treat neuropathic pain and possibly nerve injury. However, an efficient and safe vector for NR2B siRNA has not been discovered. This study shows that a water soluble lipopolymer (WSLP) comprised of low molecular weight polyethyleneimine (PEI) and cholesterol can deliver siRNA targeting NR2B for the treatment of neuropathic pain. Results show that intrathecal injection of WSLP/siRNA complexes for 3 days inhibit NR2B gene expression with reductions in mRNA and protein levels by 59% and 54%, respectively, compared with control rats (P < 0.01). Injection of WSLP complexed with scrambled siRNA, or PEI with siRNA did not show this inhibitory effect. Moreover, injection of WSLP/siRNA complexes significantly relieved neuropathic pain at 3, 7, 12, and 21 days, while injection of WSLP with scrambled siRNA or PEI with siRNA did not. These results demonstrate that WSLP can efficiently deliver siRNA targeting NR2B in vivo and relieve neuropathic pain.

  9. Static and dynamic investigations of poly(aspartic acid) and Pluronic F127 complex prepared by self-assembling in aqueous solution

    Science.gov (United States)

    Nita, Loredana E.; Chiriac, Aurica P.; Bercea, Maria; Nistor, Manuela T.

    2015-12-01

    The present investigation is focused on evaluation of self-assembling ability in aqueous solutions of two water soluble polymers: poly(aspartic acid) (PAS) and Pluronic F127 (PL). The intermolecular complexes, realized between polyacid and neutral copolymer surfactant in different ratios, have been studied by combining various characterization techniques as rheology, DLS, spectroscopy, microscopy, chemical imaging, and zeta potential determination, measurements performed in static and/or dynamic conditions. In static conditions, when the equilibrium state between PAS/PL polymeric pair was reached, and depending on the polymers mixture composition, and of experimental rheological conditions, positive or negative deviations from the additive rule are registered. Conformational changes of the macromolecular chains and correspondingly physical interactions are generated between PL and PAS for self-assembly and the formation of interpolymer complex as suprastructure with micellar configuration. The phenomenon was better evidenced in case of 1/1 wt ratio between the two polymers. In dynamic conditions of determination, during "in situ" evaluation of the hydrodynamic diameter, zeta potential and conductivity, when the equilibrium state is not reached and as result either the intermolecular bonds are not achieved, the self-assembling process is not so obvious evidenced.

  10. Accumulation of radioactivity in rat brain and peripheral tissues including salivary gland after intravenous administration of {sup 14}C-D-aspartic acid

    Energy Technology Data Exchange (ETDEWEB)

    Imai, Kazuhiro; Fukushima, Takeshi; Santa, Tomofumi; Homma, Hiroshi [Tokyo Univ. (Japan). Faculty of Pharmaceutical Sciences; Sugihara, Juko; Kodama, Hirohiko; Yoshikawa, Masayoshi

    1997-03-01

    After the intravenous administration of {sup 14}C-D-aspartic acid (Asp) into Sprague-Dawley rats (male, 7-week-old), the distribution and elimination of radioactivity was investigated by the whole body autoradiography. High radioactivities were detected in pineal gland, pituitary gland and salivary gland at 30 min after administration. The other tissues detected were liver, lung, adrenal gland, pancreas and spleen where D-Asp was reported to occur naturally. After 24 hr, the radioactivities were still detected at high levels in the pineal, pituitary and salivary glands. The data suggested the natural occurrence of D-Asp in salivary gland. After careful examination utilizing fluorescent derivatization and chiral separation by high-performance liquid chromatography, the presence of D-Asp was, for the first time, demonstrated in salivary gland in situ, the concentration of which was 7.85 {+-} 1.0 nmol/g. The administration of {sup 14}C-L-Asp was also carried out. The data suggested that D-Asp in the circulating blood is one of the sources of the tissue D-Asp. (author)

  11. Cell-free production of integral membrane aspartic acid proteases reveals zinc-dependent methyltransferase activity of the Pseudomonas aeruginosa prepilin peptidase PilD

    Science.gov (United States)

    Aly, Khaled A; Beebe, Emily T; Chan, Chi H; Goren, Michael A; Sepúlveda, Carolina; Makino, Shin-ichi; Fox, Brian G; Forest, Katrina T

    2013-01-01

    Integral membrane aspartic acid proteases are receiving growing recognition for their fundamental roles in cellular physiology of eukaryotes and prokaryotes, and may be medically important pharmaceutical targets. The Gram-negative Pseudomonas aeruginosa PilD and the archaeal Methanococcus voltae FlaK were synthesized in the presence of unilamellar liposomes in a cell-free translation system. Cosynthesis of PilD with its full-length substrate, PilA, or of FlaK with its full-length substrate, FlaB2, led to complete cleavage of the substrate signal peptides. Scaled-up synthesis of PilD, followed by solubilization in dodecyl-β-d-maltoside and chromatography, led to a pure enzyme that retained both of its known biochemical activities: cleavage of the PilA signal peptide and S-adenosyl methionine-dependent methylation of the mature pilin. X-ray fluorescence scans show for the first time that PilD is a zinc-binding protein. Zinc is required for the N-terminal methylation of the mature pilin, but not for signal peptide cleavage. Taken together, our work identifies the P. aeruginosa prepilin peptidase PilD as a zinc-dependent N-methyltransferase and provides a new platform for large-scale synthesis of PilD and other integral membrane proteases important for basic microbial physiology and virulence. PMID:23255525

  12. Application of L-Aspartic Acid-Capped ZnS:Mn Colloidal Nanocrystals as a Photosensor for the Detection of Copper (II Ions in Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Jungho Heo

    2016-04-01

    Full Text Available Water-dispersible ZnS:Mn nanocrystals (NCs were synthesized by capping the surface with polar L-aspartic acid (Asp molecules. The obtained ZnS:Mn-Asp NC product was optically and physically characterized using the corresponding spectroscopic methods. The ultra violet-visible (UV-VIS absorption spectrum and photoluminescence (PL emission spectrum of the NCs showed broad peaks at 320 and 590 nm, respectively. The average particle size measured from the obtained high resolution-transmission electron microscopy (HR-TEM image was 5.25 nm, which was also in accordance with the Debye-Scherrer calculations using the X-ray diffraction (XRD data. Moreover, the surface charge and degree of aggregation of the ZnS:Mn-Asp NCs were determined by electrophoretic and hydrodynamic light scattering methods, respectively. These results indicated the formation of agglomerates in water with an average size of 19.8 nm, and a negative surface charge (−4.58 mV in water at ambient temperature. The negatively-charged NCs were applied as a photosensor for the detection of specific cations in aqueous solution. Accordingly, the ZnS:Mn-Asp NCs showed an exclusive luminescence quenching upon addition of copper (II cations. The kinetic mechanism study on the luminescence quenching of the NCs by the addition of the Cu2+ ions proposed an energy transfer through the ionic binding between the two oppositely-charged ZnS:Mn-Asp NCs and Cu2+ ions.

  13. Effect of Xingnaojing Injection(醒脑静注射液)on Hippocampal N—methyl—D—aspartic Acid Receptors of Focal Cerebral Ischemia in Rats

    Institute of Scientific and Technical Information of China (English)

    SHENSi-yu; CAIDing-fang; 等

    2003-01-01

    Objective:To observe and elucidate the neuroprotective effect of Xingnaojing(XNJ) injec-tion on hippocampal N-methyl-D-aspartic acid(NMDA) receptors of focal cerebral ischemia in rats.Meth-ods:Cerebral ischemia was established by occluding the middle cerebral artery with an intraluminal suture technique in rats.Neurological deficit score,infarct volume and quantity of NMDA receptors were esti-mated in all groups and compared.Results:After being treated with XNJ,the score decreased in the initial 6 hours and infarct volume decreased in 24 hours.And within 24 hours,the quantity of NMDA receptors obviously decreased compared with the model group(P<0.01).It indicated that XNJ could ameliorate neurological behavior of middle cerebral artery occlusion rats and down-regulate the expression of hipp-ocampal NMDA receptors.Conclusion:The neuroprotective effect of XNJ on focal cerebral ischemia is possibly related to down-regulating the expression of NMDA receptors in rats.

  14. Toxicity assessment of repeated intravenous injections of arginine–glycine–aspartic acid peptide conjugated CdSeTe/ZnS quantum dots in mice

    Directory of Open Access Journals (Sweden)

    Wang YW

    2014-10-01

    Full Text Available You-Wei Wang, Kai Yang, Hong Tang, Dan Chen, Yun-Long Bai Department of Oral and Maxillofacial Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, People’s Republic of China Background: Nanotechnology-based near-infrared quantum dots (NIR QDs have many excellent optical properties, such as high fluorescence intensity, good fluorescence stability, and strong tissue-penetrating ability. Integrin αvß3 is highly and specifically expressed in tumor angiogenic vessel endothelial cells of almost all carcinomas. Recent studies have shown that NIR QDs linked to peptides containing the arginine–glycine–aspartic acid (RGD sequence (NIR QDs-RGD can specifically target integrin αvß3 expressed in endothelial cells of tumor angiogenic vessels in vivo, and they offer great potential for early cancer diagnosis, in vivo tumor imaging, and tumor individualized therapy. However, the toxicity profile of NIR QDs-RGD has not been reported. This study was conducted to investigate the toxicity of NIR QDs-RGD when intravenously administered to mice singly and repeatedly at the dose required for successful tumor imaging in vivo.Materials and methods: A NIR QDs-RGD probe was prepared by linking NIR QDs with the maximum emission wavelength of 800 nm (QD800 to the RGD peptide (QD800-RGD. QD800-RGD was intravenously injected to BALB/C mice once or twice (200 pmol equivalent of QD800 for each injection. phosphate-buffered saline solution was used as control. Fourteen days postinjection, toxicity tests were performed, including complete blood count (white blood cell, red blood cell, hemoglobin, platelets, lymphocytes, and neutrophils and serum biochemical analysis (total protein, albumin, albumin/globulin, aspartate aminotransferase, alanine aminotransferase, and blood urea nitrogen. The coefficients of liver, spleen, kidney, and lung weight to body weight were measured, as well as their oxidation and antioxidation indicators, including

  15. Microwave-assisted synthesis, crystal structure and toxicity of L-aspartic acid zinc spiral linear supramolecular polymer

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Youming; LIN; Qi; WEI; Taibao

    2004-01-01

    [1]Prasad, A.S. Nutritional metabolic role of zinc, Fed. Proc., 1967,26(1): 172-185.[2]Slagueiro, M. J., Zubillaga, M. B., Lysionek, A. E. et al., The role of zinc in the growth and development of children, Nutrition,2002, 18: 510-519.[3]Mossad, S. B., Zinc and the common cold: Are we close to a true?Nutrition, 1997, 13: 708-709.[4]Prasad, A. S., Clinical and biochemical manifestations of zinc deficiency in human subjects, J. Am. Coll. Nutr., 1985, 4(1):73-82.[5]Prasad, A. S., Zinc deficiency in sickle cell disease, Prog. Clin.Biol. Res., 1984, 165: 49-58.[6]Prasad, A. S., Discovery of zinc deficiency: Impact on human health, Nutrition, 2001, 17: 685-687.[7]Gao, S. -L., Fan, Y., Hu, R. -Z. et al., Synthesis, properties and phase equilibrian of Zn(NO3)2-Leu-H2O system (25℃), Chem. J.Chinese Universities (in Chinese), 2003, 24(2): 195-199.[8]Viladkar, S., Kamaluddin, Nath, M., Hydrolysis of phosphate by (amino acidato)zinc complexes, Bull. Chem. Soc. Jpn., 1993,66(10): 2922-2926.[9]Ashby, C. I. H., Paton, W. F., Brown, T. L., Nitrogen-14 nuclear quadrupole resonance spectra of the coordinated amino group and of coordinated imidazole. Crystal and molecular structures of chloroglycylglycinato(imidazole)cadmium, J. Am. Chem. Soc.,1980, 102(9): 2990-2998.[10]Jia, D. -Z., Yang, L. -X., Xia, X. et al., Studies on application of microwave heating techniques for the solid state reactions of coordination Compounds (Ⅰ), Chem. J. Chinese Universities (in Chinese), 1997, 18(9): 1432-1435.[11]Lidstrom, P., Tierney, J., Wathey, B. et al., Microwave assisted organic synthesis-a review, Tetrahedron, 2001, 57: 9925-9283.[12]Zhang, Y. M., Bai, J. F., Lu, M. Q. et al., Preparation of amino-acid Zinc and its character, Huaxue Shijie (in Chinese),1997, (2): 82-84.

  16. Chemical Modification of Amino Acid Residues in Human Plasminogen

    Institute of Scientific and Technical Information of China (English)

    LIANG Fang; SUN Hong; ZHAO Cheng-guang; CUI Ting; HONG Shui-sheng; CHEN Jia; LIU Lan-ying

    2003-01-01

    The chemical modification of human plasminogen(HPg) was studied with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide(EDC), N-acetylimidazole(NAI), 1,2-cyclohexanedione(CHD), chloramine T(Ch-T) and N-bromosuccinimide(NBS) as modifying reagents at its carboxyl group, tyrosine, arginine, methionine and tryptophan residues, respectively. The results indicate that tyrosine and arginine residues are not essential for HPg activity, while carboxyl groups, methionine and tryptophan residues are important for the activity of HPg. The Keech and Farrant′s kinetic analysis reveals that one tryptophan residue, one methionine residue and two carboxyl groups are essential for HPg activity.

  17. Effect of Amino Acid Residue and Oligosaccharide Chain Chemical Modifications on Spectral and Hemagglutinating Activity of Millettia dielsiana Harms. ex Diels. Lectin

    Institute of Scientific and Technical Information of China (English)

    Shun GAO; Jie AN; Chuan-Fang WU; Ying GU; Fang CHEN; Yuan YU; Qia-Qing WU; Jin-Ku BAO

    2005-01-01

    The effects of modifying the carbohydrate chain and amino acids on the conformation and activity of Millettia dielsiana Harms. ex Diels. lectin (MDL) were studied by hemagglutination, fluorescence and circular dichroism analysis. The modification of tryptophan residues led to a compete loss of hemagglutinating activity; however, the addition of mannose was able to prevent this loss of activity. The results indicate that two tryptophan residues are involved in the carbohydrate-binding site. Modifications of the carboxyl group residues produced an 80% loss of activity, but the presence of mannose protected against the modification. The results suggest that the carboxyl groups of aspartic and glutamic acids are involved in the carbohydrate-binding site of the lectin. However, oxidation of the carbohydrate chain and modification of the histidine and arginine residues did not affect the hemagglutinating activity of MDL. Fluorescence studies of MDL indicate that tryptophan residues are present in a relatively hydrophobic region, and the binding of mannose to MDL could quench tryptophan fluorescence without any change in λmax. The circular dichroism spectrum showed that all of these modifications affected the conformation of the MDL molecule to different extents, except the modification of arginine residues. Fluorescence quenching showed that acrylamide and iodoacetic acids are able to quench 77% and 98% of the fluorescence of tryptophan in MDL, respectively.However, KI produced a barely perceptible effect on the fluorescence of MDL, even when the concentration of I- was 0.15 M. This demonstrates that most of tryptophan residues are located in relatively hydrophobic or negatively charged areas near the surface of the MDL molecule.

  18. Oxidation in Acidic Medium of Lignins from Agricultural Residues

    Science.gov (United States)

    Labat, Gisele Aparecida Amaral; Gonçalves, Adilson Roberto

    Agricultural residues as sugarcane straw and bagasse are burned in boilers for generation of energy in sugar and alcohol industries. However, excess of those by-products could be used to obtain products with higher value. Pulping process generates cellulosic pulps and lignin. The lignin could be oxidized and applied in effluent treatments for heavy metal removal. Oxidized lignin presents very strong chelating properties. Lignins from sugarcane straw and bagasse were obtained by ethanol-water pulping. Oxidation of lignins was carried out using acetic acid and Co/Mn/Br catalytical system at 50, 80, and 115 °C for 5 h. Kinetics of the reaction was accomplished by measuring the UV-visible region. Activation energy was calculated for lignins from sugarcane straw and bagasse (34.2 and 23.4 kJ mol-1, respectively). The first value indicates higher cross-linked formation. Fourier-transformed infrared spectroscopy data of samples collected during oxidation are very similar. Principal component analysis applied to spectra shows only slight structure modifications in lignins after oxidation reaction.

  19. A conserved aspartic acid is important for agonist (VUAA1 and odorant/tuning receptor-dependent activation of the insect odorant co-receptor (Orco.

    Directory of Open Access Journals (Sweden)

    Brijesh N Kumar

    Full Text Available Insect odorant receptors function as heteromeric odorant-gated cation channels comprising a conventional odorant-sensitive tuning receptor, and a conserved co-receptor (Orco. An Orco agonist, VUAA1, is able to activate both heteromeric and homomeric Orco-containing channels. Very little is known about specific residues in Orco that contribute to cation permeability and gating. We investigated the importance of two conserved Asp residues, one in each of transmembrane domains 5 and 7, for channel function by mutagenesis. Drosophila melanogaster Orco and its substitution mutants were expressed in HEK cells and VUAA1-stimulated channel activity was determined by Ca(2+ influx and whole-cell patch clamp electrophysiology. Substitution of D466 in transmembrane 7 with amino acids other than glutamic acid resulted in a substantial reduction in channel activity. The D466E Orco substitution mutant was ~2 times more sensitive to VUAA1. The permeability of the D466E Orco mutant to cations was unchanged relative to wild-type Orco. When D466E Orco is co-expressed with a conventional tuning odorant receptor, the heteromeric complex also shows increased sensitivity to an odorant. Thus, the effect of the D466E mutation is not specific to VUAA1 agonism or dependent on homomeric Orco assembly. We suggest the gain-of-activation characteristic of the D466E mutant identifies an amino acid that is likely to be important for activation of both heteromeric and homomeric insect odorant receptor channels.

  20. Demonstration on Fertilizer Effect of Poly Aspartic Acid on Rice%聚天冬氨酸增效肥在水稻上的应用效果示范

    Institute of Scientific and Technical Information of China (English)

    李梅; 沈文忠; 左其东; 张绪美

    2015-01-01

    Objective] The aim was to provide references for poly aspartic acid applied on rice. [Method] The fertilizer effect of poly aspartic acid on rice was studied, by conducting test. [Result] The results showed that rice plant height increased 2.67 cm compared with conventional fertilization way, and increased 2.97%, by applying poly aspartic acid on rice. The effective panicles increased 25500 ears, and increased the amplitude of 0.85%. Empty abortive rate decreased by 7.26%. Rice yield increased significantly with increase of 635.7 kg/hm2, with the production rate of 8.11%. [Conclusion] Application of poly aspartic acid could obtain obvious increase production effect in the process of rice production.%[目的]为聚天冬氨酸增效肥在水稻上的应用提供技术支撑。[方法]针对聚天冬氨酸增效肥在水稻上应用的实际效果进行试验。[结果]结果表明,与常规施肥方式相比,施用了聚天冬氨酸增效肥的水稻株高增加了2.67 cm,增幅为2.97%;有效穗数增加2.55万穗,增幅为0.85%;空秕率减少了7.26%;水稻产量明显增加,增产635.7 kg/hm2,增产率为8.11%。[结论]水稻生产过程中施用聚天冬氨酸增效肥可取得明显增产增收效果。

  1. Plant residues: short term effect on sulphate, borate, zinc and copper adsorption by an acid oxisol

    OpenAIRE

    2003-01-01

    Laboratory experiments were carried out to examine the effects of plant residues on Cu, Zn, B and S adsorption by an acidic oxisol. The plant residues were: black oats (Avena strigosa), oil seed radish(Raphanus sativus), velvet beans (Stizolobium cinereum), and pigeon pea (Cajanus cajan) collected at flowering stage. Plant residues increased Cu and Zn adsorptions and decreased B and S adsorptions. The results indicated that for short term effect plant residues decreased the availabilities of ...

  2. Properties of nanocellulose isolated from corncob residue using sulfuric acid, formic acid, oxidative and mechanical methods.

    Science.gov (United States)

    Liu, Chao; Li, Bin; Du, Haishun; Lv, Dong; Zhang, Yuedong; Yu, Guang; Mu, Xindong; Peng, Hui

    2016-10-20

    In this work, nanocellulose was extracted from bleached corncob residue (CCR), an underutilized lignocellulose waste from furfural industry, using four different methods (i.e. sulfuric acid hydrolysis, formic acid (FA) hydrolysis, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation, and pulp refining, respectively). The self-assembled structure, morphology, dimension, crystallinity, chemical structure and thermal stability of prepared nanocellulose were investigated. FA hydrolysis produced longer cellulose nanocrystals (CNCs) than the one obtained by sulfuric acid hydrolysis, and resulted in high crystallinity and thermal stability due to its preferential degradation of amorphous cellulose and lignin. The cellulose nanofibrils (CNFs) with fine and individualized structure could be isolated by TEMPO-mediated oxidation. In comparison with other nanocellulose products, the intensive pulp refining led to the CNFs with the longest length and the thickest diameter. This comparative study can help to provide an insight into the utilization of CCR as a potential source for nanocellulose production. PMID:27474618

  3. Dataset of cocoa aspartic protease cleavage sites.

    Science.gov (United States)

    Janek, Katharina; Niewienda, Agathe; Wöstemeyer, Johannes; Voigt, Jürgen

    2016-09-01

    The data provide information in support of the research article, "The cleavage specificity of the aspartic protease of cocoa beans involved in the generation of the cocoa-specific aroma precursors" (Janek et al., 2016) [1]. Three different protein substrates were partially digested with the aspartic protease isolated from cocoa beans and commercial pepsin, respectively. The obtained peptide fragments were analyzed by matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/TOF-MS/MS) and identified using the MASCOT server. The N- and C-terminal ends of the peptide fragments were used to identify the corresponding in-vitro cleavage sites by comparison with the amino acid sequences of the substrate proteins. The same procedure was applied to identify the cleavage sites used by the cocoa aspartic protease during cocoa fermentation starting from the published amino acid sequences of oligopeptides isolated from fermented cocoa beans. PMID:27508221

  4. Dataset of cocoa aspartic protease cleavage sites

    Directory of Open Access Journals (Sweden)

    Katharina Janek

    2016-09-01

    Full Text Available The data provide information in support of the research article, “The cleavage specificity of the aspartic protease of cocoa beans involved in the generation of the cocoa-specific aroma precursors” (Janek et al., 2016 [1]. Three different protein substrates were partially digested with the aspartic protease isolated from cocoa beans and commercial pepsin, respectively. The obtained peptide fragments were analyzed by matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/TOF-MS/MS and identified using the MASCOT server. The N- and C-terminal ends of the peptide fragments were used to identify the corresponding in-vitro cleavage sites by comparison with the amino acid sequences of the substrate proteins. The same procedure was applied to identify the cleavage sites used by the cocoa aspartic protease during cocoa fermentation starting from the published amino acid sequences of oligopeptides isolated from fermented cocoa beans.

  5. Aspartate embedding depth affects pHLIP's insertion pKa.

    Science.gov (United States)

    Fendos, Justin; Barrera, Francisco N; Engelman, Donald M

    2013-07-01

    We have used the pHlow insertion peptide (pHLIP) family to study the role of aspartate embedding depth in pH-dependent transmembrane peptide insertion. pHLIP binds to the surface of a lipid bilayer as a largely unstructured monomer at neutral pH. When the pH is lowered, pHLIP inserts spontaneously across the membrane as a spanning α-helix. pHLIP insertion is reversible when the pH is adjusted back to a neutral value. One of the critical events facilitating pHLIP insertion is the protonation of aspartates in the spanning domain of the peptide: the negative side chains of these residues convert to uncharged, polar forms, facilitating insertion by altering the hydrophobicity of the spanning domain. To examine this protonation mechanism further, we created pHLIP sequence variants in which the two spanning aspartates (D14 and D25) were moved up or down in the sequence. We hypothesized that the aspartate depth in the inserted state would directly affect the proton affinity of the acidic side chains, altering the pKa of pH-dependent insertion. To this end, we also mutated the arginine at position 11 to determine whether arginine snorkeling modulates the insertion pKa by affecting the aspartate depth. Our results indicate that both types of mutations change the insertion pKa, supporting the idea that the aspartate depth is a participating parameter in determining the pH dependence. We also show that pHLIP's resistance to aggregation can be altered with our mutations, identifying a new criterion for improving the performance of pHLIP in vivo when targeting acidic disease tissues such as cancer and inflammation. PMID:23721379

  6. Expression of N-methyl-D-aspartic acid 2A-B and 2B receptors in anterior thalamic nucleus and subiculum complex of rats

    Institute of Scientific and Technical Information of China (English)

    Yuanshan Fu; Xiaokai Ma; Xiaoling Yue; Bin Wang

    2008-01-01

    BACKGROUND: Glutamate acid ionotropic receptor N-methyl-D-aspartic acid (NMDA) takes part in long-term potentiation, thereby influencing the process of learning and memory.OBJECTIVE: To verify expression of NMDA 2A/B and 2B receptors in the anterior thalamic nucleus and subieulum complex of rats.DESIGN, TIME AND SETTING: A single-sample observation was performed at Department of Anatomy in Dalian Mcdical University (Dalian, Liaoning, China) from April to September in 2007.MATERIALS: Ten adult Wistar rats were used for this study, as well as rabbit anti-NMDA 2A/B and 2Bantibodies.METHODS: The rats were anesthetized and perfused, followed by brain resection and coronal sectioning of the brain tissue. A 1:3 series was selected for immunohistochemistry, using antibodies specific to NMDA 2A/B and 2B receptors. Photos were taken using the Nikon image analysis system.MAIN OUTCOME MEASURES: Expression and distribution of immunohistochemistry staining of NMDA 2A/B and 2B receptor subunits.RESULTS: There were a large number of NMDA 2A/B and 2B receptor-positive neurons distributed throughout the anterior dorsal thalamic nucleus. In the anterior ventral thalamic nucleus, distribution of positive neurons was rare, staining intensity was lighter, and cell bodies were smaller compared with the anterior dorsal thalamic nucleus. In the subiculum complex, staining intensity of NMDA 2A/B and 2B-positive neurons was weakest in the molecular layer and stronger in the pyramidal layer, in particular the region with large cell bodies adjacent to the molecular layer. In the multiform layer, more positive neurons of various sizes were detected.CONCLUSION: NMDA 2A/B and 2B receptor subunits were richly distributed in the anterior thalamic nucleus, with a small difference existing between the anterior dorsal nucleus and anterior ventral nucleus.These neurons were also differentially distributed within the three layers of the subiculum complex.

  7. Divergent allosteric patterns verify the regulatory paradigm for aspartate transcarbamylase.

    Science.gov (United States)

    Wales, M E; Madison, L L; Glaser, S S; Wild, J R

    1999-12-17

    The native Escherichia coli aspartate transcarbamoylase (ATCase, E.C. 2.1.3.2) provides a classic allosteric model for the feedback inhibition of a biosynthetic pathway by its end products. Both E. coli and Erwinia herbicola possess ATCase holoenzymes which are dodecameric (2(c3):3(r2)) with 311 amino acid residues per catalytic monomer and 153 and 154 amino acid residues per regulatory (r) monomer, respectively. While the quaternary structures of the two enzymes are identical, the primary amino acid sequences have diverged by 14 % in the catalytic polypeptide and 20 % in the regulatory polypeptide. The amino acids proposed to be directly involved in the active site and nucleotide binding site are strictly conserved between the two enzymes; nonetheless, the two enzymes differ in their catalytic and regulatory characteristics. The E. coli enzyme has sigmoidal substrate binding with activation by ATP, and inhibition by CTP, while the E. herbicola enzyme has apparent first order kinetics at low substrate concentrations in the absence of allosteric ligands, no ATP activation and only slight CTP inhibition. In an apparently important and highly conserved characteristic, CTP and UTP impose strong synergistic inhibition on both enzymes. The co-operative binding of aspartate in the E. coli enzyme is correlated with a T-to-R conformational transition which appears to be greatly reduced in the E. herbicola enzyme, although the addition of inhibitory heterotropic ligands (CTP or CTP+UTP) re-establishes co-operative saturation kinetics. Hybrid holoenzymes assembled in vivo with catalytic subunits from E. herbicola and regulatory subunits from E. coli mimick the allosteric response of the native E. coli holoenzyme and exhibit ATP activation. The reverse hybrid, regulatory subunits from E. herbicola and catalytic subunits from E. coli, exhibited no response to ATP. The conserved structure and diverged functional characteristics of the E. herbicola enzyme provides an opportunity

  8. Contrôle de la vitesse de germination chez le maïs (Zea mays) : étude de la voie de biosynthèse des acides aminés issus de l'aspartate et recherche de QTLs

    OpenAIRE

    Anzala, Fabiola,

    2006-01-01

    The aspartate pathway was studied through the expression of the genes ask1, ask2 akh1 and akh2 coding for aspartate kinase by qt-RT-PCR, the amino acids content by HPLC and the degradation of asp-15N in the derived amino acids followed by labelling of 15N. It appears that the aspartate pathway differs between two (slow and fast) genotypes of maize: slow germination would be associated with an inhibiting effect of the accumulation of lysine or to limited contents of threonine and methionine. T...

  9. Optical imaging of head and neck squamous cell carcinoma in vivo using arginine-glycine- aspartic acid peptide conjugated near-infrared quantum dots

    Directory of Open Access Journals (Sweden)

    Huang H

    2013-12-01

    Full Text Available Hao Huang, Yun-Long Bai, Kai Yang, Hong Tang, You-Wei WangDepartment of Oral and Maxillofacial Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, People's Republic of ChinaAbstract: Molecular imaging plays a key role in personalized medicine and tumor diagnosis. Quantum dots with near-infrared emission spectra demonstrate excellent tissue penetration and photostability, and have recently emerged as important tools for in vivo tumor imaging. Integrin αvβ3 has been shown to be highly and specifically expressed in endothelial cells of tumor angiogenic vessels in almost all types of tumors, and specifically binds to the peptide containing arginine-glycine-aspartic acid (RGD. In this study, we conjugated RGD with quantum dots with emission wavelength of 800 nm (QD800 to generate QD800-RGD, and used it via intravenous injection as a probe to image tumors in nude mice bearing head and neck squamous cell carcinoma (HNSCC. Twelve hours after the injection, the mice were still alive and were sacrificed to isolate tumors and ten major organs for ex vivo analysis to localize the probe in these tissues. The results showed that QD800-RGD was specifically targeted to integrin αvβ3 in vitro and in vivo, producing clear tumor fluorescence images after the intravenous injection. The tumor-to-background ratio and size of tumor image were highest within 6 hours of the injection and declined significantly at 9 hours after the injection, but there was still a clearly visible tumor image at 12 hours. The greatest amount of QD800-RGD was found in liver and spleen, followed by tumor and lung, and a weak fluorescence signal was seen in tibia. No detectable signal of QD800-RGD was found in brain, heart, kidney, testis, stomach, or intestine. Our study demonstrated that using integrin αvβ3 as target, it is possible to use intravenously injected QD800-RGD to generate high quality images of HNSCC, and the technique offers great potential

  10. Fractional Precipitation of Amino Acids from Agro-industrial Residues Using Ethanol

    NARCIS (Netherlands)

    Widyarani, Rani; Bowden, Nathan A.; Kolfschoten, Ruben C.; Sanders, Johan P.M.; Bruins, Marieke E.

    2016-01-01

    Amino acids are important in human and animal diet, as well as being potential feedstocks for chemical production. Amino acids can be obtained from protein after hydrolysis. In addition, several agro-industrial residues already contain a mixture of free amino acids. The objective of this study wa

  11. On the distribution of amino acid residues in transmembrane alpha-helix bundles.

    OpenAIRE

    Samatey, F A; Xu, C.; Popot, J L

    1995-01-01

    The periodic distribution of residues in the sequence of 469 putative transmembrane alpha-helices from eukaryotic plasma membrane polytopic proteins has been analyzed with correlation matrices. The method does not involve any a priori assumption about the secondary structure of the segments or about the physicochemical properties of individual amino acid residues. Maximal correlation is observed at 3.6 residues per period, characteristic of alpha-helices. A scale extracted from the data descr...

  12. The effect of delignification process with alkaline peroxide on lactic acid production from furfural residues

    Directory of Open Access Journals (Sweden)

    Yong Tang

    2012-11-01

    Full Text Available Furfural residues produced from the furfural industry were investigated as a substrate for lactic acid production by simultaneous saccharification and fermentation (SSF. Alkaline peroxide was used for delignification of furfural residues to improve the final lactic acid concentration. The residue was treated with 1.3% to 1.7% hydrogen peroxide at 80 °C for 1 h with a substrate concentration of 3.33%. SSF of furfural residues with different delignification degrees were carried out to evaluate the effect of delignification degree on lactic acid production. Using corn hydrolysates/ furfural residues as substrates, SSF with different media were carried out to investigate the effect of lignin on the interaction between enzymes and lactic acid bacteria. Lactic acid bacteria had a negative effect on cellulase, thus resulting in the reduction of enzyme activity. Lignin and nutrients slowed down the decreasing trend of enzyme activity. A higher delignification resulted in a slower fermentation rate and lower yield due to degradation products of lignin and the effect of lignin on the interaction between enzymes and lactic acid bacteria. For the purpose of lactic acid production, a moderate delignification (furfural residues with the lignin content of 14.8% was optimum.

  13. 40 CFR 180.331 - 4-(2,4-Dichlorophenoxy) butyric acid; tolerances for residues.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false 4-(2,4-Dichlorophenoxy) butyric acid; tolerances for residues. 180.331 Section 180.331 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Specific Tolerances § 180.331...

  14. 40 CFR 180.318 - 4-(2-Methyl-4-chlorophenoxy) butyric acid; tolerance for residues.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false 4-(2-Methyl-4-chlorophenoxy) butyric acid; tolerance for residues. 180.318 Section 180.318 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Specific Tolerances § 180.318...

  15. Finding coevolving amino acid residues using row and column weighting of mutual information and multi-dimensional amino acid representation

    DEFF Research Database (Denmark)

    Oliveira, Rodrigo Gouveia; Pedersen, Anders Gorm

    2007-01-01

    ABSTRACT: BACKGROUND: Some amino acid residues functionally interact with each other. This interaction will result in an evolutionary co-variation between these residues - coevolution. Our goal is to find these coevolving residues. RESULTS: We present six new methods for detecting coevolving...... residues. Among other things, we suggest measures that are variants of Mutual Information, and measures that use a multidimensional representation of each residue in order to capture the physico-chemical similarities between amino acids. We created a benchmarking system, in silico, able to evaluate...... these methods through a wide range of realistic conditions. Finally, we use the combination of different methods as a way of improving performance. CONCLUSION: Our best method (Row and Column Weighed Mutual Information) has an estimated accuracy increase of 63% over Mutual Information. Furthermore, we show...

  16. Plant residues: short term effect on sulphate, borate, zinc and copper adsorption by an acid oxisol

    Directory of Open Access Journals (Sweden)

    Dias Ana Cristi Basile

    2003-01-01

    Full Text Available Laboratory experiments were carried out to examine the effects of plant residues on Cu, Zn, B and S adsorption by an acidic oxisol. The plant residues were: black oats (Avena strigosa, oil seed radish(Raphanus sativus, velvet beans (Stizolobium cinereum, and pigeon pea (Cajanus cajan collected at flowering stage. Plant residues increased Cu and Zn adsorptions and decreased B and S adsorptions. The results indicated that for short term effect plant residues decreased the availabilities of Cu and Zn through metal organic complex reactions and increased availabilities of S and B through competition with organic anions by the adsorption sites on soil.

  17. Optimization of acid hydrolysis from the hemicellulosic fraction of Eucalyptus grandis residue using response surface methodology.

    Science.gov (United States)

    Canettieri, Eliana Vieira; de Moraes Rocha, George Jackson; de Carvalho, João Andrade; de Almeida e Silva, João Batista

    2007-01-01

    Biotechnological conversion of biomass into fuels and chemicals requires hydrolysis of the polysaccharide fraction into monomeric sugars. Hydrolysis can be performed enzymatically and with dilute or concentrate mineral acids. The present study used dilute sulfuric acid as a catalyst for hydrolysis of Eucalyptus grandis residue. The purpose of this paper was to optimize the hydrolysis process in a 1.4 l pilot-scale reactor and investigate the effects of the acid concentration, temperature and residue/acid solution ratio on the hemicellulose removal and consequently on the production of sugars (xylose, glucose and arabinose) as well as on the formation of by-products (furfural, 5-hydroxymethylfurfural and acetic acid). This study was based on a model composition corresponding to a 2(3) orthogonal factorial design and employed the response surface methodology (RSM) to optimize the hydrolysis conditions, aiming to attain maximum xylose extraction from hemicellulose of residue. The considered optimum conditions were: H(2)SO(4) concentration of 0.65%, temperature of 157 degrees C and residue/acid solution ratio of 1/8.6 with a reaction time of 20 min. Under these conditions, 79.6% of the total xylose was removed and the hydrolysate contained 1.65 g/l glucose, 13.65 g/l xylose, 1.55 g/l arabinose, 3.10 g/l acetic acid, 1.23 g/l furfural and 0.20 g/l 5-hydroxymethylfurfural. PMID:16473004

  18. R76 in transmembrane domain 3 of the aspartate:alanine transporter AspT is involved in substrate transport.

    Science.gov (United States)

    Suzuki, Satomi; Nanatani, Kei; Abe, Keietsu

    2016-01-01

    The L-aspartate:L-alanine antiporter of Tetragenococcus halophilus (AspT) possesses an arginine residue (R76) within the GxxxG motif in the central part of transmembrane domain 3 (TM3)-a residue that has been estimated to transport function. In this study, we carried out amino acid substitutions of R76 and used proteoliposome reconstitution for analyzing the transport function of each substitution. Both l-aspartate and l-alanine transport assays showed that R76K has higher activity than the AspT-WT (R76), whereas R76D and R76E have lower activity than the AspT-WT. These results suggest that R76 is involved in AspT substrate transport. PMID:26849958

  19. Nanoparticle carriers based on copolymers of poly(l-aspartic acid co-l-lactide)-1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine for drug delivery

    Energy Technology Data Exchange (ETDEWEB)

    Han Siyuan; Wang Huan; Liang Xingjie [National Center for Nanoscience and Technology, Laboratory of Nanobiomedicine and Nanosafety, Division of Nanomedicine and Nanobiology (China); Hu Liming, E-mail: huliming@bjut.edu.cn [Beijing University of Technology, College of Life Science and Bioengineering (China); Li Min; Wu Yan, E-mail: wuy@nanoctr.cn [National Center for Nanoscience and Technology, Laboratory of Nanobiomedicine and Nanosafety, Division of Nanomedicine and Nanobiology (China)

    2011-09-15

    A novel poly(l-aspartic) derivative (PAL-DPPE) containing polylactide and 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE) segments has been successfully synthesized. The chemical structures of the copolymers were confirmed by Fourier-transform infrared spectroscopy (FTIR), NMR ({sup 1}H NMR, {sup 13}C NMR, {sup 31}P NMR), and thermogravimetric analysis (TGA). Fluorescence spectroscopy, dynamic light scattering (DLS), and transmission electron microscopy (TEM) confirmed the formation of micelles of the PAL-DPPE copolymers. In order to estimate the feasibility as novel drug carriers, an anti-tumor model drug doxorubicin (DOX) was incorporated into polymeric micelles by double emulsion and nanoprecipitation method. The DOX-loaded micelle size, size distribution, and encapsulation efficiency (EE) were influenced by the feed weight ratio of the copolymer to DOX. In addition, in vitro release experiments of the DOX-loaded PAL-DPPE micelles exhibited that faster release in pH 5.0 than their release in pH 7.4 buffer. The poly(l-aspartic) derivative copolymer was proved to be an available carrier for the preparation of micelles for anti-tumor drug delivery.

  20. Insulin aspart pharmacokinetics

    DEFF Research Database (Denmark)

    Rasmussen, Christian Hove; Roge, Rikke Meldgaard; Ma, Zhulin;

    2014-01-01

    Background: Insulin aspart (IAsp) is used by many diabetics as a meal-time insulin to control postprandial glucose levels. As is the case with many other insulin types, the pharmacokinetics (PK), and consequently the pharmacodynamics (PD), is associated with clinical variability, both between...... to investigate and quantify the properties of the subcutaneous depot. Data from Brange et al. (1990) are used to determine the effects of insulin chemistry in subcutis on the absorption rate. Intravenous (i.v.) bolus and infusion PK data for human insulin are used to understand and quantify the systemic...... distribution and elimination (Porksen et al., 1997; Sjostrand et al., 2002). PK and PD profiles for type 1 diabetics from Chen et al. (2005) are analyzed to demonstrate the effects of IAsp antibodies in terms of bound and unbound insulin. PK profiles from Thorisdottir et al. (2009) and Ma et al. (2012b...

  1. Amino acid residues in the CDC25 guanine nucleotide exchange factor critical for interaction with Ras.

    OpenAIRE

    Park, W.; Mosteller, R D; Broek, D.

    1994-01-01

    Previously we found that negatively charged residues at positions 62, 63, and 69 of H-Ras are involved in binding to the CDC25 guanine nucleotide exchange factor (GEF). Using site-directed mutagenesis, we have changed conserved, positively charged residues of CDC25GEF to glutamic acid. We find the nonfunctional CDC25R1374E mutant and the nonfunctional H-RasE63K mutant cooperate in suppression of the loss of CDC25 function in Saccharomyces cerevisiae. Also, peptides corresponding to residues 1...

  2. Identification of amino acid residues in Streptococcus mutans glucosyltransferases influencing the structure of the glucan product.

    Science.gov (United States)

    Shimamura, A; Nakano, Y J; Mukasa, H; Kuramitsu, H K

    1994-01-01

    The glucosyltransferases (GTFs) of mutans streptococci are important virulence factors in the sucrose-dependent colonization of tooth surfaces by these organisms. To investigate the structure-function relationship of the GTFs, an approach was initiated to identify amino acid residues of the GTFs which affect the incorporation of glucose residues into the glucan polymer. Conserved amino acid residues were identified in the GTF-S and GTF-I enzymes of the mutans streptococci and were selected for site-directed mutagenesis in the corresponding enzymes from Streptococcus mutans GS5. Conversion of six amino acid residues of the GTF-I enzyme to those present at the corresponding positions in GTF-S, either singly or in multiple combinations, resulted in enzymes synthesizing increased levels of soluble glucans. The enzyme containing six alterations synthesized 73% water-soluble glucan in the absence of acceptor dextran T10, while parental enzyme GTF-I synthesized no such glucan product. Conversely, when residue 589 of the GTF-S enzyme was converted from Thr to either Asp or Glu, the resulting enzyme synthesized primarily water-insoluble glucan in the absence of the acceptor. Therefore, this approach has identified several amino acid positions which influence the nature of the glucan product synthesized by GTFs. PMID:8050997

  3. Functional analyses of carnivorous plant-specific amino acid residues in S-like ribonucleases.

    Science.gov (United States)

    Arai, Naoki; Nishimura, Emi; Kikuchi, Yo; Ohyama, Takashi

    2015-09-11

    Unlike plants with no carnivory, carnivorous plants seem to use S-like ribonucleases (RNases) as an enzyme for carnivory. Carnivorous plant-specific conserved amino acid residues are present at four positions around the conserved active site (CAS). The roles of these conserved amino acid residues in the enzymatic function were explored in the current study by preparing five recombinant variants of DA-I, the S-like RNase of Drosera adelae. The kcat and kcat/Km values of the enzymes revealed that among the four variants with a single mutation, the serine to glycine mutation at position 111 most negatively influenced the enzymatic activity. The change in the bulkiness of the amino acid residue side-chain seemed to be the major cause of the above effect. Modeling of the three dimensional (3D) structures strongly suggested that the S to G mutation at 111 greatly altered the overall enzyme conformation. The conserved four amino acid residues are likely to function in keeping the two histidine residues, which are essential for the cleavage of RNA strands, and the CAS in the most functional enzymatic conformation. PMID:26235877

  4. Residual learning rates in lead-acid batteries: Effects on emerging technologies

    International Nuclear Information System (INIS)

    The low price of lead-acid, the most popular battery, is often used in setting cost targets for emerging energy storage technologies. Future cost reductions in lead acid batteries could increase investment and time scales needed for emerging storage technologies to reach cost-parity. In this paper the first documented model of cost reductions for lead-acid batteries is developed. Regression to a standard experience curve using 1989–2012 data yield a poor fit, with R2 values of 0.17 for small batteries and 0.05 for larger systems. To address this problem, battery costs are separated into material and residual costs, and experience curves developed for residual costs. Depending on the year, residual costs account for 41–86% of total battery cost. Using running-time averages to address volatility in material costs, a 4-year time average experience curve for residual costs yield much higher R2, 0.78 for small and 0.74 for large lead-acid batteries. The learning rate for residual costs in lead-acid batteries is 20%, a discovery with policy implications. Neglecting to consider cost reductions in lead-acid batteries could result in failure of energy storage start-ups and public policy programs. Generalizing this result, learning in incumbent technologies must be understood to assess the potential of emerging ones. -- Highlights: •We analyze potential cost reductions in lead-acid batteries. •Modified experience curve for non-material costs gives good empirical fit. •Historical learning rate for non-material costs from 1985–2012 is 19–24%. •Progress in incumbent technology raises barrier to new entrants

  5. Hybridization of glutamate aspartate transaminase. Investigation of subunit interaction.

    Science.gov (United States)

    Boettcher, B; Martinez-Carrion, M

    1975-10-01

    Glutamate aspartate transaminase (EC 2.6.1.1) is a dimeric enzyme with identical subunits with each active site containing pyridoxal 5'-phosphate linked via an internal Shiff's base to a lysine residue. It is not known if these sites interact during catalysis but negative cooperativity has been reported for binding of the coenzyme (Arrio-Dupont, M. (1972), Eur. J. Biochem. 30, 307). Also nonequivalence of its subunits in binding 8-anilinonaphthalene-1-sulfonate (Harris, H.E., and Bayley, P. M. (1975), Biochem. J. 145, 125), in modification of only a single tyrosine with full loss of activity (Christen, P., and Riordan, J.F. (1970), Biochemistry 9, 3025), and following modification with 5,5'-dithiobis(2-nitrobenzoic acid) (Cournil, I., and Arrio-Dupont, M. (1973), Biochemie 55, 103) has been reported. However, steady-state and transient kinetic methods as well as direct titration of the active site chromophore with substrates and substrate analogs have not revealed any cooperative phenomena (Braunstein, A. E. (1973), Enzymes, 3rd Ed. 9, 379). It was therefore decided that a more direct approach should be used to clarify the quistion of subunit interaction during the covalent phase of catalysis. To this end a hybrid method was devised in which a hybrid transaminase was prepared which contained one subunit with a functional active site while the other subunit has the internal Shiff's base reduced with NaBH4. The specific activities and amount of "actively bound" pyridoxal 5'-phosphate are both in a 2:1 ratio for the native and hybrid forms. Comparison of the steady-state kinetic properties of the hybrid and native enzyme forms shows that both forms gave parallel double reciprocal plots which is characteristic of the Ping-Pong Bi-Bi mechanism of transamination. The Km values for the substrates L-aspartic acid and alpha-ketoglutaric acid are nearly identical while the Vmax value for the hybrid is one-half the value of the native transaminase. It therefore appears that

  6. Substitution at aspartic acid 1128 in the SARS coronavirus spike glycoprotein mediates escape from a S2 domain-targeting neutralizing monoclonal antibody.

    Directory of Open Access Journals (Sweden)

    Oi-Wing Ng

    Full Text Available The Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV is the etiological agent for the infectious disease, SARS, which first emerged 10 years ago. SARS-CoV is a zoonotic virus that has crossed the species barriers to infect humans. Bats, which harbour a diverse pool of SARS-like CoVs (SL-CoVs, are believed to be the natural reservoir. The SARS-CoV surface Spike (S protein is a major antigenic determinant in eliciting neutralizing antibody production during SARS-CoV infection. In our previous work, we showed that a panel of murine monoclonal antibodies (mAbs that target the S2 subunit of the S protein are capable of neutralizing SARS-CoV infection in vitro (Lip KM et al, J Virol. 2006 Jan; 80(2: 941-50. In this study, we report our findings on the characterization of one of these mAbs, known as 1A9, which binds to the S protein at a novel epitope within the S2 subunit at amino acids 1111-1130. MAb 1A9 is a broadly neutralizing mAb that prevents viral entry mediated by the S proteins of human and civet SARS-CoVs as well as bat SL-CoVs. By generating mutant SARS-CoV that escapes the neutralization by mAb 1A9, the residue D1128 in S was found to be crucial for its interaction with mAb 1A9. S protein containing the substitution of D1128 with alanine (D1128A exhibited a significant decrease in binding capability to mAb 1A9 compared to wild-type S protein. By using a pseudotyped viral entry assay, it was shown that the D1128A substitution in the escape virus allows it to overcome the viral entry blockage by mAb 1A9. In addition, the D1128A mutation was found to exert no effects on the S protein cell surface expression and incorporation into virion particles, suggesting that the escape virus retains the same viral entry property as the wild-type virus.

  7. Synthesis of an Ursolic Acid Saponin with N-Acetylglucosamine-containing Trisaccharide Residue

    Institute of Scientific and Technical Information of China (English)

    WANG Peng; LI Chun-Xia; WANG Guang-Fa; LI Ying-Xia

    2006-01-01

    The focus of this work is the synthesis of an ursolic acid saponin with an N-acetylglucosamine-containing trisaccharide residue. Therefore, ursolic acid 3-yl α-L-arabinopyranosyl-(1→2)-α-L-arabinopyranosyl-(1→6)-2-acetamido-2-deoxy-β-D-glucopyranoside (1) was concisely synthesized in convergent synthesis with 48.0% overall yield. The structure of saponin 1 was confirmed by 1H NMR, 13C NMR and mass spectra.

  8. Isoelectric Point, Electric Charge, and Nomenclature of the Acid-Base Residues of Proteins

    Science.gov (United States)

    Maldonado, Andres A.; Ribeiro, Joao M.; Sillero, Antonio

    2010-01-01

    The main object of this work is to present the pedagogical usefulness of the theoretical methods, developed in this laboratory, for the determination of the isoelectric point (pI) and the net electric charge of proteins together with some comments on the naming of the acid-base residues of proteins. (Contains 8 figures and 4 tables.)

  9. Synthesis and Crystal Structure of a New Ternary Complex of Nickel(Ⅱ) with L-Aspartic Acid and 1,10-Phenanthroline

    Institute of Scientific and Technical Information of China (English)

    马录芳; 梁福沛; 覃海错; 胡瑞祥; 张漫波

    2004-01-01

    A new ternary complex of nickel(Ⅱ) with L-aspartate (L-Asp) and 1, 10-phenanthroline(Phen), [Ni3(L-Asp)(Phen)5(H2O)3](ClO4)4.4.75H2O, has been synthesized in a mixed solvent of H2OC2H5OH at the pH value of 3. It crystallizes in triclinic, space group P-1 with a =11.861(2), b = 18.384(4), c = 19.746(3)(°A), α = 107.68(1), β = 105.94(1), γ= 103.41(2)°, V =3703.6(11) (°A)3, Mr = 1745.66, Z = 2, Dc =1.565 g/cm3, u = 0.989 mm-1, F(000) = 1791, R = 0.0643and wR = 0.1611. The complex contains two cations, binuclear [Ni2(L-Asp)(Phen)3(H2O)]2+ and mononu- clear [Ni(Phen)2(H2O)2]2+. All the nickel ions in the complex are six-coordinated with a distorted octahedral geometry, but the coordination environments for them are different. There exist hydrogen bonds and π-π stacking interactions in the complex.

  10. Process optimization of reaction of acid leaching residue of asbestos tailing and sodium hydroxide aqueous solution

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Silica is the major component of the acid leaching residue of asbestos tailing. The waterglass solution can be prepared by the reaction of the residue with sodium hydroxide aqueous solution. Compared to the high temperature reaction method, this process is environmental friendly and low cost. In this paper, the reaction process of the residue and the sodium hydroxide aqueous solution is optimized. The optimum reaction process parameters are as follows: the usage of sodium hydroxide is 26.4 g/100 g acid leaching residue, the reaction temperature is 90℃, the reaction time is 1 h, and the ratio of the liquid/solid is 2.0. The significance sequence of the process parameters to the alkali leaching reaction effect is the usage of sodium hydroxide > the ratio of the liquid/solid > the reaction time > the reaction temperature. The significance sequence to the leaching ratio of SiO2 is the ratio of the liquid/solid > the usage of sodium hydroxide > the reaction time > the reaction temperature. The significance sequence to the modulus of the sodium silicate is the ratio of the liquid/solid > the usage of sodium hydroxide > the reaction time > the reaction temperature. Under the optimum conditions, the leaching ratio of the SiO2 is 77.5%, and the modulus of the sodium silicate is 3.15. The XRD analysis result indicates that the major components of the alkali leaching residue are serpentine, talc, quartz and some albite.

  11. Characteristics of lactic acid bacteria isolates and their effect on silage fermentation of fruit residues.

    Science.gov (United States)

    Yang, Jinsong; Tan, Haisheng; Cai, Yimin

    2016-07-01

    The natural lactic acid bacteria (LAB) population, chemical composition, and silage fermentation of fruit residues were studied. Eighty-two strains of LAB were isolated from fruit residues such as banana leaf and stem, pineapple peel, and papaya peel. All strains were gram-positive and catalase-negative bacteria, and they were divided into 7 groups (A-G) according to morphological and biochemical characters. Strains in groups A to F were rods, and group G was cocci. Group F produced gas from glucose; other groups did not. Groups A to C and F formed dl-lactic acid, whereas groups D, E, and G formed l-lactic acid. Based on the 16S rRNA gene sequence and DNA-DNA hybridization analysis, groups A to G strains were identified as Lactobacillus plantarum (54.9% of the total isolates), Lactobacillus paraplantarum (3.6%), Lactobacillus nagelii (8.5%), Lactobacillus perolens (4.9%), Lactobacillus casei (11.0%), Lactobacillus fermentum (9.8%), and Enterococcus gallinarum (7.3%), respectively. Lactobacillus plantarum and Lactobacillus casei are the most frequently isolated from fruit residues as a dominant species, and they could grow at a lower pH conditions and produce more lactic acid than other isolates. Pineapple and papaya peels contained higher crude protein (11.5-13.8%) and water-soluble carbohydrate (16.8-22.4%), but lower acid detergent fiber contents (21.2 to 26.4%) than banana stems and leaves (8.2% crude protein, 42.8% acid detergent fiber, and 5.1% water-soluble carbohydrate). Compared with banana stem and leaf silages, the pineapple and papaya peel silages were well preserved with a lower pH and higher lactate content. The study suggests that the fruit residues contain excellent LAB species and abundant feed nutrients, and that they can be preserved as silage to be potential food resources for livestock.

  12. Characteristics of lactic acid bacteria isolates and their effect on silage fermentation of fruit residues.

    Science.gov (United States)

    Yang, Jinsong; Tan, Haisheng; Cai, Yimin

    2016-07-01

    The natural lactic acid bacteria (LAB) population, chemical composition, and silage fermentation of fruit residues were studied. Eighty-two strains of LAB were isolated from fruit residues such as banana leaf and stem, pineapple peel, and papaya peel. All strains were gram-positive and catalase-negative bacteria, and they were divided into 7 groups (A-G) according to morphological and biochemical characters. Strains in groups A to F were rods, and group G was cocci. Group F produced gas from glucose; other groups did not. Groups A to C and F formed dl-lactic acid, whereas groups D, E, and G formed l-lactic acid. Based on the 16S rRNA gene sequence and DNA-DNA hybridization analysis, groups A to G strains were identified as Lactobacillus plantarum (54.9% of the total isolates), Lactobacillus paraplantarum (3.6%), Lactobacillus nagelii (8.5%), Lactobacillus perolens (4.9%), Lactobacillus casei (11.0%), Lactobacillus fermentum (9.8%), and Enterococcus gallinarum (7.3%), respectively. Lactobacillus plantarum and Lactobacillus casei are the most frequently isolated from fruit residues as a dominant species, and they could grow at a lower pH conditions and produce more lactic acid than other isolates. Pineapple and papaya peels contained higher crude protein (11.5-13.8%) and water-soluble carbohydrate (16.8-22.4%), but lower acid detergent fiber contents (21.2 to 26.4%) than banana stems and leaves (8.2% crude protein, 42.8% acid detergent fiber, and 5.1% water-soluble carbohydrate). Compared with banana stem and leaf silages, the pineapple and papaya peel silages were well preserved with a lower pH and higher lactate content. The study suggests that the fruit residues contain excellent LAB species and abundant feed nutrients, and that they can be preserved as silage to be potential food resources for livestock. PMID:27108171

  13. Physicochemical pretreatments and hydrolysis of furfural residues via carbon-based sulfonated solid acid.

    Science.gov (United States)

    Ma, Bao Jun; Sun, Yuan; Lin, Ke Ying; Li, Bing; Liu, Wan Yi

    2014-03-01

    Potential commercial physicochemical pretreatment methods, NaOH/microwave and NaOH/ultrasound were developed, and the carbon-based sulfonated solid acid catalysts were prepared for furfural residues conversion into reducing sugars. After the two optimum pretreatments, both the content of cellulose increased (74.03%, 72.28%, respectively) and the content of hemicellulose (94.11%, 94.17% of removal rate, respectively) and lignin (91.75%, 92.09% of removal rate, respectively) decreased in furfural residues. The reducing sugar yields of furfural residues with the two physicochemical pretreatments on coal tar-based solid acid reached 33.94% and 33.13%, respectively, higher than that pretreated via NaOH alone (27%) and comparable to that pretreated via NaOH/H2O2 (35.67%). The XRD patterns, IR spectra and SEM images show microwave and ultrasound improve the pretreatment effect. The results demonstrate the carbon-based sulfonated solid acids and the physicochemical pretreatments are green, effective, low-cost for furfural residues conversion.

  14. Effect of Dodecylbenzene Sulfonic Acid Used as Additive on Residue Hydrotreating

    Institute of Scientific and Technical Information of China (English)

    Sun Yudong; Yang Chaohe

    2015-01-01

    The effect of additive—dodecylbenzene sulfonic acid (DBSA)—on residue hydrotreating was studied in the au-toclave. The results showed that the additive improved stabilization of the colloid system of residue, which could delay the aggregation and coke formation from asphaltenes on the catalyst, and make heavy components transformed into light oil. The residue conversion in the presence of this additive increased by 1.94%, and the yield of light oil increased by 1.53% when the reaction time was 90 min. The surface properties of the catalyst in the presence of this additive were better than that of the blank test within a very short time (30 min) and deteriorated rapidly after a longer reaction time due to higher conversion and coke deposition. Compared with the blank test, the case using the said additive had shown that the structure of hydrotreated asphaltene units was smaller and the condensation degrees were higher. The test results indicated that the additive could improve the hydrotreating reactivity of residue via permeation and depolymerization, the heavier components could be transformed into light oil more easily, and the light oil yield and residue conversion were higher for the case using the said additive in residue hydrotreating process.

  15. Identification of the amino acid residues rendering TI-VAMP insensitive toward botulinum neurotoxin B.

    Science.gov (United States)

    Sikorra, Stefan; Henke, Tina; Swaminathan, Subramanyam; Galli, Thierry; Binz, Thomas

    2006-03-24

    Botulinum neurotoxins types B, D, F, and G, and tetanus neurotoxin inhibit vesicular fusion via proteolytic cleavage of VAMP/Synaptobrevin, a core component of the membrane fusion machinery. Thus, these neurotoxins became widely used tools for investigating vesicular trafficking routes. Except for VAMP-1, VAMP-2, and Cellubrevin, no other member of the VAMP family represents a substrate for these neurotoxins. The molecular basis for this discrepancy is not known. A 34 amino acid residue segment of VAMP-2 was previously suggested to mediate the interaction with botulinum neurotoxin B, but the validity of the data was later questioned. To check whether this segment alone controls the susceptibility toward botulinum neurotoxin B, it was used to replace the corresponding segment in TI-VAMP. The resulting VAMP hybrid and VAMP-2 were hydrolysed at virtually identical rates. Resetting the VAMP-2 portion in the hybrid from either end to TI-VAMP residues gradually reduced the cleavability. A hybrid encompassing merely the VAMP-2 segment 71-80 around the Gln76/Phe77 scissile bond was still hydrolysed, albeit at a approximately tenfold lower cleavage rate. The contribution of each non-conserved amino acid of the whole 34-mer segment to the interaction was investigated employing VAMP-2. We find that the eight non-conserved residues of the 71-80 segment are all necessary for efficient cleavage. Mutation of an additional six residues located upstream and downstream of this segment affects substrate hydrolysis as well. Vice versa, a readily cleavable TI-VAMP molecule requires at the least the replacement of Ile158, Thr161, and the section 165-174 by Asp64, Ala67, and the 71-80 segment of VAMP-2, respectively. However, the insensitivity of TI-VAMP to botulinum neurotoxin B relies on at least 12 amino acid changes versus VAMP-2. These are scattered along an interface of 22 amino acid residues in length.

  16. Critical Amino Acid Residues for Nicotine 5' -Hydroxylation in Human CYP2A Enzymes

    Institute of Scientific and Technical Information of China (English)

    Xiaoyang He Xiaoyang He; Xu Xu; Jian Shen; Li Sun; Anthony Y. H. Lu; Clifford Weisel; Junyan Hong

    2008-01-01

    Objective: We have continued previous work in which we demonstrated that #117 and #372 amino acids contrib-uted to the high activities of human CYP2A13 in catalyzing 4-methylnitrosamino-1-(3-pyridyl)-1-hutanone(NNK) and aflatoxin B1(AFB1) carcinogenic activation. The present study was designed to identify other potential amino acid residues that contribute to the different catalytic characteristics of two CYP2A enzymes, CYP2A6 and CYP2A13, in nicotine metabolism and provide insights of the substrate and related amino acid residues interactions. Methods: A series of reciprocally substituted mutants of CYP2A6IIe'300→Phe, CYP2A6Gly'301Ala, CYP2A6Ser'369→Gly, CYP2A13Phe'300→Ile, CYP2A13AIa'301→Gly and CYP2A13Gly'369→Ser were generated by site-directed mutagenesis/baculovirus-Sf9 insect cells expression. Comparative kinetic analysis of nicotine 5'hydroxylatin by wild type and mutant CYP2A proteins was performed. Results:All amino acid residue substitutions at 300, 301 and 369 caused significant kinetic property changes in nicotine metabolism. While CYP2A6Ile'300→Phe and CYP2A6Gly'301→Ala mutations had notable catalytic efficiency increases compared to that for the wild type CYP2A6, CYP2A13Phe'300→Ile and CYP2A13Ala'301→Gly replacement introduced remarkable catalytic efficiency decreases. In addition, all these catalytic efficiency alterations were caused by V,maxvariations rather than K,m changes. Substi-tution of #369 residue significantly affected both K,m and V,max values. CYP2A6Ser'369→Gly increase the catalytic efficiency via a significant Km decrease versus V,max enhancement, while the opposite effects were seen with CYP2A13Gly'369→Ser. Conclusion:#300, #301 and #369 residues in human CYP2A6/13 play important roles in nicotine 5' -oxidation. Switching #300 or #301 residues did not affect the CYP2A protein affinities toward nicotine, although these amino acids are located in the active center. Seta69 to Gly substitution indirectly affected

  17. A novel sono-assisted acid pretreatment of chili post harvest residue for bioethanol production.

    Science.gov (United States)

    Sindhu, Raveendran; Binod, Parameswaran; Pandey, Ashok

    2016-08-01

    The objective of the present study was to develop a sono-assisted acid pretreatment strategy for the effective removal of lignin and hemicelluloses and to improve the sugar yield from chili post harvest residue. Operational parameters that affect the pretreatment efficiency were studied and optimized. Inhibitor analysis of the hydrolyzate revealed that major fermentation inhibitors like furfural, hydroxymethyl furfural and organic acids like citric acid, succinic acid and propionic acid were absent. Changes in structural properties of the biomass were studied in relation to the pretreatment process using scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier Transform Infrared (FTIR) analysis, and the changes in chemical composition was also monitored. The biomass pretreated with the optimized novel method yielded 0.465g/g of reducing sugars on enzymatic hydrolysis. Fermentation of the non-detoxified hydrolysate yielded 2.14% of bioethanol with a fermentation efficiency of 71.03%. PMID:26949055

  18. In vivo simultaneous monitoring of gamma-aminobutyric acid, glutamate, and L-aspartate using brain microdialysis and capillary electrophoresis with laser-induced fluorescence detection: Analytical developments and in vitro/in vivo validations.

    Science.gov (United States)

    Sauvinet, Valérie; Parrot, Sandrine; Benturquia, Nadia; Bravo-Moratón, Eva; Renaud, Bernard; Denoroy, Luc

    2003-09-01

    gamma-Aminobutyric acid (GABA), glutamate (Glu), and L-aspartate (L-Asp) are three major amino acid neurotransmitters in the central nervous system. In this work, a method for the separation of these three neurotransmitters in brain microdialysis samples using a commercially available capillary electrophoresis (CE) system has been developed. Molecules were tagged on their primary amine function with the fluorogene agent naphthalene-2,3-dicarboxaldehyde (NDA), and, after separation by micellar electrokinetic chromatography, were detected by laser-induced fluorescence using a 442 nm helium-cadmium laser. The separation conditions for the analysis of derivatized neurotransmitters in standard solutions and microdialysates have been optimized, and this method has been validated on both pharmacological and analytical basis. The separation of GABA, Glu, and L-Asp takes less than 10 min by using a 75 mmol/L borate buffer, pH 9.2, containing 70 mmol/L SDS and 10 mmol/L hydroxypropyl-beta-cyclodextrin and + 25 kV voltage. The detection limits were 3, 15 nmol/L and, 5 nmol/L for GABA, Glu, and L-Asp, respectively. Moreover, submicroliter samples can be analyzed. This method allows a simple, rapid and accurate measurement of the three amino acid neurotransmitters for the in vivo brain monitoring using microdialysis sampling.

  19. Preparation and Inhibition Performance of Aspartic Acid Intercalated ZnAl Layered Double Hydroxides%天冬氨酸插层ZnAl双金属氢氧化物的制备及其对铜的缓蚀性能研究

    Institute of Scientific and Technical Information of China (English)

    全贞兰; 张冬梅; 侯万国

    2011-01-01

    Aspartic acids (Asp) were intercalated into ZnAl layered double hydroxides(ZnAlLDHs) by ion exchange method. The products were characterized by powder X-ray diffration (PXRD) and fourier transform infrared spectroscopy (FTIR). The results showed that Asp-LDHs nanohybrids were formed by the intercalation of the aspartic acid into the ZnAl layered double hydroxides. The nanohybrids were deposited on copper by colloid deposition method, and the quality and protection performance of the resulted film against corrosion were evaluated by electrochemical impedance spectroscopy (EIS) and polarization curves. All the results demonstrated that aspartic acid intercalated Zn-Al LDHs could inhibit the corrosion of copper effectively.%以锌铝层状双金属氢氧化物(LDHs)为主体,夭冬氨酸(aspartic acid,Asp)为客体,采用离子交换法合成了Asp-LDHs杂化物.粉末X射线衍射(PXRD)和傅里叶变换红外光谱(FTIR)分析结果表明,天冬氨酸成功插入LDHs层间,形成杂化物.用胶体沉积技术将杂化物沉积在铜基底上,电化学阻抗谱(EIS)和极化曲线研究表明,Asp-LDHs杂化物薄膜对铜具有良好的缓蚀作用.

  20. Comparison between liquid and solid acids catalysts on reducing sugars conversion from furfural residues via pretreatments.

    Science.gov (United States)

    Lin, Keying; Ma, Baojun; Sun, Yuan; Liu, Wanyi

    2014-09-01

    Liquid sulphuric acid is adopted and compared with carbon-based sulfonated solid acids (coal tar-based and active carbon-based) for furfural residues conversion into reducing sugars. The optimum hydrolysis conditions of liquid acid are at 4% of sulphuric acid, 25:1 of liquid and solid ratio, 175°C of reaction temperature and 120 min of reaction time. The reducing sugar yields are reached over 60% on liquid acid via NaOH/H2O2, NaOH/microwave and NaOH/ultrasonic pretreatments, whereas only over 30% on solid acids. The TOFs (turnover number frequency) via NaOH/H2O2 pretreatments are 0.093, 0.020 and 0.023 h(-1) for liquid sulphuric acid, coal tar-based and active carbon-based solid acids catalysts, respectively. Considering the efficiency, cost and environment factors, the liquid and solid acids have their own advantages of potential commercial application values.

  1. Acid leaching of uranium present in a residue from mining industry

    Energy Technology Data Exchange (ETDEWEB)

    Braulio, Walace S.; Ladeira, Ana C.Q. [Center for Development of Nuclear Technology (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil). Dept. of Mineral Technology

    2011-07-01

    The acid mine drainage is one of the most important environmental problems associated with mining of ores containing sulfides. The treatment of these acid effluents, which contains high concentrations of dissolved metals and anions, is generally by liming. The wastes generated in the liming process may present significant toxicity and their storage in inappropriate places waiting for treatment is a common issue that requires solution. Osamu Utsumi Mine located in the city of Caldas, Minas Gerais, has been facing this problem. The residue of this mine consists of an alkaline sludge generated from the neutralization of the pH of acid mine drainage and is rich in various metals, including uranium. The main concern is the long term stability of this residue, which is in permanent contact with the acid water in the open pit. The recovery of uranium by hydrometallurgical techniques, such as acid leaching, can be a viable alternative on the reuse of this material. This study aimed at establishing a specific leaching process for the recovery of uranium present in the sludge from Caldas uranium mine. Some parameters such as solid/liquid ratio (0.09 to 0.17), time of leaching (1 to 24 hours) and concentration of sulfuric acid (pH from 0 to 3.0) were assessed. The results showed that it is possible to extract 100% of uranium present in the sludge. The concentration of U{sub 3}O{sub 8} in the residue was 0.25%, similar to the content of the vein ores which is around 0.20% to 1.0%. The best experimental leaching condition is solid/liquid ratio of 0.17, pH 1.0 and 2 hours of reaction at room temperature (25 deg C). The content of uranium in the liquor is around 440 mgL{sup -1}. The recovery of the uranium from the liquor is under investigation by ionic exchange. (author)

  2. Vesicular uptake and exocytosis of l-aspartate is independent of sialin

    Science.gov (United States)

    Morland, Cecilie; Nordengen, Kaja; Larsson, Max; Prolo, Laura M.; Farzampour, Zoya; Reimer, Richard J.; Gundersen, Vidar

    2013-01-01

    The mechanism of release and the role of l-aspartate as a central neurotransmitter are controversial. A vesicular release mechanism for l-aspartate has been difficult to prove, as no vesicular l-aspartate transporter was identified until it was found that sialin could transport l-aspartate and l-glutamate when reconstituted into liposomes. We sought to clarify the release mechanism of l-aspartate and the role of sialin in this process by combining l-aspartate uptake studies in isolated synaptic vesicles with immunocyotchemical investigations of hippocampal slices. We found that radiolabeled l-aspartate was taken up into synaptic vesicles. The vesicular l-aspartate uptake, relative to the l-glutamate uptake, was twice as high in the hippocampus as in the whole brain, the striatum, and the entorhinal and frontal cortices and was not inhibited by l-glutamate. We further show that sialin is not essential for exocytosis of l-aspartate, as there was no difference in ATP-dependent l-aspartate uptake in synaptic vesicles from sialin-knockout and wild-type mice. In addition, expression of sialin in PC12 cells did not result in significant vesicle uptake of l-aspartate, and depolarization-induced depletion of l-aspartate from hippocampal nerve terminals was similar in hippocampal slices from sialin-knockout and wild-type mice. Further, there was no evidence for nonvesicular release of l-aspartate via volume-regulated anion channels or plasma membrane excitatory amino acid transporters. This suggests that l-aspartate is exocytotically released from nerve terminals after vesicular accumulation by a transporter other than sialin.—Morland, C., Nordengen, K., Larsson, M., Prolo, L. M., Farzampour, Z., Reimer, R. J., Gundersen, V. Vesicular uptake and exocytosis of l-aspartate is independent of sialin. PMID:23221336

  3. A method for computing the inter-residue interaction potentials for reduced amino acid alphabet

    Indian Academy of Sciences (India)

    Abhinav Luthra; Anupam Nath Jha; G K Ananthasuresh; Saraswathi Vishveswara

    2007-08-01

    Inter-residue potentials are extensively used in the design and evaluation of protein structures. However, dealing with all (20×20) interactions becomes computationally difficult in extensive investigations. Hence, it is desirable to reduce the alphabet of 20 amino acids to a smaller number. Currently, several methods of reducing the residue types exist; however a critical assessment of these methods is not available. Towards this goal, here we review and evaluate different methods by comparing with the complete (20×20) matrix of Miyazawa-Jernigan potential, including a method of grouping adopted by us, based on multi dimensional scaling (MDS). The second goal of this paper is the computation of inter-residue interaction energies for the reduced amino acid alphabet, which has not been explicitly addressed in the literature until now. By using a least squares technique, we present a systematic method of obtaining the interaction energy values for any type of grouping scheme that reduces the amino acid alphabet. This can be valuable in designing the protein structures.

  4. Process optimization of reaction of acid leaching residue of asbestos tailing and sodium hydroxide aqueous solution

    Institute of Scientific and Technical Information of China (English)

    DU GaoXiang; ZHENG ShuiLin; DING Hao

    2009-01-01

    Silica is the major component of the acid leaching residue of asbestos tailing. The waterglass solution can be prepared by the reaction of the residue with sodium hydroxide aqueous solution. Compared to the high temperature reaction method, this process is environmental friendly and low cost. In this paper, the reaction process of the residue and the sodium hydroxide aqueous solution is optimized. The op-timum reaction process parameters are as follows: the usage of sodium hydroxide is 26.4 g/100 g acid leaching residue, the reaction temperature is 90℃, the reaction time is 1 h, and the ratio of the liq-uid/solid is 2.0. The significance sequence of the process parameters to the alkali leaching reaction effect is the usage of sodium hydroxide > the ratio of the liquid/solid > the reaction time > the reaction temperature. The significance sequence to the leaching ratio of SiO2 is the ratio of the liquid/solid > the usage of sodium hydroxide > the reaction time > the reaction temperature. The significance sequence to the modulus of the sodium silicate is the ratio of the liquid/solid > the usage of sodium hydroxide > the reaction time > the reaction temperature. Under the optimum conditions, the leaching ratio of the SiO2 is 77.5%, and the modulus of the sodium silicate is 3.15. The XRD analysis result indicates that the major components of the alkali leaching residue are serpentine, talc, quartz and some albite.

  5. 聚(乳酸-天冬氨酸)的合成及性能研究%The Synthesis and Property Study of the Poly(Lactide-alt-Aspartic Acid)

    Institute of Scientific and Technical Information of China (English)

    余飞; 刘文明

    2013-01-01

    3-[(benzyloxycarbonyl) methyl] morpholine-2,5-dione (MMD) was synthesized via aspartic acid and chloroacetyl chloride as the raw materials.Afterwards,poly(lactide-alt-aspartic acid) was obtained by copolymerizing lactide and MMD of which structure was confirmed by FTIR,1 H-NMR.Effects of catalyst amount,polymerization time and temperature on the inherent viscosity of the product were studied.In addition,the water absorption and degradation between this copolymer and PLA were investigated.It was revealed that at 160 ℃ for 8 h,with 0.3% (wt) catalyst amount of the total reactants,co-polymer with the highest inherent viscosity can be achieved.The synthesized copolymer in this paper had improved water absorption and weight loss rate in comparison with PLA.%以天冬氨酸和氯乙酰氯为原料合成了3-[(苄氧羰基)-甲基]-吗啉-2,5-二酮,再与丙交酯共聚合成聚(乳酸-天冬氨酸),并用FTIR、1H NMR对其进行结构表征.研究了3-[(苄氧羰基)-甲基]-吗啉-2,5-二酮与丙交酯的共聚反应,探讨了不同催化剂用量、聚合时间、聚合温度对聚合物特性黏数的影响;并对共聚物与PLA的亲水性以及降解性能进行了对比.结果表明,催化剂用量为反应物质量的0.3%,聚合时间8h,聚合温度160℃时,共聚物的特性黏数最大;改性后的聚乳酸亲水性能、降解性能都优于聚乳酸.

  6. Biochemical Roles for Conserved Residues in the Bacterial Fatty Acid-binding Protein Family.

    Science.gov (United States)

    Broussard, Tyler C; Miller, Darcie J; Jackson, Pamela; Nourse, Amanda; White, Stephen W; Rock, Charles O

    2016-03-18

    Fatty acid kinase (Fak) is a ubiquitous Gram-positive bacterial enzyme consisting of an ATP-binding protein (FakA) that phosphorylates the fatty acid bound to FakB. In Staphylococcus aureus, Fak is a global regulator of virulence factor transcription and is essential for the activation of exogenous fatty acids for incorporation into phospholipids. The 1.2-Å x-ray structure of S. aureus FakB2, activity assays, solution studies, site-directed mutagenesis, and in vivo complementation were used to define the functions of the five conserved residues that define the FakB protein family (Pfam02645). The fatty acid tail is buried within the protein, and the exposed carboxyl group is bound by a Ser-93-fatty acid carboxyl-Thr-61-His-266 hydrogen bond network. The guanidinium of the invariant Arg-170 is positioned to potentially interact with a bound acylphosphate. The reduced thermal denaturation temperatures of the T61A, S93A, and H266A FakB2 mutants illustrate the importance of the hydrogen bond network in protein stability. The FakB2 T61A, S93A, and H266A mutants are 1000-fold less active in the Fak assay, and the R170A mutant is completely inactive. All FakB2 mutants form FakA(FakB2)2 complexes except FakB2(R202A), which is deficient in FakA binding. Allelic replacement shows that strains expressing FakB2 mutants are defective in fatty acid incorporation into phospholipids and virulence gene transcription. These conserved residues are likely to perform the same critical functions in all bacterial fatty acid-binding proteins.

  7. Acid hydrolysis of Curcuma longa residue for ethanol and lactic acid fermentation.

    Science.gov (United States)

    Nguyen, Cuong Mai; Nguyen, Thanh Ngoc; Choi, Gyung Ja; Choi, Yong Ho; Jang, Kyoung Soo; Park, Youn-Je; Kim, Jin-Cheol

    2014-01-01

    This research examines the acid hydrolysis of Curcuma longa waste, to obtain the hydrolysate containing lactic acid and ethanol fermentative sugars. A central composite design for describing regression equations of variables was used. The selected optimum condition was 4.91% sulphuric acid, 122.68°C and 50 min using the desirability function under the following conditions: the maximum reducing sugar (RS) yield is within the limited range of the 5-hydroxymethylfurfural (HMF) and furfural concentrations. Under the condition, the obtained solution contained 144 g RS/L, 0.79 g furfural/L and 2.59 g HMF/L and was directly fermented without a detoxification step. The maximum product concentration, average productivity, RS conversion and product yield were 115.36 g/L, 2.88 g/L/h, 89.43% and 64% for L-lactic acid; 113.92 g/L, 2.59 g/L/h, 88.31% and 63.29% for D-lactic acid; and 55.03 g/L, 1.38 g/L/h, 42.66 and 30.57%, respectively, for ethanol using a 7-L jar fermenter.

  8. Acid hydrolysis of Curcuma longa residue for ethanol and lactic acid fermentation.

    Science.gov (United States)

    Nguyen, Cuong Mai; Nguyen, Thanh Ngoc; Choi, Gyung Ja; Choi, Yong Ho; Jang, Kyoung Soo; Park, Youn-Je; Kim, Jin-Cheol

    2014-01-01

    This research examines the acid hydrolysis of Curcuma longa waste, to obtain the hydrolysate containing lactic acid and ethanol fermentative sugars. A central composite design for describing regression equations of variables was used. The selected optimum condition was 4.91% sulphuric acid, 122.68°C and 50 min using the desirability function under the following conditions: the maximum reducing sugar (RS) yield is within the limited range of the 5-hydroxymethylfurfural (HMF) and furfural concentrations. Under the condition, the obtained solution contained 144 g RS/L, 0.79 g furfural/L and 2.59 g HMF/L and was directly fermented without a detoxification step. The maximum product concentration, average productivity, RS conversion and product yield were 115.36 g/L, 2.88 g/L/h, 89.43% and 64% for L-lactic acid; 113.92 g/L, 2.59 g/L/h, 88.31% and 63.29% for D-lactic acid; and 55.03 g/L, 1.38 g/L/h, 42.66 and 30.57%, respectively, for ethanol using a 7-L jar fermenter. PMID:24240182

  9. Composition, texture and methane potential of cellulosic residues from Lewis acids organosolv pulping of wheat straw.

    Science.gov (United States)

    Constant, Sandra; Barakat, Abdellatif; Robitzer, Mike; Di Renzo, Francesco; Dumas, Claire; Quignard, Françoise

    2016-09-01

    Cellulosic pulps have been successfully isolated from wheat straw through a Lewis acids organosolv treatment. The use of Lewis acids with different hardness produced pulps with different delignification degrees. The cellulosic residue was characterised by chemical composition, X-ray diffraction, FT-IR spectroscopy, N2 physisorption, scanning electron microscopy and potential for anaerobic digestibility. Surface area and pore volume increased with the hardness of the Lewis acid, in correspondence with the decrease of the amount of lignin and hemicellulose in the pulp. The non linearity of the correlation between porosity and composition suggests that an agglomeration of cellulose fibrils occurs in the early stages of pulping. All organosolv pulps presented a significantly higher methane potential than the parent straw. A methane evolution of 295Ncm(3)/g OM was reached by a moderate improvement of the accessibility of the native straw. PMID:27295251

  10. Leaching of lead from zinc leach residue in acidic calcium chloride aqueous solution

    Science.gov (United States)

    Wang, Le; Mu, Wen-ning; Shen, Hong-tao; Liu, Shao-ming; Zhai, Yu-chun

    2015-05-01

    A process with potentially reduced environmental impacts and occupational hazards of lead-bearing zinc plant residue was studied to achieve a higher recovery of lead via a cost-effective and environmentally friendly process. This paper describes an optimization study on the leaching of lead from zinc leach residue using acidic calcium chloride aqueous solution. Six main process conditions, i.e., the solution pH value, stirring rate, concentration of CaCl2 aqueous solution, liquid-to-solid (L/S) ratio, leaching temperature, and leaching time, were investigated. The microstructure and components of the residue and tailing were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD). On the basis of experimental results, the optimum reaction conditions were determined to be a solution pH value of 1, a stirring rate of 500 r·min-1, a CaCl2 aqueous solution concentration of 400 g·L-1, a liquid-to-solid mass ratio of 7:1, a leaching temperature of 80°C, and a leaching time of 45 min. The leaching rate of lead under these conditions reached 93.79%, with an iron dissolution rate of 19.28%. Silica did not take part in the chemical reaction during the leaching process and was accumulated in the residue.

  11. [Determination of clavulanic acid residue in milk by high performance liquid chromatography-tandem mass spectrometry].

    Science.gov (United States)

    Yang, Gang; Huang, Xianhui; Guo, Chunna; Fang, Qiuhua; He, Limin

    2012-06-01

    An analytical method was developed for the determination of clavulanic acid (CLAV) in milk by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). A 2 g milk sample was deproteinized by ethanol. The supernatant was transferred into a pear-shaped bottle to be evaporated to about 0.5 mL, and the residue was dissolved with ammonium acetate solution. The sample was determined by HPLC-MS/MS after the purification. The chromatographic separation was achieved on a Luna 5u C8 column using 0.1% formic acid in water and acetonitrile as mobile phases with gradient elution. The identification of CLAV was carried out by MS/MS equipped with electrospray ionization in negative scanning and multiple reaction monitoring (MRM) modes. Matrix-matched calibration standard was used for the quantification. The calibration curve showed perfect linear in the range of 10 - 400 microg/kg with the correlation coefficient of 0.999. The limit of detection (LOD, S/N > or = 3) was 10 microg/kg in milk, and the limit of quantification (LOQ, S/N > or = 10) was 20 microg/kg. The mean recoveries varied from 80.00% to 91.25% at the four spiked levels of LOQ, 1/2MRL (the maximum residue limit), MRL, and 2MRL with the relative standard deviations of 5.60% -8.77%. In conclusion, the established method can be applied for the determination of CLAV residues in milk.

  12. Contributions of a Position Amino Acid Residues to the Conformational Stability of GCN4 Leucine Zipper

    Institute of Scientific and Technical Information of China (English)

    WEI Xiang; ZENG Xian'gang; ZHOU Haimeng

    2006-01-01

    The stability of GCN4 leucine zipper and its four mutants in guanidine hydrochloride was detected to verify the contributions of different a position amino acid residues in polypeptide sequences to the forming and stability of parallel coiled coils. The changes of the circular dichroism spectra show that the displacement of the a position polar asparagine and the increase of asparagine in the GCN4 leucine zipper can reduce the α-helix content of the coiled coil structure. The mutants are less stable than the natural peptide in guanidine hydrochloride. The results show that the interaction between the polar asparagine contributes to the conformational stability of the coiled coil. Both the conformation and the number of polar residues in the coiled coil also affect the α-helix content and its resistance to the denaturant. The conclusions provide evidence describing the folding process of proteins including coiled coils in vivo.

  13. Synthesis and characterization of fac-Re(CO)3-aspartic-N-monoacetic acid, a structural analogue of a potential new renal tracer, fac-(99m)Tc(CO)3(ASMA).

    Science.gov (United States)

    Klenc, Jeffrey; Lipowska, Malgorzata; Taylor, Andrew T; Marzilli, Luigi G

    2012-09-01

    The reaction of an aminopolycarboxylate ligand, aspartic-N-monoacetic acid (ASMA), with [Re(CO)3(H2O)3](+) was examined. The tridentate coordination of ASMA to this Re(I) tricarbonyl precursor yielded fac-Re(CO)3(ASMA) as a mixture of diastereomers. The chemistry is analogous to that of the Tc(I) tricarbonyl complex, which yields fac-(99m)Tc(CO)3(ASMA) under similar conditions. The formation, structure, and isomerization of fac-Re(CO)3(ASMA) products were characterized by HPLC, (1)H NMR spectroscopy, and X-ray crystallography. The two major fac-Re(CO)3(ASMA) diastereomeric products each have a linear ONO coordination mode with two adjacent five-membered chelate rings, but they differ in the endo or exo orientation of the uncoordinated acetate group, in agreement with expectations based on previous studies. Conditions have been identified for the expedient isomerization of fac-Re(CO)3(ASMA) to a mixture consisting primarily of one major product. Because different isomeric species typically have different pharmacokinetic characteristics, these conditions may provide for the practical isolation of a single (99m)Tc(CO)3(ASMA) species, thus allowing the isolation of the isomer that has optimal imaging and pharmacokinetic characteristics. This information will aid in the design of future (99m)Tc radiopharmaceuticals.

  14. Topology of AspT, the aspartate:alanine antiporter of Tetragenococcus halophilus, determined by site-directed fluorescence labeling.

    Science.gov (United States)

    Nanatani, Kei; Fujiki, Takashi; Kanou, Kazuhiko; Takeda-Shitaka, Mayuko; Umeyama, Hideaki; Ye, Liwen; Wang, Xicheng; Nakajima, Tasuku; Uchida, Takafumi; Maloney, Peter C; Abe, Keietsu

    2007-10-01

    The gram-positive lactic acid bacterium Tetragenococcus halophilus catalyzes the decarboxylation of L-aspartate (Asp) with release of L-alanine (Ala) and CO(2). The decarboxylation reaction consists of two steps: electrogenic exchange of Asp for Ala catalyzed by an aspartate:alanine antiporter (AspT) and intracellular decarboxylation of the transported Asp catalyzed by an L-aspartate-beta-decarboxylase (AspD). AspT belongs to the newly classified aspartate:alanine exchanger family (transporter classification no. 2.A.81) of transporters. In this study, we were interested in the relationship between the structure and function of AspT and thus analyzed the topology by means of the substituted-cysteine accessibility method using the impermeant, fluorescent, thiol-specific probe Oregon Green 488 maleimide (OGM) and the impermeant, nonfluorescent, thiol-specific probe [2-(trimethylammonium)ethyl]methanethiosulfonate bromide. We generated 23 single-cysteine variants from a six-histidine-tagged cysteineless AspT template. A cysteine position was assigned an external location if the corresponding single-cysteine variant reacted with OGM added to intact cells, and a position was assigned an internal location if OGM labeling required cell lysis. The topology analyses revealed that AspT has a unique topology; the protein has 10 transmembrane helices (TMs), a large hydrophilic cytoplasmic loop (about 180 amino acids) between TM5 and TM6, N and C termini that face the periplasm, and a positively charged residue (arginine 76) within TM3. Moreover, the three-dimensional structure constructed by means of the full automatic modeling system indicates that the large hydrophilic cytoplasmic loop of AspT possesses a TrkA_C domain and a TrkA_C-like domain and that the three-dimensional structures of these domains are similar to each other even though their amino acid sequences show low similarity. PMID:17660287

  15. Topology of AspT, the aspartate:alanine antiporter of Tetragenococcus halophilus, determined by site-directed fluorescence labeling.

    Science.gov (United States)

    Nanatani, Kei; Fujiki, Takashi; Kanou, Kazuhiko; Takeda-Shitaka, Mayuko; Umeyama, Hideaki; Ye, Liwen; Wang, Xicheng; Nakajima, Tasuku; Uchida, Takafumi; Maloney, Peter C; Abe, Keietsu

    2007-10-01

    The gram-positive lactic acid bacterium Tetragenococcus halophilus catalyzes the decarboxylation of L-aspartate (Asp) with release of L-alanine (Ala) and CO(2). The decarboxylation reaction consists of two steps: electrogenic exchange of Asp for Ala catalyzed by an aspartate:alanine antiporter (AspT) and intracellular decarboxylation of the transported Asp catalyzed by an L-aspartate-beta-decarboxylase (AspD). AspT belongs to the newly classified aspartate:alanine exchanger family (transporter classification no. 2.A.81) of transporters. In this study, we were interested in the relationship between the structure and function of AspT and thus analyzed the topology by means of the substituted-cysteine accessibility method using the impermeant, fluorescent, thiol-specific probe Oregon Green 488 maleimide (OGM) and the impermeant, nonfluorescent, thiol-specific probe [2-(trimethylammonium)ethyl]methanethiosulfonate bromide. We generated 23 single-cysteine variants from a six-histidine-tagged cysteineless AspT template. A cysteine position was assigned an external location if the corresponding single-cysteine variant reacted with OGM added to intact cells, and a position was assigned an internal location if OGM labeling required cell lysis. The topology analyses revealed that AspT has a unique topology; the protein has 10 transmembrane helices (TMs), a large hydrophilic cytoplasmic loop (about 180 amino acids) between TM5 and TM6, N and C termini that face the periplasm, and a positively charged residue (arginine 76) within TM3. Moreover, the three-dimensional structure constructed by means of the full automatic modeling system indicates that the large hydrophilic cytoplasmic loop of AspT possesses a TrkA_C domain and a TrkA_C-like domain and that the three-dimensional structures of these domains are similar to each other even though their amino acid sequences show low similarity.

  16. Rubber recovery from centrifuged natural rubber latex residue using sulfuric acid

    Directory of Open Access Journals (Sweden)

    Wirach Taweepreda

    2013-04-01

    Full Text Available Waste latex sludge from centrifuged residue, which is a null by-product of concentrated latex manufacturing, wasdigested to retrieve the rubber by using sulfuric acid. It was found that the acid concentration and digestion time have aneffect on the amount and purity of the retrieved rubber. Sulfuric acid at concentrations of more than 10% by weight with adigestion time of 48 hours completely digested waste latex sludge and gave rubber 10% by weight. The quality of the retrievedrubber was examined for Mooney viscosity (MV, plasticity retention index, nitrogen content, and ash content. The averagemolecular weight of the retrieved rubber, using gel permeation chromatography, was lower than that of normal natural rubber(NR which corresponds with the MV and initial plasticity (Po. The molecular structure from Fourier transform infraredspectroscopy (FT-IR indicated that the retrieved rubber surface is wet composed with hydroxyl functional ended group.The residue solution was evaporated and crystallized. The structure of crystals was determined using power X-ray diffractometer.

  17. Crystal Structure of Cockroach Allergen Bla g 2, an Unusual Zinc Binding Aspartic Protease with a Novel Mode of Self-inhibition

    Energy Technology Data Exchange (ETDEWEB)

    Gustchina, Alla; Li, Mi; Wunschmann, Sabina; Chapman, Martin D.; Pomes, Anna; Wlodawer, Alexander (INDOOR Bio.); (NIH)

    2010-07-19

    The crystal structure of Bla g 2 was solved in order to investigate the structural basis for the allergenic properties of this unusual protein. This is the first structure of an aspartic protease in which conserved glycine residues, in two canonical DTG triads, are substituted by different amino acid residues. Another unprecedented feature revealed by the structure is the single phenylalanine residue insertion on the tip of the flap, with the side-chain occupying the S1 binding pocket. This and other important amino acid substitutions in the active site region of Bla g 2 modify the interactions in the vicinity of the catalytic aspartate residues, increasing the distance between them to {approx}4 {angstrom} and establishing unique direct contacts between the flap and the catalytic residues. We attribute the absence of substantial catalytic activity in Bla g 2 to these unusual features of the active site. Five disulfide bridges and a Zn-binding site confer stability to the protein, which may contribute to sensitization at lower levels of exposure than other allergens.

  18. DNA Three Way Junction Core Decorated with Amino Acids-Like Residues-Synthesis and Characterization.

    Science.gov (United States)

    Addamiano, Claudia; Gerland, Béatrice; Payrastre, Corinne; Escudier, Jean-Marc

    2016-01-01

    Construction and physico-chemical behavior of DNA three way junction (3WJ) functionalized by protein-like residues (imidazole, alcohol and carboxylic acid) at unpaired positions at the core is described. One 5'-C(S)-propargyl-thymidine nucleotide was specifically incorporated on each strand to react through a post synthetic CuACC reaction with either protected imidazolyl-, hydroxyl- or carboxyl-azide. Structural impacts of 5'-C(S)-functionalization were investigated to evaluate how 3WJ flexibility/stability is affected. PMID:27563857

  19. DNA Three Way Junction Core Decorated with Amino Acids-Like Residues-Synthesis and Characterization

    Directory of Open Access Journals (Sweden)

    Claudia Addamiano

    2016-08-01

    Full Text Available Construction and physico-chemical behavior of DNA three way junction (3WJ functionalized by protein-like residues (imidazole, alcohol and carboxylic acid at unpaired positions at the core is described. One 5′-C(S-propargyl-thymidine nucleotide was specifically incorporated on each strand to react through a post synthetic CuACC reaction with either protected imidazolyl-, hydroxyl- or carboxyl-azide. Structural impacts of 5′-C(S-functionalization were investigated to evaluate how 3WJ flexibility/stability is affected.

  20. A Nitrogen-concentrated Phase in IA Iron Meteorite Acid Residue

    Science.gov (United States)

    Hashizume, K.; Sugiura, N.

    1993-07-01

    Introduction: Iron meteorites are considered to have experienced a complex history, which is indicated by the variations in trace element chemistry (e.g., [1]). Among iron meteorite groups, the so called nonmagmatic groups, such as IAB, IIE, and IIICD, may have passed through different formation paths compared to others. Nitrogen isotopes can be a useful tool to understand the origin and formation processes of iron meteorites. Nikogen isotopes in a number of iron meteorites are measured [2,3], although trapping sites of nitrogen in iron meteorites are not yet clear. This is an important issue because nitrogen, a typical mobile element, may well reflect thermal history of their parent bodies (c.f., [4]). Generally, a major portion of nitrogen in iron meteorites is expected to be in a solid solution in Fe-Ni, especially in f.c.c. Fe-Ni (taenite). Franchi et al. [3] report that at least 25 to 35% of nitrogen in magmatic iron meteorites is in acid insoluble phases, however, not in those of non-magmatic meteorites. This result contradicts with the result [5] who report that a significant portion of nitrogen seems to be trapped in acid residues not only of magmatic meteorites but also of non- magmatic meteorites. To resolve the contradiction described above, and to identify the trapping site, we started measuring nitrogen isotopes in acid residues of iron metcorites. We report here preliminary results on acid residues of Canyon Diablo (IA). Procedures: Acid residues were prepared by Dr. J.-I. Matsuda and his colleagues. Different blocks of Canyon Diablo, "Can-1" and "Can-2" were treated by 14M HCl, 10M-HF + 1M-HCl, 1M-HCl, and by aqua regia, which destroyed Fe-Ni, sulfides, silicates, and shreibersite. Acid residues of these two blocks, "Can-1bn" and "Can-2b," yielded 0.102 wt% and 0.299 wt% of their original masses, respectively These residues seem to consist mostly of graphite No diamond was detected by powder X-ray analysis [6]. Preliminary Results: A predominant

  1. Optimization of thermal-dilute sulfuric acid pretreatment for enhancement of methane production from cassava residues.

    Science.gov (United States)

    Zhang, Qinghua; Tang, Lei; Zhang, Jianhua; Mao, Zhonggui; Jiang, Li

    2011-02-01

    In this study, the pretreatment of cassava residues by thermal-dilute sulfuric acid (TDSA) hydrolysis was investigated by means of a statistically designed set of experiments. A three-factor central composite design (CCD) was employed to identify the optimum pretreatment condition of cassava residues for methane production. The individual and interactive effects of temperature, H(2)SO(4) concentration and reaction time on increase of methane yield (IMY) were evaluated by applying response surface methodology (RSM). After optimization, the resulting optimum pretreatment condition was 157.84°C, utilizing 2.99% (w/w TS) H(2)SO(4) for 20.15 min, where the maximum methane yield (248 mL/g VS) was 56.96% higher than the control (158 mL/g VS), which was very close to the predict value 56.53%. These results indicate the model obtained through RSM analysis is suit to predict the optimum pretreatment condition and there is great potential of using TDSA pretreatment of cassava residues to enhance methane yield.

  2. The myeloperoxidase-derived oxidant hypothiocyanous acid inhibits protein tyrosine phosphatases via oxidation of key cysteine residues

    DEFF Research Database (Denmark)

    Cook, Naomi L.; Moeke, Cassidy H.; Fantoni, Luca I.;

    2016-01-01

    , can modulate the activity of multiple members of the PTP superfamily via oxidation of Cys residues to sulfenic acids. This alteration of the balance of PTP/kinase activity may perturb protein phosphorylation and disrupt cell signaling with subsequent induction of apoptosis at sites of inflammation.......-) oxidation by H2O2 to form hypothiocyanous acid (HOSCN), an oxidant that targets Cys residues. Dysregulated phosphorylation and elevated MPO levels have been associated with chronic inflammatory diseases where HOSCN can be generated. Previous studies have shown that HOSCN inhibits isolated PTP1B and induces......-PTP; CD45 and Src homology phosphatase-1, Shp-1) by targeting Cys residues. Isolated PTP activity, and activity in lysates of human monocyte-derived macrophages (HMDM) was inhibited by 0-100 μM HOSCN with this being accompanied by reversible oxidation of Cys residues, formation of sulfenic acids...

  3. Identification of key amino acid residues modulating intracellular and in vitro microcin E492 amyloid formation

    Directory of Open Access Journals (Sweden)

    Paulina eAguilera

    2016-01-01

    Full Text Available Microcin E492 (MccE492 is a pore-forming bacteriocin produced and exported by Klebsiella pneumoniae RYC492. Besides its antibacterial activity, excreted MccE492 can form amyloid fibrils in vivo as well as in vitro. It has been proposed that bacterial amyloids can be functional playing a biological role, and in the particular case of MccE492 it would control the antibacterial activity. MccE492 amyloid fibril’s morphology and formation kinetics in vitro have been well characterized, however it is not known which amino acid residues determine its amyloidogenic propensity, nor if it forms intracellular amyloid inclusions as has been reported for other bacterial amyloids. In this work we found the conditions in which MccE492 forms intracellular amyloids in E. coli cells, that were visualized as round-shaped inclusion bodies recognized by two amyloidophillic probes, 2-4´-methylaminophenyl benzothiazole and thioflavin-S. We used this property to perform a flow cytometry-based assay to evaluate the aggregation propensity of MccE492 mutants, that were designed using an in silico prediction of putative aggregation hotspots. We established that the predicted amino acid residues 54-63, effectively act as a pro-amyloidogenic stretch. As in the case of other amyloidogenic proteins, this region presented two gatekeeper residues (P57 and P59, which disfavor both intracellular and in vitro MccE492 amyloid formation, preventing an uncontrolled aggregation. Mutants in each of these gatekeeper residues showed faster in vitro aggregation and bactericidal inactivation kinetics, and the two mutants were accumulated as dense amyloid inclusions in more than 80% of E. coli cells expressing these variants. In contrast, the MccE492 mutant lacking residues 54-63 showed a significantly lower intracellular aggregation propensity and slower in vitro polymerization kinetics. Electron microscopy analysis of the amyloids formed in vitro by these mutants revealed that, although

  4. SeqX: a tool to detect, analyze and visualize residue co-locations in protein and nucleic acid structures

    Directory of Open Access Journals (Sweden)

    Fördös Gergely

    2005-07-01

    Full Text Available Abstract Background The interacting residues of protein and nucleic acid sequences are close to each other – they are co-located. Structure databases (like Protein Data Bank, PDB and Nucleic Acid Data Bank, NDB contain all information about these co-locations; however it is not an easy task to penetrate this complex information. We developed a JAVA tool, called SeqX for this purpose. Results SeqX tool is useful to detect, analyze and visualize residue co-locations in protein and nucleic acid structures. The user a. selects a structure from PDB; b. chooses an atom that is commonly present in every residues of the nucleic acid and/or protein structure(s c. defines a distance from these atoms (3–15 Å. The SeqX tool detects every residue that is located within the defined distances from the defined "backbone" atom(s; provides a DotPlot-like visualization (Residues Contact Map, and calculates the frequency of every possible residue pairs (Residue Contact Table in the observed structure. It is possible to exclude +/- 1 to 10 neighbor residues in the same polymeric chain from detection, which greatly improves the specificity of detections (up to 60% when tested on dsDNA. Results obtained on protein structures showed highly significant correlations with results obtained from literature (p Conclusion The tool is simple and easy to use and provides a quick and reliable visualization and analyses of residue co-locations in protein and nucleic acid structures. Availability and requirements http://janbiro.com/Downloads.html SeqX, Java J2SE Runtime Environment 5.0 (available from [see Additional file 1] http://www.sun.com and at least a 1 GHz processor and with a minimum 256 Mb RAM. Source codes are available from the authors. Additional File 1 SeqX_1.041_05601.jar. see this article Click here for file

  5. Accurate prediction of hot spot residues through physicochemical characteristics of amino acid sequences

    KAUST Repository

    Chen, Peng

    2013-07-23

    Hot spot residues of proteins are fundamental interface residues that help proteins perform their functions. Detecting hot spots by experimental methods is costly and time-consuming. Sequential and structural information has been widely used in the computational prediction of hot spots. However, structural information is not always available. In this article, we investigated the problem of identifying hot spots using only physicochemical characteristics extracted from amino acid sequences. We first extracted 132 relatively independent physicochemical features from a set of the 544 properties in AAindex1, an amino acid index database. Each feature was utilized to train a classification model with a novel encoding schema for hot spot prediction by the IBk algorithm, an extension of the K-nearest neighbor algorithm. The combinations of the individual classifiers were explored and the classifiers that appeared frequently in the top performing combinations were selected. The hot spot predictor was built based on an ensemble of these classifiers and to work in a voting manner. Experimental results demonstrated that our method effectively exploited the feature space and allowed flexible weights of features for different queries. On the commonly used hot spot benchmark sets, our method significantly outperformed other machine learning algorithms and state-of-the-art hot spot predictors. The program is available at http://sfb.kaust.edu.sa/pages/software.aspx. © 2013 Wiley Periodicals, Inc.

  6. Quantitative solid state NMR analysis of residues from acid hydrolysis of loblolly pine wood.

    Science.gov (United States)

    Sievers, Carsten; Marzialetti, Teresita; Hoskins, Travis J C; Valenzuela Olarte, Mariefel B; Agrawal, Pradeep K; Jones, Christopher W

    2009-10-01

    The composition of solid residues from hydrolysis reactions of loblolly pine wood with dilute mineral acids is analyzed by (13)C Cross Polarization Magic Angle Spinning (CP MAS) NMR spectroscopy. Using this method, the carbohydrate and lignin fractions are quantified in less than 3h as compared to over a day using wet chemical methods. In addition to the quantitative information, (13)C CP MAS NMR spectroscopy provides information on the formation of additional extractives and pseudo lignin from the carbohydrates. Being a non-destructive technique, NMR spectroscopy provides unambiguous evidence of the presence of side reactions and products, which is a clear advantage over the wet chemical analytical methods. Quantitative results from NMR spectroscopy and proximate analysis are compared for the residues from hydrolysis of loblolly pine wood under 13 different conditions; samples were treated either at 150 degrees C or 200 degrees C in the presence of various acids (HCl, H(2)SO(4), H(3)PO(4), HNO(3) and TFA) or water. The lignin content determined by both methods differed on averaged by 2.9 wt% resulting in a standard deviation of 3.5 wt%. It is shown that solid degradation products are formed from saccharide precursors under harsh reaction conditions. These degradation reactions limit the total possible yield of monosaccharides from any subsequent reaction. PMID:19477123

  7. Glycolic acid-catalyzed deamidation of asparagine residues in degrading PLGA matrices: a computational study.

    Science.gov (United States)

    Manabe, Noriyoshi; Kirikoshi, Ryota; Takahashi, Ohgi

    2015-03-31

    Poly(lactic-co-glycolic acid) (PLGA) is a strong candidate for being a drug carrier in drug delivery systems because of its biocompatibility and biodegradability. However, in degrading PLGA matrices, the encapsulated peptide and protein drugs can undergo various degradation reactions, including deamidation at asparagine (Asn) residues to give a succinimide species, which may affect their potency and/or safety. Here, we show computationally that glycolic acid (GA) in its undissociated form, which can exist in high concentration in degrading PLGA matrices, can catalyze the succinimide formation from Asn residues by acting as a proton-transfer mediator. A two-step mechanism was studied by quantum-chemical calculations using Ace-Asn-Nme (Ace = acetyl, Nme = NHCH3) as a model compound. The first step is cyclization (intramolecular addition) to form a tetrahedral intermediate, and the second step is elimination of ammonia from the intermediate. Both steps involve an extensive bond reorganization mediated by a GA molecule, and the first step was predicted to be rate-determining. The present findings are expected to be useful in the design of more effective and safe PLGA devices.

  8. Substrate Specificity of the Aspartate:Alanine Antiporter (AspT) of Tetragenococcus halophilus in Reconstituted Liposomes*

    OpenAIRE

    Sasahara, Ayako; Nanatani, Kei; Enomoto, Masaru; Kuwahara, Shigefumi; Abe, Keietsu

    2011-01-01

    The aspartate:alanine antiporter (AspT) of the lactic acid bacterium Tetragenococcus halophilus is a member of the aspartate:alanine exchanger (AAEx) transporter family. T. halophilus AspT catalyzes the electrogenic exchange of l-aspartate1− with l-alanine0. Although physiological functions of AspT were well studied, l-aspartate1−:l-alanine0 antiport mechanisms are still unsolved. Here we report that the binding sites of l-aspartate and l-alanine are independently present in AspT by means of ...

  9. SeqX: a tool to detect, analyze and visualize residue co-locations in protein and nucleic acid structures

    OpenAIRE

    Fördös Gergely; Biro Jan C

    2005-01-01

    Abstract Background The interacting residues of protein and nucleic acid sequences are close to each other – they are co-located. Structure databases (like Protein Data Bank, PDB and Nucleic Acid Data Bank, NDB) contain all information about these co-locations; however it is not an easy task to penetrate this complex information. We developed a JAVA tool, called SeqX for this purpose. Results SeqX tool is useful to detect, analyze and visualize residue co-locations in protein and nucleic acid...

  10. Covalent aspartylation of aspartyl-tRNA synthetase from Bakers' yeast by its cognat aspartyl adenylate: identification of the labeled residues

    Energy Technology Data Exchange (ETDEWEB)

    Mejdoub, H.; Kern, D.; Giege, R.; Ebel, J.P.; Boulanger, Y.; Reinbolt, J.

    1987-04-07

    Aspartyl-tRNA synthetase from bakers' yeast gives an unstable complex with the cognate adenylate, which reacts after dissociation with amino acid side chains of the protein. This leads to a covalent incorporation of (/sup 14/C)-aspartic acid into aspartyl-tRNA synthetase via amide or ester bonds formed between the ..cap alpha..-carboxyl group of activated aspartic acid and accessible lysines, serines, and threonines. This property is used to label the peptides at the surface of the enzyme. The main labeled residues have been identified, and their location in the primary structure is discussed in relation to structural properties of aspartyl-tRNA synthetase.

  11. Amino acid substitutions of conserved residues in the carboxyl-terminal domain of the [alpha]I(X) chain of type X collagen occur in two unrelated families with metaphyseal chondrodysplasia type Schmid

    Energy Technology Data Exchange (ETDEWEB)

    Wallis, G.A.; Rash, B.; Sweetman, W.A.; Thomas, J.T.; Grant, M.E.; Boot-Handford, R.P. (Univ. of Manchester (United Kingdom)); Super, M. (Royal Manchester Children' s Hospital, Manchester (United Kingdom)); Evans, G. (Robert Jones Orthopaedic Hospital, Oswestry (United Kingdom))

    1994-02-01

    Type X collagen is a homotrimeric, short-chain, nonfibrillar extracellular-matrix component that is specifically and transiently synthesized by hypertrophic chondrocytes at the site of endochondral ossification. The precise function of type X collagen is not known, but its specific pattern of expression suggests that mutations within the encoding gene (COL10A1) that alter the structure or synthesis of the protein may cause heritable forms of chondrodysplasia. The authors used the PCR and the SSCP techniques to analyze the coding and upstream promoter regions of the COL10A1 gene in a number of individuals with forms of chondrodysplasia. Using this approach, they identified two individuals with metaphyseal chondrodysplasia type Schmid (MCDS) with SSCP changes in the region of the gene encoding the carboxyl-terminal domain. Sequence analysis demonstrated that the individuals were heterozygous for two unique single-base-pair transitions that led to the substitution of the highly conserved amino acid residue tyrosine at position 598 by aspartic acid in one person and of leucine at position 614 by proline in the other. The substitution at residue 598 segregated with the phenotype in a family of eight (five affected and three unaffected) related persons. The substitutions at residue 614 occurred in a sporadically affected individual but not in her unaffected mother and brother. Additional members of this family were not available for further study. These results suggest that certain amino acid substitutions within the carboxyl-terminal domain of the chains of the type X collagen molecule cause MCDS. These amino acid substitutions are likely to alter either chain recognition or assembly of the type X collagen molecule, thereby depleting the amount of normal type X collagen deposited in the extracellular matrix, with consequent aberrations in bone growth and development. 36 refs., 5 figs.

  12. New force field parameters for metalloproteins I: Divalent copper ion centers including three histidine residues and an oxygen-ligated amino acid residue.

    Science.gov (United States)

    Wise, Olivia; Coskuner, Orkid

    2014-06-30

    Transition metal ion complexation with proteins is ubiquitous across such diverse fields as neurodegenerative and cardiovascular diseases and cancer. In this study, the structures of divalent copper ion centers including three histidine and one oxygen-ligated amino acid residues and the relative binding affinities of the oxygen-ligated amino acid residues with these metal ion centers, which are debated in the literature, are presented. Furthermore, new force field parameters, which are currently lacking for the full-length metal-ligand moieties, are developed for metalloproteins that have these centers. These new force field parameters enable investigations of metalloproteins possessing these binding sites using molecular simulations. In addition, the impact of using the atom equivalence and inequivalence atomic partial charge calculation procedures on the simulated structures of these metallopeptides, including hydration properties, is described.

  13. Substrate specificity of the aspartate:alanine antiporter (AspT) of Tetragenococcus halophilus in reconstituted liposomes.

    Science.gov (United States)

    Sasahara, Ayako; Nanatani, Kei; Enomoto, Masaru; Kuwahara, Shigefumi; Abe, Keietsu

    2011-08-19

    The aspartate:alanine antiporter (AspT) of the lactic acid bacterium Tetragenococcus halophilus is a member of the aspartate:alanine exchanger (AAEx) transporter family. T. halophilus AspT catalyzes the electrogenic exchange of L-aspartate(1-) with L-alanine(0). Although physiological functions of AspT were well studied, L-aspartate(1-):L-alanine(0) antiport mechanisms are still unsolved. Here we report that the binding sites of L-aspartate and L-alanine are independently present in AspT by means of the kinetic studies. We purified His(6)-tagged T. halophilus AspT and characterized its kinetic properties when reconstituted in liposomes (K(m) = 0.35 ± 0.03 mm for L-aspartate, K(m) = 0.098 ± 0 mm for D-aspartate, K(m) = 26 ± 2 mm for L-alanine, K(m) = 3.3 ± 0.2 mm for D-alanine). Competitive inhibition by various amino acids of L-aspartate or L-alanine in self-exchange reactions revealed that L-cysteine selectively inhibited L-aspartate self-exchange but only weakly inhibited L-alanine self-exchange. Additionally, L-serine selectively inhibited L-alanine self-exchange but barely inhibited L-aspartate self-exchange. The aspartate analogs L-cysteine sulfinic acid, L-cysteic acid, and D-cysteic acid competitively and strongly inhibited L-aspartate self-exchange compared with L-alanine self-exchange. Taken together, these kinetic data suggest that the putative binding sites of L-aspartate and L-alanine are independently located in the substrate translocation pathway of AspT. PMID:21719707

  14. Substrate Specificity of the Aspartate:Alanine Antiporter (AspT) of Tetragenococcus halophilus in Reconstituted Liposomes*

    Science.gov (United States)

    Sasahara, Ayako; Nanatani, Kei; Enomoto, Masaru; Kuwahara, Shigefumi; Abe, Keietsu

    2011-01-01

    The aspartate:alanine antiporter (AspT) of the lactic acid bacterium Tetragenococcus halophilus is a member of the aspartate:alanine exchanger (AAEx) transporter family. T. halophilus AspT catalyzes the electrogenic exchange of l-aspartate1− with l-alanine0. Although physiological functions of AspT were well studied, l-aspartate1−:l-alanine0 antiport mechanisms are still unsolved. Here we report that the binding sites of l-aspartate and l-alanine are independently present in AspT by means of the kinetic studies. We purified His6-tagged T. halophilus AspT and characterized its kinetic properties when reconstituted in liposomes (Km = 0.35 ± 0.03 mm for l-aspartate, Km = 0.098 ± 0 mm for d-aspartate, Km = 26 ± 2 mm for l-alanine, Km = 3.3 ± 0.2 mm for d-alanine). Competitive inhibition by various amino acids of l-aspartate or l-alanine in self-exchange reactions revealed that l-cysteine selectively inhibited l-aspartate self-exchange but only weakly inhibited l-alanine self-exchange. Additionally, l-serine selectively inhibited l-alanine self-exchange but barely inhibited l-aspartate self-exchange. The aspartate analogs l-cysteine sulfinic acid, l-cysteic acid, and d-cysteic acid competitively and strongly inhibited l-aspartate self-exchange compared with l-alanine self-exchange. Taken together, these kinetic data suggest that the putative binding sites of l-aspartate and l-alanine are independently located in the substrate translocation pathway of AspT. PMID:21719707

  15. Structural Analysis of the Ligand-Binding Domain of the Aspartate Receptor Tar from Escherichia coli.

    Science.gov (United States)

    Mise, Takeshi

    2016-07-01

    The Escherichia coli cell-surface aspartate receptor Tar mediates bacterial chemotaxis toward an attractant, aspartate (Asp), and away from a repellent, Ni(2+). These signals are transmitted from the extracellular region of Tar to the cytoplasmic region via the transmembrane domain. The mechanism by which extracellular signals are transmitted into the cell through conformational changes in Tar is predicted to involve a piston displacement of one of the α4 helices of the homodimer. To understand the molecular mechanisms underlying the induction of Tar activity by an attractant, the three-dimensional structures of the E. coli Tar periplasmic domain with and without bound aspartate, Asp-Tar and apo-Tar, respectively, were determined. Of the two ligand-binding sites, only one site was occupied, and it clearly showed the electron density of an aspartate. The slight changes in conformation and the electrostatic surface potential around the aspartate-binding site were observed. In addition, the presence of an aspartate stabilized residues Phe-150' and Arg-73. A pistonlike displacement of helix α4b' was also induced by aspartate binding as predicted by the piston model. Taken together, these small changes might be related to the induction of Tar activity and might disturb binding of the second aspartate to the second binding site in E. coli. PMID:27292793

  16. Improved postprandial glycaemic control with insulin Aspart in type 2 diabetic patients treated with insulin

    DEFF Research Database (Denmark)

    Rosenfalck, A M; Thorsby, P; Kjems, L;

    2000-01-01

    The effect on postprandial blood glucose control of an immediately pre-meal injection of the rapid acting insulin analogue Aspart (IAsp) was compared with that of human insulin Actrapid injected immediately or 30 minutes before a test meal in insulin-treated type 2 diabetic patients with residual...... that the improved glucose control previously demonstrated with insulin Aspart compared to human insulin in healthy subjects and type 1 diabetic patients also applies to insulin-treated type 2 diabetic patients....

  17. Membrane topology of aspartate:alanine antiporter AspT from Comamonas testosteroni.

    Science.gov (United States)

    Fujiki, Takashi; Nanatani, Kei; Nishitani, Kei; Yagi, Kyoko; Ohnishi, Fumito; Yoneyama, Hiroshi; Uchida, Takafumi; Nakajima, Tasuku; Abea, Keietsu

    2007-01-01

    We cloned the aspT gene encoding the L-aspartate:L-alanine antiporter AspTCt in Comamonas testosteroni genomic DNA. Analysis of the nucleotide sequence revealed that C. testosteroni has an asp operon containing aspT upstream of the l-aspartate 4-decarboxylase gene, and that the gene order of the asp operon of C. testosteroni is the inverse of that of Tetragenococcus halophilus. We used proteoliposomes to confirm the transport processes of AspTCt. To elucidate the two-dimensional structure of AspTCt, we analysed its membrane topology by means of alkaline phosphatase (PhoA) and beta-lactamase (BlaM) fusion methods. The fusion analyses revealed that AspTCt has seven transmembrane segments (TMs), a large cytoplasmic loop containing approximately 200 amino acid residues between TM4 and TM5, a cytoplasmic N-terminus, and a periplasmic C-terminus. These results suggest that the orientation of the N-terminus of AspTCt differs from that of tetragenococcal AspT, even though these two AspT orthologues catalyse the same transport reactions. PMID:17158863

  18. Utility of intraoperative fluorescent diagnosis of residual hemangioblastoma using 5-aminolevulinic acid

    Directory of Open Access Journals (Sweden)

    Satoshi Utsuki

    2011-01-01

    Full Text Available Hemangioblastoma is a benign tumor of the cerebellum, and treatment involves surgical excision, both as the initial treatment and also in case of recurrence. Recurrence of hemangioblastoma can be local due to incomplete resection or can be distant and separate from the tumor resection region. Local recurrence can largely be avoided by verifying for any residual tumor intraoperatively before closure. In this study, we used intraoperative fluorescent diagnosis using 5-aminolevulinic acid (5-ALA to verify the presence of a residual tumor during surgical resection. Nine patients with hemangioblastoma were given 1 g of 5-ALA orally before surgery, and a laser beam of 405 nm was focused on the tumor during resective surgery. Fluorescence of protoporphyrin IX (PPIX was observed in the core of tumor in all the cases. Fluorescence of PPIX was observed in the peritumoral cyst wall in two patients after tumor resection, and in both of them fluorescent parts of PPIX were resected and histological examination showed tumor cells. Usually, there are no tumor cells in the peritumoral cyst of a hemangioblastoma, yet hemangioblastomas may sometimes recur from an unresected cyst wall. It is thus necessary to excise an infiltrating cyst of tumor cells to prevent recurrence. Intraoperative fluorescent diagnosis using 5-ALA is a useful method to discern whether tumor cells are present in the peritumoral cyst wall of a hemangioblastoma.

  19. Chemical modification of an alpha 3-fucosyltransferase; definition of amino acid residues essential for enzyme activity.

    Science.gov (United States)

    Britten, C J; Bird, M I

    1997-02-11

    The biosynthesis of the carbohydrate antigen sialyl Lewis X (sLe(x)) is dependent on the activity of an alpha 3-fucosyltransferase (EC 2.4.1.152, GDP-fucose:Gal beta (1-4)GlcNAc-R alpha (1-3)fucosyltransferase). This enzyme catalyses the transfer of fucose from GDP-beta-fucose to the 3-OH of N-acetylglucosamine present in lactosamine acceptors. In this report, we have investigated the amino acids essential for the activity of a recombinant alpha 3-fucosyltransferase (FucT-VI) through chemical modification of the enzyme with group-selective reagents. FucT-VI activity was found to be particularly sensitive to the histidine-selective reagent diethylpyrocarbonate and the cysteine reagent N-ethylmaleimide, with IC50 values of less than 200 microM. Reagents selective for arginine and lysine had no effect on enzyme activity. The inclusion of GDP-beta-fucose during preincubation with NEM reduces the rate of inactivation whereas inclusion of an acceptor saccharide for the enzyme, Gal beta (1-4)GlcNAc, had no effect. No protective effect with either GDP-beta-fucose or Gal beta (1-4)GlcNAc was observed on treatment of the enzyme with diethylpyrocarbonate. These data suggest that in addition to an NEM-reactive cysteine in, or adjacent to, the substrate-binding site of the enzyme, FucT-VI possesses histidine residue(s) that are essential for enzyme activity.

  20. Residue Geometry Networks: A Rigidity-Based Approach to the Amino Acid Network and Evolutionary Rate Analysis.

    Science.gov (United States)

    Fokas, Alexander S; Cole, Daniel J; Ahnert, Sebastian E; Chin, Alex W

    2016-01-01

    Amino acid networks (AANs) abstract the protein structure by recording the amino acid contacts and can provide insight into protein function. Herein, we describe a novel AAN construction technique that employs the rigidity analysis tool, FIRST, to build the AAN, which we refer to as the residue geometry network (RGN). We show that this new construction can be combined with network theory methods to include the effects of allowed conformal motions and local chemical environments. Importantly, this is done without costly molecular dynamics simulations required by other AAN-related methods, which allows us to analyse large proteins and/or data sets. We have calculated the centrality of the residues belonging to 795 proteins. The results display a strong, negative correlation between residue centrality and the evolutionary rate. Furthermore, among residues with high closeness, those with low degree were particularly strongly conserved. Random walk simulations using the RGN were also successful in identifying allosteric residues in proteins involved in GPCR signalling. The dynamic function of these residues largely remain hidden in the traditional distance-cutoff construction technique. Despite being constructed from only the crystal structure, the results in this paper suggests that the RGN can identify residues that fulfil a dynamical function. PMID:27623708

  1. Topology of AspT, the Aspartate:Alanine Antiporter of Tetragenococcus halophilus, Determined by Site-Directed Fluorescence Labeling▿ †

    OpenAIRE

    Nanatani, Kei; Fujiki, Takashi; Kanou, Kazuhiko; Takeda-Shitaka, Mayuko; Umeyama, Hideaki; Ye, Liwen; WANG, XICHENG; Nakajima, Tasuku; Uchida, Takafumi; Maloney, Peter C.; Abe, Keietsu

    2007-01-01

    The gram-positive lactic acid bacterium Tetragenococcus halophilus catalyzes the decarboxylation of l-aspartate (Asp) with release of l-alanine (Ala) and CO2. The decarboxylation reaction consists of two steps: electrogenic exchange of Asp for Ala catalyzed by an aspartate:alanine antiporter (AspT) and intracellular decarboxylation of the transported Asp catalyzed by an l-aspartate-β-decarboxylase (AspD). AspT belongs to the newly classified aspartate:alanine exchanger family (transporter cla...

  2. Identification of glutamic acid 646 as a zinc-coordinating residue in endopeptidase-24.11.

    Science.gov (United States)

    Le Moual, H; Devault, A; Roques, B P; Crine, P; Boileau, G

    1991-08-25

    Neutral endopeptidase (EC 3.424.11, NEP) is a membrane-bound zinc-metallopeptidase. The substrate specificity and catalytic activity of NEP resemble those of thermolysin, a bacterial zinc-metalloprotease. Comparison of the primary structure of both enzymes suggests that several amino acids present in the active site of thermolysin are also found in NEP. Using site-directed mutagenesis of the cDNA encoding the NEP sequence, we have already shown that His residues 583 and 587 are two of the three zinc ligands. In order to identify the third zinc ligand, we have substituted Val or Asp for Glu616 or Glu646. Val616 NEP showed the same kinetic parameters as the non-mutated NEP. In contrast, the mutant Val646 NEP was almost completely devoid of catalytic activity and unable to bind the tritiated inhibitor [3H]N-[2(R,S)-3-hydroxyaminocarbonyl-2-benzyl-1-oxypropyl]gl ycine, the binding of which is dependent on the presence of the zinc ion. Replacing Glu for Asp at position 646 conserved the negative charge, and the mutant enzyme exhibited the same Km value as the non-mutated enzyme, but kCat was decreased to less than 3% of the value of the non-mutated enzyme. When compared to the non-mutated enzyme Asp646 NEP showed a higher susceptibility to chelating agents, but bound the tritiated inhibitor with the same affinity. Taken together, these observations strongly suggest that Glu646 of NEP is the third zinc-coordinating residue and is equivalent to Glu166 in thermolysin.

  3. Aspartic protease inhibitory and nematocidal activity of phenyl-4-(2-phenylhydrazonohexahydrofuro[3,2-c]pyridazin-7-ol (Percival dianhydroosazone

    Directory of Open Access Journals (Sweden)

    El Sayed H. El Ashry

    2014-04-01

    Full Text Available We synthesized Phenyl-4-(2-phenylhydrazonohexahydrofuro[3,2-c]pyridazin-7-ol (compound 3. The structure compound 3 was elucidated with IR, 1H NMR, 13C NMR and EIMS spectra. Compound 3 showed potent inhibitory activity against aspartic proteases, human cathepsin D and Plasmodium falciparum plasmepsin-II with IC50 = 20 μM. Enzyme-inhibitor complexes were predicted to stabilize by electrostatic and hydrophobic interactions between the side chains of amino acid residues at the active center and compound 3. Moreover, compound 3 displayed good nematocidal activity against all developmental stages of C. elegans.

  4. Sequence and structural features of binding site residues in protein-protein complexes: comparison with protein-nucleic acid complexes

    Directory of Open Access Journals (Sweden)

    Selvaraj S

    2011-10-01

    Full Text Available Abstract Background Protein-protein interactions are important for several cellular processes. Understanding the mechanism of protein-protein recognition and predicting the binding sites in protein-protein complexes are long standing goals in molecular and computational biology. Methods We have developed an energy based approach for identifying the binding site residues in protein–protein complexes. The binding site residues have been analyzed with sequence and structure based parameters such as binding propensity, neighboring residues in the vicinity of binding sites, conservation score and conformational switching. Results We observed that the binding propensities of amino acid residues are specific for protein-protein complexes. Further, typical dipeptides and tripeptides showed high preference for binding, which is unique to protein-protein complexes. Most of the binding site residues are highly conserved among homologous sequences. Our analysis showed that 7% of residues changed their conformations upon protein-protein complex formation and it is 9.2% and 6.6% in the binding and non-binding sites, respectively. Specifically, the residues Glu, Lys, Leu and Ser changed their conformation from coil to helix/strand and from helix to coil/strand. Leu, Ser, Thr and Val prefer to change their conformation from strand to coil/helix. Conclusions The results obtained in this study will be helpful for understanding and predicting the binding sites in protein-protein complexes.

  5. Enzyme active site mimics based on TriAzaCyclophane (TAC)-scaffolded peptides and amino acid residues

    NARCIS (Netherlands)

    Albada, H.B.

    2009-01-01

    This thesis describes the scope and limitations of the application of TriAzaCyclophane (TAC)-scaffolded peptides or amino acid residues as enzyme active site mimics, as ligands in asymmetric catalysis and as hydrolysis catalysts attached to vancomycin. For the mimicry of functional group enzymes, of

  6. Queen survival and oxalic acid residues in sugar stores after summer application against Varroa destructor in honey bees (Apis mellifera)

    NARCIS (Netherlands)

    Cornelissen, B.; Donders, J.N.L.C.; Stratum, van P.; Blacquière, T.; Dooremalen, van C.

    2012-01-01

    Methods using oxalic acid (OA) to control Varroa destructor in honey bee (Apis mellifera) colonies are widely applied. In this study, the effects of an OA spray application in early summer on the survival of young and old queens, and on OA residues in sugar stores were investigated. A questionnaire

  7. Conserved charged amino acid residues in the extracellular region of sodium/iodide symporter are critical for iodide transport activity

    Directory of Open Access Journals (Sweden)

    Liang Ji-An

    2010-11-01

    Full Text Available Abstract Background Sodium/iodide symporter (NIS mediates the active transport and accumulation of iodide from the blood into the thyroid gland. His-226 located in the extracellular region of NIS has been demonstrated to be critical for iodide transport in our previous study. The conserved charged amino acid residues in the extracellular region of NIS were therefore characterized in this study. Methods Fourteen charged residues (Arg-9, Glu-79, Arg-82, Lys-86, Asp-163, His-226, Arg-228, Asp-233, Asp-237, Arg-239, Arg-241, Asp-311, Asp-322, and Asp-331 were replaced by alanine. Iodide uptake abilities of mutants were evaluated by steady-state and kinetic analysis. The three-dimensional comparative protein structure of NIS was further modeled using sodium/glucose transporter as the reference protein. Results All the NIS mutants were expressed normally in the cells and targeted correctly to the plasma membrane. However, these mutants, except R9A, displayed severe defects on the iodide uptake. Further kinetic analysis revealed that mutations at conserved positively charged amino acid residues in the extracellular region of NIS led to decrease NIS-mediated iodide uptake activity by reducing the maximal rate of iodide transport, while mutations at conserved negatively charged residues led to decrease iodide transport by increasing dissociation between NIS mutants and iodide. Conclusions This is the first report characterizing thoroughly the functional significance of conserved charged amino acid residues in the extracellular region of NIS. Our data suggested that conserved charged amino acid residues, except Arg-9, in the extracellular region of NIS were critical for iodide transport.

  8. The Botrytis cinerea aspartic proteinase family

    NARCIS (Netherlands)

    Have, ten A.; Espino, J.J.; Dekkers, E.; Sluyter, Van S.; Brito, N.; Kay, J.; González, C.; Kan, van J.A.L.

    2010-01-01

    The ascomycete plant pathogen Botrytis cinerea secretes aspartic proteinase (AP) activity. Functional analysis was carried out on five aspartic proteinase genes (Bcap1-5) reported previously. Single and double mutants lacking these five genes showed neither a reduced secreted proteolytic activity, n

  9. Effect of low molecular weight organic acids on phosphorus adsorption by ferric-alum water treatment residuals.

    Science.gov (United States)

    Wang, Changhui; Wang, Ziyuan; Lin, Lu; Tian, Binghui; Pei, Yuansheng

    2012-02-15

    Effects of low molecular weight organic acids (LMWOAs; citric acid, oxalic acid and tartaric acid) on phosphorus (P) adsorption by ferric-alum water treatment residuals (FARs) were studied. Both batch and column experiments indicated that the effects of LMWOAs on P adsorption were closely related to adsorption time. Initially, all acids presented inhibitory function on P adsorption. The inhibition became weaker with time, eventually promoting P adsorption for citric acid and tartaric acid. In the column experiment with a 61-day duration, high P adsorption rates (>55%) were observed for the test groups containing citric acid and tartaric acid. Interestingly, higher pH likely enhanced P adsorption with the effects of LMWOAs and a distinct relationship between LMWOAs' effects on P adsorption and their concentrations was not observed. Moreover, fractionation of the adsorbed P from the FARs demonstrated that oxalic acid reduced P adsorption capacity, while citric acid and tartaric acid increased. Based on the forms of Fe and Al existing in the FARs and Fourier transform infrared spectroscopy analyses, LMWOAs can promote P adsorption through activating crystalline Fe/Al and preventing crystallization of amorphous Fe/Al to increase P adsorption sites, and can also inhibit P adsorption by competition with adsorption sites.

  10. 柠檬酸改性糠醛渣的制备%Preparation of Modified Furfural Residue With Citric Acid

    Institute of Scientific and Technical Information of China (English)

    王昕; 邢琦; 任广军

    2014-01-01

    The preparation process of modified furfural residue with citric acid was studied as well as the optimum conditions for modification. The furfural residue was first pretreated, then it was treated by 20%isopropanol and 20%sodium hydroxide solution, at last the furfural residue was modified by citric acid to obtain the citric acid modified furfural residue. Effects of reaction time, reaction temperature, citric acid solution concentration, ratio of solid to liquid on the modification were investigated. The results show that,the best modification conditions are as follows:reaction time 60 min, reaction temperature 80 ℃, citric acid concentration 100 g/L, ratio of solid to liquid 1︰4. The modified furfural residue has good adsorption for methylene blue solution, removal rate can reach to 98.2%.%研究了柠檬酸改性糠醛渣的制备过程和条件。首先对糠醛渣进行预处理,然后分别用20%的异丙醇和20%的氢氧化钠溶液处理,最后用柠檬酸对其进行改性,得到柠檬酸改性糠醛渣。讨论了反应时间,反应温度,柠檬酸溶液浓度,固液比等因素对改性的影响。结果表明:当反应时间60 min,反应温度80℃,柠檬酸质量浓度100 g/L,固液比1︰3时获得的改性糠醛渣吸附亚甲基蓝效果最好,去除率可达到98.2%。

  11. The cleavage specificity of the aspartic protease of cocoa beans involved in the generation of the cocoa-specific aroma precursors.

    Science.gov (United States)

    Janek, Katharina; Niewienda, Agathe; Wöstemeyer, Johannes; Voigt, Jürgen

    2016-11-15

    Particular peptides generated from the vicilin-class(7S) globulin of the cocoa beans by acid-induced proteolysis during cocoa fermentation are essential precursors of the cocoa-specific aroma notes. As revealed by in vitro studies, the formation of the cocoa-specific aroma precursors depends on the particular cleavage specificity of the cocoa aspartic protease, which cannot be substituted by pepsin. Therefore, we have investigated the effects of aspartic protease inhibitors on both enzymes and comparatively studied their cleavage specificities using different protein substrates and MALDI-TOF mass spectrometric analyses of the generated oligopeptides. Three classes of cleavage sites have been identified and characterized: (I) sequences exclusively cleaved by the cocoa enzyme, (II) sequences cleaved by both pepsin and the cocoa enzyme, and (III) those cleaved exclusively by pepsin. In contrast to most aspartic proteases from other origins, basic amino acid residues, particularly lysine, were found to be abundant in the specific cleavage sites of the cocoa enzyme. PMID:27283639

  12. Topology of AspT, the Aspartate:Alanine Antiporter of Tetragenococcus halophilus, Determined by Site-Directed Fluorescence Labeling▿ †

    Science.gov (United States)

    Nanatani, Kei; Fujiki, Takashi; Kanou, Kazuhiko; Takeda-Shitaka, Mayuko; Umeyama, Hideaki; Ye, Liwen; Wang, Xicheng; Nakajima, Tasuku; Uchida, Takafumi; Maloney, Peter C.; Abe, Keietsu

    2007-01-01

    The gram-positive lactic acid bacterium Tetragenococcus halophilus catalyzes the decarboxylation of l-aspartate (Asp) with release of l-alanine (Ala) and CO2. The decarboxylation reaction consists of two steps: electrogenic exchange of Asp for Ala catalyzed by an aspartate:alanine antiporter (AspT) and intracellular decarboxylation of the transported Asp catalyzed by an l-aspartate-β-decarboxylase (AspD). AspT belongs to the newly classified aspartate:alanine exchanger family (transporter classification no. 2.A.81) of transporters. In this study, we were interested in the relationship between the structure and function of AspT and thus analyzed the topology by means of the substituted-cysteine accessibility method using the impermeant, fluorescent, thiol-specific probe Oregon Green 488 maleimide (OGM) and the impermeant, nonfluorescent, thiol-specific probe [2-(trimethylammonium)ethyl]methanethiosulfonate bromide. We generated 23 single-cysteine variants from a six-histidine-tagged cysteineless AspT template. A cysteine position was assigned an external location if the corresponding single-cysteine variant reacted with OGM added to intact cells, and a position was assigned an internal location if OGM labeling required cell lysis. The topology analyses revealed that AspT has a unique topology; the protein has 10 transmembrane helices (TMs), a large hydrophilic cytoplasmic loop (about 180 amino acids) between TM5 and TM6, N and C termini that face the periplasm, and a positively charged residue (arginine 76) within TM3. Moreover, the three-dimensional structure constructed by means of the full automatic modeling system indicates that the large hydrophilic cytoplasmic loop of AspT possesses a TrkA_C domain and a TrkA_C-like domain and that the three-dimensional structures of these domains are similar to each other even though their amino acid sequences show low similarity. PMID:17660287

  13. Influence of shear force on floc properties and residual aluminum in humic acid treatment by nano-Al{sub 13}

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Weiying, E-mail: stu_xuwy@ujn.edu.cn [School of Resources and Environmental Sciences, University of Jinan, Ji’nan 250022, Shandong (China); Gao, Baoyu [Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Ji’nan 250100, Shandong (China); Du, Bin; Xu, Zhenghe; Zhang, Yongfang; Wei, Dong [School of Resources and Environmental Sciences, University of Jinan, Ji’nan 250022, Shandong (China)

    2014-04-01

    Graphical abstract: Effect of shear forces on total residual Al and dissolved residual Al in humic acid coagulations by PACl and Al{sub 13} at dosages of 5.5 mg/L. Fig. a Variations of total residual Al concentrations with shear force. Fig. b Variations of dissolved residual Al concentrations with shear force. - Highlights: • Increased shear reduced floc size, strength and re-growth but improved floc D{sub f}. • HA-Al{sub 13} flocs were smaller but showed higher S{sub f}, R{sub f} and D{sub f} than HA-PACl flocs. • Higher shear resulted in higher residual Al in finished water. • Residual Al increased less with enhanced shear rate for Al{sub 13} than that for PACl. • Higher S{sub f} and R{sub f} mitigated residual Al increment but D{sub f} had little effect on it. - Abstract: The impacts of various shear forces on floc sizes and structures in humic acid coagulations by polyaluminum chloride (PACl) and nano-Al{sub 13} were comparatively studied in this paper. The dynamic floc size was monitored by use of a laser diffraction particle sizing device. The floc structure was evaluated in terms of fractal dimension, analyzed by small-angle laser light scattering (SALLS). The effect of increased shear rate on residual Al of the coagulation effluents was then analyzed on the basis of different floc characteristics generated under various shear conditions. The results showed that floc size decreased with the increasing shear rate for both Al{sub 13} and PACl. Besides, floc strength and re-formation ability were also weakened by the enhanced shear force. Al{sub 13} resulted in small, strong and better recoverable flocs than PACl and moreover, in the shear range of 100–300 revolution per minute (rpm) (G = 40.7–178.3 s{sup −1}), the characteristics of HA-Al{sub 13} flocs displayed smaller scale changes than those of HA-PACl flocs. The results of residual Al measurements proved that with shear increased, the residual Al increased continuously but Al{sub 13

  14. A kinetic model for the competitive reactions of ozone with amino acid residues in proteins in reverse micelles

    Energy Technology Data Exchange (ETDEWEB)

    Pryor, W.A.; Uppu, R.M. (Louisiana State Univ., Baton Rouge (United States))

    1993-02-15

    Lysozyme and 10 other proteins are solubilized in reverse micelles formed by 0.1 M sodium di-2-ethyl-hexylsulfosuccinate and 2.0-2.5 M water (pH 7.4) in isooctane solvent. Exposure of the protein-containing reverse micellar solutions to ozone causes oxidative damage to the proteins, as assessed by the oxidation of tryptophan residues. The oxidation product of the protein-bound tryptophan has a molar absorption coefficient of 3275 +/- 81 M-1 cm-1 (mean +/- S.D., n = 6) at 320 nm. The product is suggested to be a Criegee ozonide or a tautomer of the Criegee ozonide and not N-formylkynurenine. Ozonation of lysozyme in reverse micelles results in the formation of hydrogen peroxide in yields of only approximately 0.07 mol/mol of tryptophan residues oxidized. The recovery of hydrogen peroxide added as an internal standard to the lysozyme-containing reverse micellar solutions ranges from 84 to 88%, whether or not the samples are subjected to ozonation. This suggests that hydrogen peroxide is neither destroyed during the process of ozonation nor consumed by the protein to a significant extent in an adventitious reaction. A kinetic model for the overall reaction of ozone with the proteins is developed, taking into account the concentrations and the reactivities of individual amino acid residues toward ozone. The model predicts the fractional reaction of ozone with tryptophan residues in the proteins, despite differences in amino acid composition, molecular weight, and tertiary structures. The lack of influence of protein structure is confirmed further by the observation that the native lysozyme (with and without external S-carboxymethylcysteine) and S-carboxymethylated lysozyme give identical values of the fractional reaction of ozone with tryptophan residues. The kinetic equations for the competitive reactions of ozone with amino acid residues in proteins, with some minor modification, are applicable to ozonations on complex mixtures of lipids, proteins, and antioxidants.

  15. Acidic Residues Control the Dimerization of the N-terminal Domain of Black Widow Spiders’ Major Ampullate Spidroin 1

    Science.gov (United States)

    Bauer, Joschka; Schaal, Daniel; Eisoldt, Lukas; Schweimer, Kristian; Schwarzinger, Stephan; Scheibel, Thomas

    2016-01-01

    Dragline silk is the most prominent amongst spider silks and comprises two types of major ampullate spidroins (MaSp) differing in their proline content. In the natural spinning process, the conversion of soluble MaSp into a tough fiber is, amongst other factors, triggered by dimerization and conformational switching of their helical amino-terminal domains (NRN). Both processes are induced by protonation of acidic residues upon acidification along the spinning duct. Here, the structure and monomer-dimer-equilibrium of the domain NRN1 of Latrodectus hesperus MaSp1 and variants thereof have been investigated, and the key residues for both could be identified. Changes in ionic composition and strength within the spinning duct enable electrostatic interactions between the acidic and basic pole of two monomers which prearrange into an antiparallel dimer. Upon naturally occurring acidification this dimer is stabilized by protonation of residue E114. A conformational change is independently triggered by protonation of clustered acidic residues (D39, E76, E81). Such step-by-step mechanism allows a controlled spidroin assembly in a pH- and salt sensitive manner, preventing premature aggregation of spider silk proteins in the gland and at the same time ensuring fast and efficient dimer formation and stabilization on demand in the spinning duct. PMID:27681031

  16. Engineering of the aspartate family biosynthetic pathway in barley (Hordeum vulgare L.) by transformation with heterologous genes encoding feed-back-insensitive aspartate kinase and dihydrodipicolinate synthase

    DEFF Research Database (Denmark)

    Brinch-Pedersen, Henrik; Galili, G; Knudsen, S;

    1996-01-01

    In prokaryotes and plants the synthesis of the essential amino acids lysine and threonine is predominantly regulated by feed-back inhibition of aspartate kinase (AK) and dihydrodipicolinate synthase (DHPS). In order to modify the flux through the aspartate family pathway in barley and enhance the...

  17. Sample Preparation for Headspace GC Analysis of Residual Solvents in Hyaluronic Acid Derivative Fiber

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hoon Joo; Kim, Dong Min; Yang, Jeong Soo [LG life Sciences, Ltd./R and D Park, Daejeon (Korea, Republic of); Kim, Chan Wha [Korea University, Seoul (Korea, Republic of)

    2006-02-15

    The aim of this study is to develop efficient sample preparation method for HS-GC analysis of residual solvents in HA derivative fiber. Compared to direct extraction of residual solvents from HA derivative fiber, the extraction through the hydrolysis of HA derivative fiber by HAse gave more complete and higher reproducible quantification of residual solvent. To validate HS-GC analysis method of residual solvents, specificity, limits of detection and quantification, linearity, accuracy and precision are investigated in the study. HA derivative fiber was hydrolyzed using HAse for headspace gas chromatographic analysis of residual solvents of ethanol, acetone and isopropanol in HA derivative fiber. This study showed that the developed method had specificity, linearity, accuracy and precision. In addition, it demonstrated that HS-GC coupled with matrix-breaking method such as hydrolysis was available for the determination of residual solvents in a matrix like HA derivative fiber.

  18. Aspartate inhibits Staphylococcus aureus biofilm formation.

    Science.gov (United States)

    Yang, Hang; Wang, Mengyue; Yu, Junping; Wei, Hongping

    2015-04-01

    Biofilm formation renders Staphylococcus aureus highly resistant to conventional antibiotics and host defenses. Four D-amino acids (D-Leu, D-Met, D-Trp and D-Tyr) have been reported to be able to inhibit biofilm formation and disassemble established S. aureus biofilms. We report here for the first time that both D- and L-isoforms of aspartate (Asp) inhibited S. aureus biofilm formation on tissue culture plates. Similar biofilm inhibition effects were also observed against other staphylococcal strains, including S. saprophyticus, S. equorum, S. chromogenes and S. haemolyticus. It was found that Asp at high concentrations (>10 mM) inhibited the growth of planktonic N315 cells, but at subinhibitory concentrations decreased the cellular metabolic activity without influencing cell growth. The decreased cellular metabolic activity might be the reason for the production of less protein and DNA in the matrix of the biofilms formed in the presence of Asp. However, varied inhibition efficacies of Asp were observed for biofilms formed by clinical staphylococcal isolates. There might be mechanisms other than decreasing the metabolic activity, e.g. the biofilm phenotypes, affecting biofilm formation in the presence of Asp.

  19. Aspartate inhibits Staphylococcus aureus biofilm formation.

    Science.gov (United States)

    Yang, Hang; Wang, Mengyue; Yu, Junping; Wei, Hongping

    2015-04-01

    Biofilm formation renders Staphylococcus aureus highly resistant to conventional antibiotics and host defenses. Four D-amino acids (D-Leu, D-Met, D-Trp and D-Tyr) have been reported to be able to inhibit biofilm formation and disassemble established S. aureus biofilms. We report here for the first time that both D- and L-isoforms of aspartate (Asp) inhibited S. aureus biofilm formation on tissue culture plates. Similar biofilm inhibition effects were also observed against other staphylococcal strains, including S. saprophyticus, S. equorum, S. chromogenes and S. haemolyticus. It was found that Asp at high concentrations (>10 mM) inhibited the growth of planktonic N315 cells, but at subinhibitory concentrations decreased the cellular metabolic activity without influencing cell growth. The decreased cellular metabolic activity might be the reason for the production of less protein and DNA in the matrix of the biofilms formed in the presence of Asp. However, varied inhibition efficacies of Asp were observed for biofilms formed by clinical staphylococcal isolates. There might be mechanisms other than decreasing the metabolic activity, e.g. the biofilm phenotypes, affecting biofilm formation in the presence of Asp. PMID:25687923

  20. A complete enzymatic recovery of ferulic acid from corn residues with extracellular enzymes from Neosartorya spinosa NRRL185.

    Science.gov (United States)

    Shin, Hyun-Dong; McClendon, Shara; Le, Tien; Taylor, Frank; Chen, Rachel Ruizhen

    2006-12-20

    An economic ferulic acid recovery from biomass via biological methods is of interest for a number of reasons. Ferulic acid is a precursor to vanillin synthesis. It is also a known antioxidant with potential food and medical applications. Despite its universal presence in all plant cell wall material, the complex structure of the plant cell wall makes ferulic acid recovery from biomass a challenging bioprocess. Previously, without pretreatment, very low (3-13%) recovery of ferulic acid from corn residues was achieved. We report here the discovery of a filamentous fungus Neosartorya spinosa NRRL185 capable of producing a full complement of enzymes to release ferulic acid and the development of an enzymatic process for a complete recovery of ferulic acid from corn bran and corn fibers. A partial characterization of the extracellular proteome of the microbe revealed the presence of at least seven cellulases and hemicellulases activities, including multiple iso-forms of xylanase and ferulic acid esterase. The recovered ferulic acid was bio-converted to vanillin, demonstrating its potential application in natural vanillin synthesis. The enzymatic ferulic acid recovery accompanied a significant release of reducing sugars (76-100%), suggesting much broader applications of the enzymes and enzyme mixtures from this organism.

  1. Determination of residues in honey after treatments with formic and oxalic acid under field conditions

    OpenAIRE

    Bogdanov, Stefan; Charrière, Jean-Daniel; IMDORF, Anton; KILCHENMANN, Verena; Fluri, Peter

    2002-01-01

    International audience Formic acid and oxalic acid field trials for control of Varroa destructor were carried out in autumn according to the Swiss prescriptions during three successive years in different apiaries in Switzerland. The following parameters were determined in honey that was harvested the year after treatment: formic acid, oxalic acid and free acidity. The following range of values were found in honeys of untreated colonies: formic acid, from 17 to 284 mg/kg, n = 34; oxalic aci...

  2. Aspartic proteinases in the digestive tract of marine decapod crustaceans.

    Science.gov (United States)

    Navarrete del Toro, María de Los Angeles; García-Carreño, Fernando; López, Manuel Díaz; Celis-Guerrero, Laura; Saborowski, Reinhard

    2006-08-01

    Decapod crustaceans synthesize highly active proteolytic enzymes in the midgut gland and release at least a part of them into the stomach where they facilitate the first step in peptide hydrolysis. The most common proteinases in the gastric fluid characterized so far are serine proteinases, that is, trypsin and chymotrypsin. These enzymes show highest activities at neutral or slightly alkaline conditions. The presence of acid proteinases, as they prevail in vertebrates, has been discussed contradictorily yet in invertebrates. In this study, we show that acid aspartic proteinases appear in the gastric fluid of several decapods. Lobsters Homarus gammarus showed the highest activity with a maximum at pH 3. These activities were almost entirely inhibited by pepstatin A, which indicates a high share of aspartic proteinases. In other species (Panulirus interruptus, Cancer pagurus, Callinectes arcuatus and Callinectes bellicosus), proteolytic activities were present at acid conditions but were distinctly lower than in H. gammarus. Zymograms at pH 3 showed in each of the studied species at least one, but mostly two-four bands of activity. The apparent molecular weight of the enzymes ranged from 17.8 to 38.6 kDa. Two distinct bands were identified which were inhibited by pepstatin A. Acid aspartic proteinases may play an important role in the process of extracellular digestion in decapod crustaceans. Activities were significantly higher in clawed lobster than in spiny lobster and three species of brachyurans. Therefore, it may be suggested that the expression of acid proteinases is favored in certain groups and reduced in others. PMID:16788916

  3. Frequencies of amino acid strings in globular protein sequences indicate suppression of blocks of consecutive hydrophobic residues

    OpenAIRE

    Schwartz, Russell; Istrail, Sorin; King, Jonathan

    2001-01-01

    Patterns of hydrophobic and hydrophilic residues play a major role in protein folding and function. Long, predominantly hydrophobic strings of 20–22 amino acids each are associated with transmembrane helices and have been used to identify such sequences. Much less attention has been paid to hydrophobic sequences within globular proteins. In prior work on computer simulations of the competition between on-pathway folding and off-pathway aggregate formation, we found that long sequences of cons...

  4. Discrimination between acid and alkali-labile phosphorylated residues on Immobilon: phosphorylation studies of nucleoside diphosphate kinase

    DEFF Research Database (Denmark)

    Biondi, R M; Walz, K; Issinger, O G;

    1996-01-01

    kinase cellular function, signaling the suppression of metastasis in the case of human NDP kinase A. Using this improved method, we show that human, Escherichia coli and Candida albicans NDP kinases are only autophosphorylated on histidine residues. In addition, we present evidence that the presence...... of phosphoserine after strong acid hydrolysis of the histidine autophosphorylated enzyme is in fact a nonenzymatic transphosphorylation from phosphohistidine due to the harsh acid treatment. This methodology was also applied to in vivo phosphorylation studies of C. albicans NDP kinase. We believe...

  5. Screening of aspartate dehydrogenase of bacteria

    OpenAIRE

    Fukuda, Shoko; Okamura, Tokumitsu; Yasumasa, Izumi; Takeno, Tomomi; Ohsugi, Masahiro

    2001-01-01

    Fifty-two strains of bacteria cultured under aerobic conditions and 12 strains of bacteria cultured under anaerobic conditions demonstrated high activity staining of aspartate dehydrogenase with NAD^+. Four strains of bacteria cultured under aerobic conditions and 7 strains of bacteria cultured under anaerobic conditions demonstrated high activity staining of aspartate dehydrogenase with NADP^+. Seven strains of bacteria cultured under aerobic conditions and 4 strains of bacteria cultured und...

  6. Synthesis of two hyaluronic-acid-related oligosaccharide 4-methoxyphenyl glycosides having a beta-D-glucuronic acid residue at the reducing end

    NARCIS (Netherlands)

    Halkes, K.M.; Slaghek, T.M.; Hypponen, T.K.; Kamerling, J.P.; Vliegenthart, J.F.G.

    1999-01-01

    Synthesis of two hyaluronic-acid-related oligosaccharides, the 4-methoxyphenyl β-glycosides of β-D-GlcpA-(1→3)-β-D-GlcpNAc-(1→4)-D-GlcpA and β-D-GlcpA-(1→3)-β-D-GlcpNAc-(1→4)-β-D-GlcpA-(1→3)- β-D-GJcpNAc-(1→4)-D-GlcpA, is described. D-Glucopyranosyluronic acid residues were obtained by selective oxi

  7. Amino acid residues important for substrate specificity of the amino acid permeases Can I p and Gnp I p in Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Regenberg, Birgitte; Kielland-Brandt, M.C.

    2001-01-01

    in the arginine permease gene CAN1. One similar mutation was found in the glutamine-asparagine permease gene GNP1. L-[C-14]citrulline uptake measurements confirmed that suppressor mutations in CAN1 conferred uptake of this amino acid, while none of the mutant permeases had lost the ability to transport L-[C-14......]arginine. Substrate specificity seemed to remain narrow in most cases, and broad substrate specificity was only observed in the cases where mutations affect two proline residues (P148 and P313) that are both conserved in the amino acid-polyamine-choline (APC) transporter superfamily. We found mutations...

  8. Chapter 4. Uranium extraction technology from wastes of uranium industry. 4.1. Sulfuric acid leaching kinetics of residues from anthropogenic deposit Map 1-9

    International Nuclear Information System (INIS)

    Present article is devoted to sulfuric acid leaching kinetics of residues from anthropogenic deposit Map 1-9. Since residues from anthropogenic deposit Map 1-9 basically contain quartz (69%), it went through acid leaching. Results of laboratory investigations on the opening degree and uranium conversion to solution were summarized. The influence of sulfuric acid consumption on uranium extraction during leaching (U = 0,018%, t =20 deg C, t = 10 hours) was considered. The kinetic and energetic parameters of residues leaching of anthropogenic deposit Map 1-9 was discussed. The basic process flow diagram of uranium industry wastes reprocessing was proposed.

  9. Basic amino acid residues located in the N-terminal region of BEND3 are essential for its nuclear localization

    International Nuclear Information System (INIS)

    BEN domain-containing protein 3 (BEND3) has recently been reported to function as a heterochromatin-associated protein in transcriptional repression in the nucleus. BEND3 should have nuclear localization signals (NLSs) to localize to the nucleus in light of its molecular weight, which is higher than that allowed to pass through nuclear pore complexes. We here analyzed the subcellular localization of deletion/site-directed mutants of human BEND3 by an immunofluorescence assay in an attempt to identify the amino acids essential for its nuclear localization. We found that three basic amino acid residues located in the N-terminal region of BEND3 (BEND356–58, KRK) are essential, suggesting that these residues play a role as a functional NLS. These results provide valuable information for progressing research on BEND3. - Highlights: • BEND3 localizes to the nucleus. • The N-terminal 60 amino acids region of BEND3 contains NLS. • Amino acids located between 56 and 58 of BEND3 (KRK) are part of NLS. • KRK motif is highly conserved among BEND3 homologs

  10. Urea, glycolic acid, and glycerol in an organic residue produced by ultraviolet irradiation of interstellar/pre-cometary ice analogs.

    Science.gov (United States)

    Nuevo, Michel; Bredehöft, Jan Hendrik; Meierhenrich, Uwe J; d'Hendecourt, Louis; Thiemann, Wolfram H-P

    2010-03-01

    More than 50 stable organic molecules have been detected in the interstellar medium (ISM), from ground-based and onboard-satellite astronomical observations, in the gas and solid phases. Some of these organics may be prebiotic compounds that were delivered to early Earth by comets and meteorites and may have triggered the first chemical reactions involved in the origin of life. Ultraviolet irradiation of ices simulating photoprocesses of cold solid matter in astrophysical environments have shown that photochemistry can lead to the formation of amino acids and related compounds. In this work, we experimentally searched for other organic molecules of prebiotic interest, namely, oxidized acid labile compounds. In a setup that simulates conditions relevant to the ISM and Solar System icy bodies such as comets, a condensed CH(3)OH:NH(3) = 1:1 ice mixture was UV irradiated at approximately 80 K. The molecular constituents of the nonvolatile organic residue that remained at room temperature were separated by capillary gas chromatography and identified by mass spectrometry. Urea, glycolic acid, and glycerol were detected in this residue, as well as hydroxyacetamide, glycerolic acid, and glycerol amide. These organics are interesting target molecules to be searched for in space. Finally, tentative mechanisms of formation for these compounds under interstellar/pre-cometary conditions are proposed.

  11. Multiple roles of the extracellular vestibule amino acid residues in the function of the rat P2X4 receptor.

    Directory of Open Access Journals (Sweden)

    Milos B Rokic

    Full Text Available The binding of ATP to trimeric P2X receptors (P2XR causes an enlargement of the receptor extracellular vestibule, leading to opening of the cation-selective transmembrane pore, but specific roles of vestibule amino acid residues in receptor activation have not been evaluated systematically. In this study, alanine or cysteine scanning mutagenesis of V47-V61 and F324-N338 sequences of rat P2X4R revealed that V49, Y54, Q55, F324, and G325 mutants were poorly responsive to ATP and trafficking was only affected by the V49 mutation. The Y54F and Y54W mutations, but not the Y54L mutation, rescued receptor function, suggesting that an aromatic residue is important at this position. Furthermore, the Y54A and Y54C receptor function was partially rescued by ivermectin, a positive allosteric modulator of P2X4R, suggesting a rightward shift in the potency of ATP to activate P2X4R. The Q55T, Q55N, Q55E, and Q55K mutations resulted in non-responsive receptors and only the Q55E mutant was ivermectin-sensitive. The F324L, F324Y, and F324W mutations also rescued receptor function partially or completely, ivermectin action on channel gating was preserved in all mutants, and changes in ATP responsiveness correlated with the hydrophobicity and side chain volume of the substituent. The G325P mutant had a normal response to ATP, suggesting that G325 is a flexible hinge. A topological analysis revealed that the G325 and F324 residues disrupt a β-sheet upon ATP binding. These results indicate multiple roles of the extracellular vestibule amino acid residues in the P2X4R function: the V49 residue is important for receptor trafficking to plasma membrane, the Y54 and Q55 residues play a critical role in channel gating and the F324 and G325 residues are critical for vestibule widening.

  12. Investigation of a substrate-specifying residue within Papaver somniferum and Catharanthus roseus aromatic amino acid decarboxylases.

    Science.gov (United States)

    Torrens-Spence, Michael P; Lazear, Michael; von Guggenberg, Renee; Ding, Haizhen; Li, Jianyong

    2014-10-01

    Plant aromatic amino acid decarboxylases (AAADs) catalyze the decarboxylation of aromatic amino acids with either benzene or indole rings. Because the substrate selectivity of AAADs is intimately related to their physiological functions, primary sequence data and their differentiation could provide significant physiological insights. However, due to general high sequence identity, plant AAAD substrate specificities have been difficult to identify through primary sequence comparison. In this study, bioinformatic approaches were utilized to identify several active site residues within plant AAAD enzymes that may impact substrate specificity. Next a Papaver somniferum tyrosine decarboxylase (TyDC) was selected as a model to verify our putative substrate-dictating residues through mutation. Results indicated that mutagenesis of serine 372 to glycine enables the P. somniferum TyDC to use 5-hydroxytryptophan as a substrate, and reduces the enzyme activity toward 3,4-dihydroxy-L-phenylalanine (dopa). Additionally, the reverse mutation in a Catharanthus roseus tryptophan decarboxylase (TDC) enables the mutant enzyme to utilize tyrosine and dopa as substrates with a reduced affinity toward tryptophan. Molecular modeling and molecular docking of the P. somniferum TyDC and the C. roseus TDC enzymes provided a structural basis to explain alterations in substrate specificity. Identification of an active site residue that impacts substrate selectivity produces a primary sequence identifier that may help differentiate the indolic and phenolic substrate specificities of individual plant AAADs. PMID:25107664

  13. Key amino acid residues for the endo-processive activity of GH74 xyloglucanase.

    Science.gov (United States)

    Matsuzawa, Tomohiko; Saito, Yuji; Yaoi, Katsuro

    2014-05-01

    Unlike endo-dissociative-xyloglucanases, Paenibacillus XEG74 is an endo-processive xyloglucanase that contains four unique tryptophan residues in the negative subsites (W61 and W64) and the positive subsites (W318 and W319), as indicated by three-dimensional homology modelling. Selective replacement of the positive subsite residues with alanine mutations reduced the degree of processive activity and resulted in the more endo-dissociative-activity. The results showed that W318 and W319, which are found in the positive subsites, are essential for processive degradation and are responsible for maintaining binding interactions with xyloglucan polysaccharide through a stacking effect. PMID:24657616

  14. Asthma induction in mice leads to appearance of alpha2-3- and alpha2-6-linked sialic acid residues in respiratory goblet-like cells

    DEFF Research Database (Denmark)

    Kirkeby, Svend; Jensen, Niels-Erik Viby; Mandel, Ulla;

    2008-01-01

    Allergic asthmatic inflammation in mice was induced by sensitization with ovalbumin and lipopolysaccharide from Escherichia coli and visualized in the airways of asthmatic mice by spatial and temporal changes of carbohydrates containing sialic acid residues. Immunohistochemistry was used to demon...

  15. Amino acid residues involved in ligand preference of the Snf3 transporter-like sensor in Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Dietvorst, J.; Karhumaa, Kaisa; Kielland-Brandt, Morten;

    2010-01-01

    -methylglucoside and 6-deoxyglucose. The signalling proficiency of a non-phosphorylatable analogue strongly supports the notion that sensing through Snf3 does not require sugar phosphorylation. Sequence comparisons of Snf3 to glucose transporters indicated amino acid residues possibly involved in sensing of sugars other...... than glucose. By site-specific mutagenesis of the structural gene, roles of specific residues in Snf3 could he established. Change of isoleucine-374 to valine ill transmembrane segment 7 of Snf3 partially abolished sensing of fructose mannose. while mutagenesis causing it change of phenylalanine-462 (4......) tyrosine ill transmembrane segment 10 of Snf3 abolished sensing of fructose. Neither of these amino :kill changes affected the ability of Snf3 to sense glucose, nor did they permit Snf3 to sense galactose. These data indicate it similarity between it ligand binding site of the sensor Snf3 and binding sites...

  16. Determination of Amino Acids in Edible Fungi planted with Chinese Medicine Residue%中药渣栽培食用菌中氨基酸含量的测定与分析

    Institute of Scientific and Technical Information of China (English)

    金茜; 曾启华; 李华刚; 文光均; 张素英

    2015-01-01

    研究了中药渣栽种的食用菌中氨基酸的成分及含量。食用菌样品经酸水解蛋白质技术预处理后,采用氨基酸自动分析仪进行检测分析,结果表明:中药渣栽种的食用菌中氨基酸种类齐全,氨基酸总量达21.34 g/100g,其中必需氨基酸的含量为9.01g/100g,含量最高的是亮氨酸(1.77g/100g),以后依次是缬氨酸(1.43 g/100g)、赖氨酸(1.21g/100g)、苯丙氨酸(1.18g/100g);用药渣栽种的食用菌中游离氨基酸的含量高达20.70g/100g,谷氨酸含量高达3.33g/100g,天冬氨酸达2.17g/100g,丰富多样的氨基酸的检出可为深入探讨食用菌独特的风味提供重要参考。%Components and contents of Amino Acids in edible fungi planted with Chinese medicine residue were researched in this ar-ticle. Detection and analysis were achieved by Automatic amino acid analyzer, after pretreatment of edible fungi samples, using Tech-nology of acid-hydrolysis amino acid. According to the results, the amino acids in edible fungi are very rich, totaled 21.34 g/100g, in which the content of essential amino acids were 9.01 g/100 g, such as leucine has the maximum content with 1.77g/100g;the second is valine with 1.43 g/100g;then lysine and phenylalanine with 1.21and 1.18 g/100g respectively. Free amino acids Totaled 20.70g/100g, glutamate and aspartic acid were 3.33 and2.17g/100g.It could provide very useful conference for studying the special fla-vor from the edible fungi.

  17. ASCORBIC ACID REDUCTION ON RESIDUAL ACTIVE CHLORINE IN POTABLE WATER PRIOR TO HALOCARBOXYLATE DETERMINATION

    Science.gov (United States)

    In studies on the formation of disinfection byproducts (DBPs), it is necessary to scavenge residual active (odxidizing) chlorine in order to fix the chlorination byproducts (such as haloethanoates) at a point in time . Such research projects often have distinct needs from requi...

  18. Thermodynamics of the first and second proton dissociations from aqueous L-aspartic acid and L-glutamic acid at temperatures from (278.15 to 393.15) K and at the pressure 0.35 MPa: Apparent molar heat capacities and apparent molar volumes of zwitterionic, protonated cationic, and deprotonated anionic forms at molalities from (0.002 to 1.0) mol . kg{sup -1}

    Energy Technology Data Exchange (ETDEWEB)

    Ziemer, S.P. [Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602-5700 (United States); Woolley, E.M. [Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602-5700 (United States)]. E-mail: earl_woolley@byu.edu

    2007-04-15

    We have measured the densities of aqueous solutions of L-aspartic acid, L-glutamic acid, and equimolal solutions of these two amino acids with HCl and with NaOH at temperatures 278.15 {<=} T/K {<=} 368.15, at molalities 0.002 {<=} m/mol . kg{sup -1} {<=} 1.0 as solubity of the solutes allowed, and at p = 0.35 MPa using a vibrating tube densimeter. We have also measured the heat capacities of these solutions at 278.15 {<=} T/K {<=} 393.15 and at the same m and p using a twin fixed-cell differential temperature-scanning calorimeter. We used the densities to calculate apparent molar volumes V {sub {phi}} and the heat capacities to calculate apparent molar heat capacities C {sub p,{phi}} for these solutions. We used our results and values from the literature for V {sub {phi}}(T, m) and C {sub p,{phi}}(T, m) for HCl(aq), NaOH(aq), and NaCl(aq) and the molar heat capacity change {delta}{sub r} C {sub p,m}(T, m) for ionization of water to calculate parameters for {delta}{sub r} C {sub p,m}(T, m) for the first two proton dissociations from each of the protonated aqueous cationic amino acids. We used Young's Rule and integrated these results iteratively to account for the effects of equilibrium speciation and chemical relaxation on V {sub {phi}}(T, m) and C {sub p,{phi}}(T, m). This procedure gave parameters for V {sub {phi}}(T, m) and C {sub p,{phi}}(T, m) for L-aspartinium and L-glutaminium chlorides and for monosodium L-aspartate and L-glutamate which modeled our observed results within experimental uncertainties. We report values for {delta}{sub r} C {sub p,m}, {delta}{sub r} H {sub m}, pQ {sub a}, {delta}{sub r} S {sub m}, and {delta}{sub r} V {sub m} for the first and second proton dissociations from protonated aqueous L-aspartic acid and L-glutamic acid as functions of T and m.

  19. Effects of the substitution of amino acid residues, through chemical synthesis, on the conformation and activity of antimicrobial peptides

    Directory of Open Access Journals (Sweden)

    Regina C. Adão

    2012-06-01

    Full Text Available Antimicrobial peptides make up an assorted group of molecules which contain from 12 to 50 amino acid residues and which may be produced by microorganisms, plants and animals. From the discovery that these biomolecules are lethal to bacteria, inhibiting the pathogenic organism’s growth, and are also related to innate and adapted defense mechanisms, the investigation of such molecules came to be an emergent research field, in which more than 1800 antimicrobial peptides have so far been discovered throughout the last three decades. These molecules are potential representatives of a new generation of antibiotic agents and the main motivation for such use is their activity against a wide variety of pathogens, including Gram-positive and Gram-negative bacteria as well as fungi and viruses. An important class of comprising some of these peptides may be found in anurans, from which it has been isolated, a considerable number of antimicrobial peptides with diverse sequences and structures, including linear and dimeric ones. In this work monomeric chains (CH1 e CH2 of the heterodimeric antimicrobial peptide distinctin (isolated in 1999 from Phyllomedusa distincta anurans, as well as its mutated monomers (CH1-S and CH2-S and the heterodimer itself were synthesized. The distinctin is the peptide with two chains of different sequences (Table 1 bound each other by disulfide bond from the cystein residues constituting the heterodimer. To investigate the effects on the biological activity by amino acids substitution at normal distinctin CH1 and CH2 chains, both were synthesized as well as their similar chains (CH1-S and CH2-S in which the cystein (Fig.1 a residues of each chain were changed by serin residues (Fig. 1 b. The new chains were named mutants. The synthesis was carried out in solid phase, using Fmoc strategy. The heterodimer distinctin was obtained from CH1 and CH2 chains coupling through cystein residues air oxidation. The results from HPLC

  20. Simulation of acid hydrolysis of lignocellulosic residues to fermentable sugars for bioethanol production

    Science.gov (United States)

    Sidiras, Dimitris

    2012-12-01

    The dilute acid hydrolysis of fir sawdust with sulfuric acid was undertaken in a batch reactor system (autoclave). The experimental data and reaction kinetic analysis indicate that this is a potential process for cellulose and hemicelluloses hydrolysis, due to a rapid hydrolysis reaction for acid concentration 0.045 N at 160-180°C. It was found that significant sugar degradation occurred at these conditions. The optimum conditions gave a yield of 38% total fermentable sugars. The kinetics of dilute acid hydrolysis of cellulose and hemicelluloses (polysaccharides) were simulated using four pseudo-kinetic models. The reaction rate constants were calculated in each case.

  1. KV4.3 expression and gating: S2 and S3 acidic and S4 innermost basic residues.

    Science.gov (United States)

    Skerritt, Matthew R; Campbell, Donald L

    2009-11-01

    Effects of neutralizing individual negatively charged (acidic [E,D]) and innermost positively charged (basic [K,R]) residues in transmembrane segments S2 (D230Q, E240Q), S3 (D263Q) and S4 (K299A/Q, R302A/Q) of the K(V)4.3 putative voltage sensing domain (VSD) were determined. S2 D230Q generated large macroscopic currents, depolarized steady-state activation ("a(4)") and isochronal (1 sec) inactivation ("i") relationships, and significantly accelerated kinetics of deactivation and recovery (from both macroscopic and closed state inactivation [CSI]). D230Q thus stabilized non-inactivated closed states. These effects were attributable to structural perturbations, and indicated D230 is not primarily involved in voltage sensing. Both S2 E240Q and S3 D263Q failed to generate measurable ionic currents, suggesting deletion of negative charges at these putatively more intracellular acidic positions were functionally "lethal" to macroscopic K(V)4.3 function. S4 innermost positive charge deletion mutants K299A/Q and R032A/Q generated functional currents with reduced peak amplitudes. While reduced K299A/Q and R302A/Q currents prevented accurate determination of "a(4)" and estimates of potential electrostatic perturbations, both sets of mutants: (i) depolarized potentials at which currents could be macroscopically detected, consistent with stabilization of closed states (structural perturbations); and (ii) accelerated macroscopic recovery. These results provide further evidence that: (i) basic residues in S4 are involved not only in regulating K(V)4.3 activation and deactivation, but also CSI and recovery; and (ii) suggest putative electrostatic interactions between acidic S2/S3 and basic S4 residues may be different in K(V)4.3 from those proposed to exist in Shaker. Functional implications are discussed.

  2. An acidic amino acid transmembrane helix 10 residue conserved in the neurotransmitter:sodium:symporters is essential for the formation of the extracellular gate of the γ-aminobutyric acid (GABA) transporter GAT-1.

    Science.gov (United States)

    Ben-Yona, Assaf; Kanner, Baruch I

    2012-03-01

    GAT-1 mediates transport of GABA together with sodium and chloride in an electrogenic process enabling efficient GABAergic transmission. Biochemical and modeling studies based on the structure of the bacterial homologue LeuT are consistent with a mechanism whereby the binding pocket is alternately accessible to either side of the membrane and which predicts that the extracellular part of transmembrane domain 10 (TM10) exhibits aqueous accessibility in the outward-facing conformation only. In this study we have engineered cysteine residues in the extracellular half of TM10 of GAT-1 and probed their state-dependent accessibility to sulfhydryl reagents. In three out of four of the accessible cysteine mutants, the inhibition of transport by a membrane impermeant sulfhydryl reagent was diminished under conditions expected to increase the proportion of inward-facing transporters, such as the presence of GABA together with the cotransported ions. A conserved TM10 aspartate residue, whose LeuT counterpart participates in a "thin" extracellular gate, was found to be essential for transport and only the D451E mutant exhibited residual transport activity. D451E exhibited robust sodium-dependent transient currents with a voltage-dependence indicative of an increased apparent affinity for sodium. Moreover the accessibility of an endogenous cysteine to a membrane impermeant sulfhydryl reagent was enhanced by the D451E mutation, suggesting that sodium binding promotes an outward-facing conformation of the transporter. Our results support the idea that TM10 of GAT-1 lines an accessibility pathway from the extracellular space into the binding pocket and plays a role in the opening and closing of the extracellular transporter gate.

  3. Reasoned opinion on the review of the existing maximum residue levels (MRLs for indolylacetic acid according to Article 12 of Regulation (EC No 396/2005

    Directory of Open Access Journals (Sweden)

    European Food Safety Authority

    2014-07-01

    Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance indolylacetic acid. Considering that this active substance is no longer authorised within the European Union, that no MRLs are established by the Codex Alimentarius Commission, and that no import tolerances were notified to EFSA, residues of indolylacetic acid are not expected to occur in any plant or animal commodity. Available data were also not sufficient to derive a residue definition or a limit of quantification (LOQ for enforcement against potential illegal uses.

  4. Reasoned opinion on the review of the existing maximum residue levels (MRLs for 2-naphthyloxyacetic acid according to Article 12 of Regulation (EC No 396/2005

    Directory of Open Access Journals (Sweden)

    European Food Safety Authority

    2013-07-01

    Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance 2-naphthyloxyacetic acid. Considering that this active substance is no longer authorised within the European Union, that no MRLs are established by the Codex Alimentarius Commission, and that no import tolerances were notified to EFSA, residues of 2-naphthyloxyacetic acid are not expected to occur in any plant or animal commodity. Available data were also not sufficient to derive a residue definition or an LOQ for enforcement against potential illegal uses.

  5. Reasoned opinion on the review of the existing maximum residue levels (MRLs for indolylbutyric acid according to Article 12 of Regulation (EC No 396/2005

    Directory of Open Access Journals (Sweden)

    European Food Safety Authority

    2014-07-01

    Full Text Available According to Article 12 of Regulation (EC No 396/2005, the European Food Safety Authority (EFSA has reviewed the Maximum Residue Levels (MRLs currently established at European level for the pesticide active substance indolylbutyric acid. Considering that this active substance is not authorised for use on edible crops within the European Union, that no MRLs are established by the Codex Alimentarius Commission, and that no import tolerances were notified to EFSA, residues of indolylbutyric acid are not expected to occur in any plant or animal commodity. Available data were also not sufficient to derive a residue definition or a limit of quantification (LOQ for enforcement against potential illegal uses.

  6. Molecular cloning and characterization of the pyrB1 and pyrB2 genes encoding aspartate transcarbamoylase in pea (Pisum sativum L.).

    Science.gov (United States)

    Williamson, C L; Slocum, R D

    1994-05-01

    We cloned cDNAs encoding two different pea (Pisum sativum L.) aspartate transcarbamoylases (ATCases) by complementation of an Escherichia coli delta pyrB mutant. The two cDNAs, designated pyrB1 and pyrB2, encode polypeptides of 386 and 385 amino acid residues, respectively, both of which exhibit typical chloroplast transit peptide sequences. Wheat germ ATCase antibody recognizes a 36.5-kD polypeptide in pea leaf and root tissues that is similar in size to other plant ATCase polypeptides and to the catalytic polypeptides of bacterial ATCases. Northern analyses indicate that the pyrB1 and pyrB2 transcripts are 1.6 kb in size and are differentially expressed in pea tissues. The small transcript size and data from biochemical studies indicate that plant ATCases are simple homotrimers of 36- to 37-kD catalytic subunits, rather than part of a multifunctional enzyme containing glutamine-dependent carbamoylphosphate synthetase and dihydroorotase activities, as is seen in other eukaryotes. In the pea ATCases, the carbamoylphosphate- and aspartate-binding domains are highly homologous to those of other prokaryotic and eukaryotic ATCases and critical active-site residues are completely conserved. The pea ATCases also exhibit a putative pyrimidine-binding site, consistent with the known allosteric regulation of plant ATCases by UMP in vitro. PMID:8029359

  7. Stabile Chlorine Isotope Study of Martian Shergottites and Nakhlites; Whole Rock and Acid Leachates and Residues

    Science.gov (United States)

    Nakamura, N.; Nyquist, L. E.; Reese, Y.; Shih, C-Y; Fujitani, T.; Okano, O.

    2011-01-01

    We have established a precise analytical technique for stable chlorine isotope measurements of tiny planetary materials by TIMS (Thermal Ionization Mass Spectrometry) [1], for which the results are basically consistent with the IRMS tech-nique (gas source mass spectrometry) [2,3,4]. We present here results for Martian shergottites and nakhlites; whole rocks, HNO3-leachates and residues, and discuss the chlorine isotope evolution of planetary Mars.

  8. Immobilization by Polyurethane of Pseudomonas dacunhae Cells Containing l-Aspartate β-Decarboxylase Activity and Application to l-Alanine Production

    OpenAIRE

    Fusee, Murray C.; Weber, Jennifer E.

    1984-01-01

    Whole cells of Pseudomonas dacunhae containing l-aspartate β-decarboxylase activity were immobilized by mixing a cell suspension with a liquid isocyanate-capped polyurethane prepolymer (Hypol; W. R. Grace & Co., Lexington, Mass.). The immobilized cell preparation was used to convert l-aspartic acid to l-alanine. Properties of the immobilized P. dacunhae cells containing aspartate β-decarboxylase activity were investigated with batch reactors. Retention of enzyme activity was observed to be as...

  9. Optimization of a Nucleic Acids united-RESidue 2-Point model (NARES-2P) with a maximum-likelihood approach

    International Nuclear Information System (INIS)

    Coarse-grained models are useful tools to investigate the structural and thermodynamic properties of biomolecules. They are obtained by merging several atoms into one interaction site. Such simplified models try to capture as much as possible information of the original biomolecular system in all-atom representation but the resulting parameters of these coarse-grained force fields still need further optimization. In this paper, a force field optimization method, which is based on maximum-likelihood fitting of the simulated to the experimental conformational ensembles and least-squares fitting of the simulated to the experimental heat-capacity curves, is applied to optimize the Nucleic Acid united-RESidue 2-point (NARES-2P) model for coarse-grained simulations of nucleic acids recently developed in our laboratory. The optimized NARES-2P force field reproduces the structural and thermodynamic data of small DNA molecules much better than the original force field

  10. Optimization of a Nucleic Acids united-RESidue 2-Point model (NARES-2P) with a maximum-likelihood approach

    Energy Technology Data Exchange (ETDEWEB)

    He, Yi; Scheraga, Harold A., E-mail: has5@cornell.edu [Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853 (United States); Liwo, Adam [Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk (Poland)

    2015-12-28

    Coarse-grained models are useful tools to investigate the structural and thermodynamic properties of biomolecules. They are obtained by merging several atoms into one interaction site. Such simplified models try to capture as much as possible information of the original biomolecular system in all-atom representation but the resulting parameters of these coarse-grained force fields still need further optimization. In this paper, a force field optimization method, which is based on maximum-likelihood fitting of the simulated to the experimental conformational ensembles and least-squares fitting of the simulated to the experimental heat-capacity curves, is applied to optimize the Nucleic Acid united-RESidue 2-point (NARES-2P) model for coarse-grained simulations of nucleic acids recently developed in our laboratory. The optimized NARES-2P force field reproduces the structural and thermodynamic data of small DNA molecules much better than the original force field.

  11. The role of amino acid residues in the active site of L-methionine γ-lyase from Pseudomonas putida.

    Science.gov (United States)

    Fukumoto, Mitsuki; Kudou, Daizou; Murano, Shouko; Shiba, Tomoo; Sato, Dan; Tamura, Takashi; Harada, Shigeharu; Inagaki, Kenji

    2012-01-01

    Cys116, Lys240*, and Asp241* (asterisks indicate residues from the second subunit of the active dimer) at the active site of L-methionine γ-lyase of Pseudomonas putida (MGL_Pp) are highly conserved among heterologous MGLs. In a previous study, we found that substitution of Cys116 for His led to a drastic increase in activity toward L-cysteine and a decrease in that toward L-methionine. In this study, we examined some properties of the C116H mutant by kinetic analysis and 3D structural analysis. We assumed that substitution of Cys116 for His broke the original hydrogen-bond network and that this induced a significant effect of Tyr114 as a general acid catalyst, possibly due to the narrow space in the active site. The C116H mutant acquired a novel β-elimination activity and lead a drastic conformation change in the histidine residue at position 116 by binding the substrate, suggesting that this His residue affects the reaction specificity of C116H. Furthermore, we suggest that Lys240* is important for substrate recognition and structural stability and that Asp241* is also involved in substrate specificity in the elimination reaction. Based on this, we suggest that the hydrogen-bond network among Cys116, Lys240*, and Asp241* contributes to substrate specificity that is, to L-methionine recognition at the active site in MGL_Pp.

  12. Improving volatile fatty acids production by exploiting the residual substrates in post-fermented sludge: Protease catalysis of refractory protein.

    Science.gov (United States)

    Yin, Bo; Liu, Hongbo; Wang, Yuanyuan; Bai, Jie; Liu, He; Fu, Bo

    2016-03-01

    The real cause to the low yield of volatile fatty acids (VFAs), from inhibition or low biodegradation, is uncertain in sludge anaerobic fermentation. In this study, poor biodegradability of proteins and fast decrease of the indigenous hydrolase activity in the residual post-fermented sludge were found to be the major reasons. With the addition of trypsin or alkaline protease in residual post-fermented sludge after primary alkaline fermentation, degradation efficiency of refractory protein increased by 33.6% and 34.8%, respectively. Accordingly, the VFAs yields were improved by 69.7% and 106.1%, respectively. Furthermore, the activities of added trypsin and alkaline protease could maintain at 13.52 U/mL and 19.11 U/mL in the alkaline fermentation process. This study demonstrated that exploiting the refractory proteins in residual post-fermented sludge by protease addition seems to be a very promising way for improving VFAs yield of conventional alkaline fermentations with waste activated sludge. PMID:26722812

  13. Prediction of the Residual Strength for Durability Failure of Concrete Structure in Acidic Environments

    Institute of Scientific and Technical Information of China (English)

    LI Beixing; CAI Laohu; WANG Kai; ZHANG Yaming

    2016-01-01

    According to the results of accelerated tests of acidiifcation corrosion depth and compressive strength of concretes subjected to sulfuric acid environments, the acidiifcation depth laws of concretes were predicted based on the grey system theory. Thus, the remaining compressive strength was calculated when the acidiifcation depth reached the protection layer thickness of concrete structures, which indicates that the limit state of durability failure can be deifned based on strength degradation, and the calculation process was illustrated by an example. The calculated results show that the remaining compressive strength values in the durability failure limit state for the concrete structures exposed to pH=2 and 3 sulfuric acid water environments and wet-dry cyclic sulfuric acid environment with pH=2 are 74%, 72%, and 80% of initial strength, respectively. The method provides references for the durability evaluation of concrete structure design under the acidic environments.

  14. Residual Host Cell Protein Promotes Polysorbate 20 Degradation in a Sulfatase Drug Product Leading to Free Fatty Acid Particles.

    Science.gov (United States)

    Dixit, Nitin; Salamat-Miller, Nazila; Salinas, Paul A; Taylor, Katherine D; Basu, Sujit K

    2016-05-01

    This study investigated the root cause behind an observed free fatty acid particle formation and resulting Polysorbate 20 (PS20) loss for a sulfatase drug product upon long-term storage at 5 ± 3°C. Reversed- phase chromatography with mass spectrometric analysis as well as charged aerosol detection was used to characterize the peaks associated with the intact and degraded PS20. Additionally, a proteomics study was undertaken to identify the residual host cell proteins in the sulfatase drug substance. PS20 stability studies were conducted in the presence of sulfatase, a sulfatase inhibitor, putative phospholipase B-like 2, and mock drug substance produced using a null cell line vector under experimental conditions optimized for PS20 degradation. This study provides the first published evidence where the residual host cell protein present in the drug substance was identified and experimentally shown to catalyze the breakdown of PS20 in a protein formulation over time, resulting in free fatty acid particles and PS20 loss. This study demonstrates the importance of early detection of potential impurities in the protein drug substance that may contribute to polysorbate degradation to make a judicious selection of the surfactant and its optimized concentration for the final drug product. PMID:27032893

  15. Identification of functional amino acid residues involved in polyamine and agmatine transport by human organic cation transporter 2.

    Directory of Open Access Journals (Sweden)

    Kyohei Higashi

    Full Text Available Polyamine (putrescine, spermidine and spermine and agmatine uptake by the human organic cation transporter 2 (hOCT2 was studied using HEK293 cells transfected with pCMV6-XL4/hOCT2. The Km values for putrescine and spermidine were 7.50 and 6.76 mM, and the Vmax values were 4.71 and 2.34 nmol/min/mg protein, respectively. Spermine uptake by hOCT2 was not observed at pH 7.4, although it inhibited both putrescine and spermidine uptake. Agmatine was also taken up by hOCT2, with Km value: 3.27 mM and a Vmax value of 3.14 nmol/min/mg protein. Amino acid residues involved in putrescine, agmatine and spermidine uptake by hOCT2 were Asp427, Glu448, Glu456, Asp475, and Glu516. In addition, Glu524 and Glu530 were involved in putrescine and spermidine uptake activity, and Glu528 and Glu540 were weakly involved in putrescine uptake activity. Furthermore, Asp551 was also involved in the recognition of spermidine. These results indicate that the recognition sites for putrescine, agmatine and spermidine on hOCT2 strongly overlap, consistent with the observation that the three amines are transported with similar affinity and velocity. A model of spermidine binding to hOCT2 was constructed based on the functional amino acid residues.

  16. Identifying SARS-CoV membrane protein amino acid residues linked to virus-like particle assembly.

    Directory of Open Access Journals (Sweden)

    Ying-Tzu Tseng

    Full Text Available Severe acute respiratory syndrome coronavirus (SARS-CoV membrane (M proteins are capable of self-assembly and release in the form of membrane-enveloped vesicles, and of forming virus-like particles (VLPs when coexpressed with SARS-CoV nucleocapsid (N protein. According to previous deletion analyses, M self-assembly involves multiple M sequence regions. To identify important M amino acid residues for VLP assembly, we coexpressed N with multiple M mutants containing substitution mutations at the amino-terminal ectodomain, carboxyl-terminal endodomain, or transmembrane segments. Our results indicate that a dileucine motif in the endodomain tail (218LL219 is required for efficient N packaging into VLPs. Results from cross-linking VLP analyses suggest that the cysteine residues 63, 85 and 158 are not in close proximity to the M dimer interface. We noted a significant reduction in M secretion due to serine replacement for C158, but not for C63 or C85. Further analysis suggests that C158 is involved in M-N interaction. In addition to mutations of the highly conserved 107-SWWSFNPE-114 motif, substitutions at codons W19, W57, P58, W91, Y94 or F95 all resulted in significantly reduced VLP yields, largely due to defective M secretion. VLP production was not significantly affected by a tryptophan replacement of Y94 or F95 or a phenylalanine replacement of W19, W57 or W91. Combined, these results indicate the involvement of specific M amino acids during SARS-CoV virus assembly, and suggest that aromatic residue retention at specific positions is critical for M function in terms of directing virus assembly.

  17. Influence of washing time on residual contamination of carcasses sprayed with lauric acid-potassium hydroxide.

    Science.gov (United States)

    A series of experiments were conducted to examine reductions in bacterial contamination of broiler carcasses washed for various times in a spray cabinet with a 2% lauric acid (LA)-1% potassium hydroxide (KOH) (w/v) solution. Forty eviscerated carcasses and 5 ceca were obtained from the processing l...

  18. IRMPD spectroscopy b(2) ions from protonated tripeptides with 4-aminomethyl benzoic acid residues

    NARCIS (Netherlands)

    M. J. Kullman; S. Molesworth; G. Berden; J. Oomens; M. van Stipdonk

    2012-01-01

    Collision-induced dissociation (CID) of the peptide alanine-4-aminomethylbenzoic acid-glycine, A(AMBz)G generates a prominent b2 ion despite a previous report [E.R. Talaty, T.J. Cooper, S.M. Osburn, M.J. Van Stipdonk, Collision-induced dissociation of protonated tetrapeptides containing β-alanine, γ

  19. IRMPD spectroscopy b(2) ions from protonated tripeptides with 4-aminomethyl benzoic acid residues

    NARCIS (Netherlands)

    Kullman, M. J.; Molesworth, S.; G. Berden,; Oomens, J.; Van Stipdonk, M.

    2012-01-01

    Collision-induced dissociation (CID) of the peptide alanine-4-aminomethylbenzoic acid-glycine, A(AMBz)G generates a prominent b(2) ion despite a previous report [ER. Talaty, T.J. Cooper, S.M. Osburn, M.J. Van Stipdonk, Collision-induced dissociation of protonated tetrapeptides containing beta-alanin

  20. Integration of galacturonic acid extraction with alkaline protein extraction from green tea leaf residue

    NARCIS (Netherlands)

    Zhang, Chen; Bozileva, Elvira; Klis, van der Frits; Dong, Yiyuan; Sanders, Johan P.M.; Bruins, Marieke E.

    2016-01-01

    Leaf pectin can be used as a feedstock for galacturonic acid (GA) production, but high extraction costs limit economic feasibility. To improve the extraction efficiency, leaf pectin extraction was integrated with an already cost-effective alkaline protein extraction, focusing on high yield of GA

  1. Self-assembling properties of all γ-cyclic peptides containing sugar amino acid residues.

    Science.gov (United States)

    Guerra, Arcadio; Brea, Roberto J; Amorín, Manuel; Castedo, Luis; Granja, Juan R

    2012-11-28

    In this study, a novel dimer-forming cyclic peptide composed exclusively by cyclic γ-amino acids with a saccharide-like outer surface is described. The antiparallel β-sheet type hydrogen bonding interactions responsible for the large association constant in non-polar solvents constitute a suitable model for a novel class of self-assembling peptide nanotubes.

  2. Low affinity and slow Na+-binding precedes high affinity aspartate binding in GltPh

    NARCIS (Netherlands)

    Hänelt, Inga; Jensen, Sonja; Wunnicke, Dorith; Slotboom, Dirk Jan

    2015-01-01

    GltPh from Pyrococcus horikoshii is a homotrimeric Na+-coupled aspartate transporter. It belongs to the widespread family of glutamate transporters, which also includes the mammalian excitatory amino acid transporters (EAATs) that take up the neurotransmitter glutamate. Each protomer in GltPh consis

  3. Substitution of Ala564 in the first zinc cluster of the deoxyribonucleic acid (DNA)-binding domain of the androgen receptor by Asp, Asn, or Leu exerts differential effects on DNA binding

    NARCIS (Netherlands)

    H.T. Brüggenwirth (Hennie); A.L.M. Boehmer (Annemie); J.M. Lobaccaro; L. Chiche; C. Sultan; J. Trapman (Jan); A.O. Brinkmann (Albert)

    1998-01-01

    textabstractIn the androgen receptor of a patient with androgen insensitivity, the alanine residue at position 564 in the first zinc cluster of the DNA-binding domain was substituted by aspartic acid. In other members of the steroid receptor family, either valine or ala

  4. Identification of Ourmiavirus 30K movement protein amino acid residues involved in symptomatology, viral movement, subcellular localization and tubule formation.

    Science.gov (United States)

    Margaria, Paolo; Anderson, Charles T; Turina, Massimo; Rosa, Cristina

    2016-09-01

    Several plant viruses encode movement proteins (MPs) classified in the 30K superfamily. Despite a great functional diversity, alignment analysis of MP sequences belonging to the 30K superfamily revealed the presence of a central core region, including amino acids potentially critical for MP structure and functionality. We performed alanine-scanning mutagenesis of the Ourmia melon virus (OuMV) MP, and studied the effects of amino acid substitutions on MP properties and virus infection. We identified five OuMV mutants that were impaired in systemic infection in Nicotiana benthamiana and Arabidopsis thaliana, and two mutants showing necrosis and pronounced mosaic symptoms, respectively, in N. benthamiana. Green fluorescent protein fusion constructs (GFP:MP) of movement-defective MP alleles failed to localize in distinct foci at the cell wall, whereas a GFP fusion with wild-type MP (GFP:MPwt) mainly co-localized with plasmodesmata and accumulated at the periphery of epidermal cells. The movement-defective mutants also failed to produce tubular protrusions in protoplasts isolated from infected leaves, suggesting a link between tubule formation and the ability of OuMV to move. In addition to providing data to support the importance of specific amino acids for OuMV MP functionality, we predict that these conserved residues might be critical for the correct folding and/or function of the MP of other viral species in the 30K superfamily. PMID:26637973

  5. The dissociative anaesthetics, ketamine and phencyclidine, selectively reduce excitation of central mammalian neurones by N-methyl-aspartate.

    OpenAIRE

    Anis, N. A.; Berry, S. C.; Burton, N. R.; Lodge, D.

    1983-01-01

    The interaction of two dissociative anaesthetics, ketamine and phencyclidine, with the responses of spinal neurones to the electrophoretic administration of amino acids and acetylcholine was studied in decerebrate or pentobarbitone-anaesthetized cats and rats. Both ketamine and phencyclidine selectively blocked excitation by N-methyl-aspartate (NMA) with little effect on excitation by quisqualate and kainate. Ketamine reduced responses to L-aspartate somewhat more than those of L-glutamate; t...

  6. Amino acid residues of heparin cofactor II required for stimulation of thrombin inhibition by sulphated polyanions.

    Science.gov (United States)

    Colwell, N S; Grupe, M J; Tollefsen, D M

    1999-04-12

    A variety of sulphated polyanions in addition to heparin and dermatan sulphate stimulate the inhibition of thrombin by heparin cofactor II (HCII). Previous investigations indicated that the binding sites on HCII for heparin and dermatan sulphate overlap but are not identical. In this study we determined the concentrations (IC50) of various polyanions required to stimulate thrombin inhibition by native recombinant HCII in comparison with three recombinant HCII variants having decreased affinity for heparin (Lys-173-->Gln), dermatan sulphate (Arg-189-->His), or both heparin and dermatan sulphate (Lys-185-->Asn). Pentosan polysulphate, sulphated bis-lactobionic acid amide, and sulphated bis-maltobionic acid amide resembled dermatan sulphate, since their IC50 values were increased to a much greater degree (>/=8-fold) by the mutations Arg-189-->His and Lys-185-->Asn than by Lys-173-->Gln (Gln and Lys-185-->Asn (>/=6-fold) than by Arg-189-->His (acidic domain. PMID:10209287

  7. Lead Isotope Compositions of Acid Residues from Olivine-Phyric Shergottite Tissint: Implications for Heterogeneous Shergottite Source Reservoirs

    Science.gov (United States)

    Moriwaki, R.; Usui, T.; Yokoyama, T.; Simon, J. I.; Jones, J. H.

    2015-01-01

    Geochemical studies of shergottites suggest that their parental magmas reflect mixtures between at least two distinct geochemical source reservoirs, producing correlations between radiogenic isotope compositions and trace element abundances. These correlations have been interpreted as indicating the presence of a reduced, incompatible element- depleted reservoir and an oxidized, incompatible- element-enriched reservoir. The former is clearly a depleted mantle source, but there is ongoing debate regarding the origin of the enriched reservoir. Two contrasting models have been proposed regarding the location and mixing process of the two geochemical source reservoirs: (1) assimilation of oxidized crust by mantle derived, reduced magmas, or (2) mixing of two distinct mantle reservoirs during melting. The former requires the ancient Martian crust to be the enriched source (crustal assimilation), whereas the latter requires isolation of a long-lived enriched mantle domain that probably originated from residual melts formed during solidification of a magma ocean (heterogeneous mantle model). This study conducts Pb isotope and trace element concentration analyses of sequential acid-leaching fractions (leachates and the final residues) from the geochemically depleted olivine-phyric shergottite Tissint. The results suggest that the Tissint magma is not isotopically uniform and sampled at least two geochemical source reservoirs, implying that either crustal assimilation or magma mixing would have played a role in the Tissint petrogenesis.

  8. The Loss and Gain of Functional Amino Acid Residues Is a Common Mechanism Causing Human Inherited Disease.

    Science.gov (United States)

    Lugo-Martinez, Jose; Pejaver, Vikas; Pagel, Kymberleigh A; Jain, Shantanu; Mort, Matthew; Cooper, David N; Mooney, Sean D; Radivojac, Predrag

    2016-08-01

    Elucidating the precise molecular events altered by disease-causing genetic variants represents a major challenge in translational bioinformatics. To this end, many studies have investigated the structural and functional impact of amino acid substitutions. Most of these studies were however limited in scope to either individual molecular functions or were concerned with functional effects (e.g. deleterious vs. neutral) without specifically considering possible molecular alterations. The recent growth of structural, molecular and genetic data presents an opportunity for more comprehensive studies to consider the structural environment of a residue of interest, to hypothesize specific molecular effects of sequence variants and to statistically associate these effects with genetic disease. In this study, we analyzed data sets of disease-causing and putatively neutral human variants mapped to protein 3D structures as part of a systematic study of the loss and gain of various types of functional attribute potentially underlying pathogenic molecular alterations. We first propose a formal model to assess probabilistically function-impacting variants. We then develop an array of structure-based functional residue predictors, evaluate their performance, and use them to quantify the impact of disease-causing amino acid substitutions on catalytic activity, metal binding, macromolecular binding, ligand binding, allosteric regulation and post-translational modifications. We show that our methodology generates actionable biological hypotheses for up to 41% of disease-causing genetic variants mapped to protein structures suggesting that it can be reliably used to guide experimental validation. Our results suggest that a significant fraction of disease-causing human variants mapping to protein structures are function-altering both in the presence and absence of stability disruption. PMID:27564311

  9. Determination of cyanuric acid residues in catfish, trout, tilapia, salmon and shrimp by liquid chromatography-tandem mass spectrometry

    International Nuclear Information System (INIS)

    In May 2007, investigators discovered that waste material from the pet food manufacturing process contaminated with melamine (MEL) and/or cyanuric acid (CYA) had been added to hog and chicken feeds. At this time, investigators also learned that adulterated wheat gluten had been used in the manufacture of aquaculture feeds. Concern that the contaminated feed had been used in aquaculture and could enter the human food supply prompted the development of a method for the determination of CYA residues in the edible tissues of fish and shrimp. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was employed as a sensitive technique for the analysis of CYA in catfish, tilapia, salmon, trout and shrimp tissue. CYA was extracted from ground fish or shrimp with an acetic acid solution, defatted with hexane, and isolated with a graphitic carbon black solid-phase extraction column. Residues were separated from matrix components using a porous graphitic carbon LC column, and then analyzed with electrospray ionization in negative ion mode on a triple quadrupole mass spectrometer. Selective reaction monitoring was performed on the [M-H]-m/z 128 ion resulting in the product ions m/z 85 and 42. Recoveries from catfish, tilapia and trout fortified with 10-100 μg kg-1 of CYA averaged 67% with a relative standard deviation (R.S.D.) of 18% (n = 107). The average method detection limit (MDL) for catfish, tilapia and trout is 3.5 μg kg-1. An internal standard, 13C3-labeled CYA, was used in the salmon and shrimp extractions. Average recovery of CYA from salmon was 91% (R.S.D. = 15%, n = 18) with an MDL of 7.4 μg kg-1. Average recovery of CYA from shrimp was 85% (R.S.D. = 10%, n = 13) with an MDL of 3.5 μg kg-1

  10. Differential Aspartate Usage Identifies a Subset of Cancer Cells Particularly Dependent on OGDH

    Directory of Open Access Journals (Sweden)

    Eric L. Allen

    2016-10-01

    Full Text Available Although aberrant metabolism in tumors has been well described, the identification of cancer subsets with particular metabolic vulnerabilities has remained challenging. Here, we conducted an siRNA screen focusing on enzymes involved in the tricarboxylic acid (TCA cycle and uncovered a striking range of cancer cell dependencies on OGDH, the E1 subunit of the alpha-ketoglutarate dehydrogenase complex. Using an integrative metabolomics approach, we identified differential aspartate utilization, via the malate-aspartate shuttle, as a predictor of whether OGDH is required for proliferation in 3D culture assays and for the growth of xenograft tumors. These findings highlight an anaplerotic role of aspartate and, more broadly, suggest that differential nutrient utilization patterns can identify subsets of cancers with distinct metabolic dependencies for potential pharmacological intervention.

  11. D-aspartate and NMDA, but not L-aspartate, block AMPA receptors in rat hippocampal neurons

    DEFF Research Database (Denmark)

    Gong, Xiang-Qun; Frandsen, Anne; Lu, Wei-Yang;

    2005-01-01

    to the right. Schild plot analysis indicated that D-aspartate acts competitively to block AMPARs. The K(b) for D-aspartate was estimated to be 0.93 mM. 4 D-aspartate also blocked L-glutamate-induced current in Xenopus laevis oocytes that expressed recombinant homomeric AMPARs. 5 NMDA possessed similar...

  12. Structural Insights into the Activation and Inhibition of Histo-Aspartic Protease from Plasmodium falciparum

    Energy Technology Data Exchange (ETDEWEB)

    Bhaumik, Prasenjit; Xiao, Huogen; Hidaka, Koushi; Gustchina, Alla; Kiso, Yoshiaki; Yada, Rickey Y.; Wlodawer, Alexander (Guelph); (Kyoto); (NCI)

    2012-09-17

    Histo-aspartic protease (HAP) from Plasmodium falciparum is a promising target for the development of novel antimalarial drugs. The sequence of HAP is highly similar to those of pepsin-like aspartic proteases, but one of the two catalytic aspartates, Asp32, is replaced with histidine. Crystal structures of the truncated zymogen of HAP and of the complex of the mature enzyme with inhibitor KNI-10395 have been determined at 2.1 and 2.5 {angstrom} resolution, respectively. As in other proplasmepsins, the propeptide of the zymogen interacts with the C-terminal domain of the enzyme, forcing the N- and C-terminal domains apart, thereby separating His32 and Asp215 and preventing formation of the mature active site. In the inhibitor complex, the enzyme forms a tight domain-swapped dimer, not previously seen in any aspartic proteases. The inhibitor is found in an unprecedented conformation resembling the letter U, stabilized by two intramolecular hydrogen bonds. Surprisingly, the location and conformation of the inhibitor are similar to those of the fragment of helix 2 comprising residues 34p-38p in the prosegments of the zymogens of gastric aspartic proteases; a corresponding helix assumes a vastly different orientation in proplasmepsins. Each inhibitor molecule is in contact with two molecules of HAP, interacting with the carboxylate group of the catalytic Asp215 of one HAP protomer through a water molecule, while also making a direct hydrogen bond to Glu278A' of the other protomer. A comparison of the shifts in the positions of the catalytic residues in the inhibitor complex presented here with those published previously gives further hints regarding the enzymatic mechanism of HAP.

  13. ACID EVAPORATION OF ULTIMA GOLD TM AB LIQUID SCINTILLATION COCKTAIL RESIDUE

    Energy Technology Data Exchange (ETDEWEB)

    Kyser, E.; Fondeur, F.; Crump, S.

    2011-12-21

    Prior analyses of samples from the F/H Lab solutions showed the presence of diisopropylnapthalene (DIN), a major component of Ultima Gold{trademark} AB liquid scintillation cocktail (LSC). These solutions are processed through H-Canyon Tank 10.5 and ultimately through the 17.8E evaporator. Similar solutions originated in SRNL streams sent to the same H Canyon tanks. This study examined whether the presence of these organics poses a process-significant hazard for the evaporator. Evaporation and calorimetry testing of surrogate samples containing 2000 ppm of Ultima Gold{trademark} AB LSC in 8 M nitric acid have been completed. These experiments showed that although reactions between nitric acid and the organic components do occur, they do not appear to pose a significant hazard for runaway reactions or generation of energetic compounds in canyon evaporators. The amount of off-gas generated was relatively modest and appeared to be well within the venting capacity of the H-Canyon evaporators. A significant fraction of the organic components likely survives the evaporation process primarily as non-volatile components that are not expected to represent any new process concerns during downstream operations such as neutralization. Laboratory Waste solutions containing minor amounts of DIN can be safely received, stored, transferred, and processed through the canyon waste evaporator.

  14. Dilute Sulfuric Acid Pretreatment of Agricultural and Agro-Industrial Residues for Ethanol Production

    Science.gov (United States)

    Martin, Carlos; Alriksson, Björn; Sjöde, Anders; Nilvebrant, Nils-Olof; Jönsson, Leif J.

    The potential of dilute-acid prehydrolysis as a pretreatment method for sugarcane bagasse, rice hulls, peanut shells, and cassava stalks was investigated. The prehydrolysis was performed at 122°C during 20, 40, or 60 min using 2% H2SO4 at a solid-to-liquid ratio of 1∶10. Sugar formation increased with increasing reaction time. Xylose, glucose, arabinose, and galactose were detected in all of the prehydrolysates, whereas mannose was found only in the prehydrolysates of peanut shells and cassava stalks. The hemicelluloses of bagasse were hydrolyzed to a high-extent yielding concentrations of xylose and arabinose of 19.1 and 2.2 g/L, respectively, and a xylan conversion of more than 80%. High-glucose concentrations (26-33.5 g/L) were found in the prehydrolysates of rice hulls, probably because of hydrolysis of starch of grain remains in the hulls. Peanut shells and cassava stalks rendered low amounts of sugars on prehydrolysis, indicating that the conditions were not severe enough to hydrolyze the hemicelluloses in these materials quantitatively. All prehydrolysates were readily fermentable by Saccharomyces cerevisiae. The dilute-acid prehydrolysis resulted in a 2.7-to 3.7-fold increase of the enzymatic convertibility of bagasse, but was not efficient for improving the enzymatic hydrolysis of peanut shells, cassava stalks, or rice hulls.

  15. Stainless steels with low contents in residual elements for nitric acid environments. Influence of melting processes

    International Nuclear Information System (INIS)

    Nitric acid solutions, as they are for instance employed in the chemical treatment of nuclear fuels, do not apparently pose any more corrosion problems and the safe use of the several steels is well documented. The most difficult corrosion problems are next those related to ''tunnel'' penetrations, in the hot-rolling direction (longitudinal). This phenomenon can be quite important such as to imperial complex structures. Up to the last few years, the only manner to eliminate such ''tunnel'' corrosions was to carry out special operations of remelting and refining under careful selected slag (Electro Slag Remelting or ESR). It turns out indeed that non metallic inclusions are the prime factors in this type of corrosion. Well adapted ladle refining processes made possible to obtain equivalent results at lower costs, while purity and cleanliness are improved to such a degree that a steel of type Cr 18 - Ni 10 thus produced exhibit a nearly absolute resistance to intergranular corrosion in the 14 N (65%) boiling nitric acid (the Huey test) whatever the ''sensitization'' treatment, between 10000C and 6000C. In view of its very high tolerance to varied thermal cycles and of the near complete disappearance of any ''tunnel'' corrosion, such a steel is of great interest when complex parts are produced, by machining forged or rolled metal, which is then assembled by welding techniques or procedures which would be forbidden in the case of usual Cr 18 -Ni 10 steels. Similar improvements are also obtained on the two other special steels used in nitric environments: Cr 25 - Ni 20 - C <= 0,020 (Nb) and Cr 17 - Ni 14 - Si 4 - C <= 0,015 (Nb)

  16. Leaching and selective copper recovery from acidic leachates of Três Marias zinc plant (MG, Brazil) metallurgical purification residues.

    Science.gov (United States)

    Sethurajan, Manivannan; Huguenot, David; Lens, Piet N L; Horn, Heinrich A; Figueiredo, Luiz H A; van Hullebusch, Eric D

    2016-07-15

    Zinc plant purification residue (ZPR), a typical Zn-hydrometallurgical waste, was collected from the Três Marias Zn plant (MG, Brazil). ZPR was characterized for its metal content and fractionation, mineralogy, toxicity and leachability. Toxicity characteristics leaching procedure (TCLP) and European Community Bureau of Reference (BCR) sequential extraction results revealed that this ZPR displays high percentages of metals (Cd, Cu, Zn and Pb) in the highly mobilizable fractions, increasing its hazardous potential. Bulk chemical analysis, pH dependent leaching and acid (H2SO4) leaching studies confirm that the ZPR is polymetallic, rich in Cd, Cu and Zn. The sulfuric acid concentration (1 M), agitation speed (450 rpm), temperature (40 °C) and pulp density (20 g L(-1)) were optimized to leach the maximum amount of heavy metals (Cd, Cu and Zn). Under optimum conditions, more than 50%, 70% and 60% of the total Cd, Cu and Zn present in the ZPR can be leached, respectively. The metals in the acid leachates were investigated for metal sulfide precipitation with an emphasis on selective Cu recovery. Metal sulfide precipitation process parameters such as initial pH and Cu to sulfide ratio were optimized as pH 1.5 and 1:0.5 (Cu:sulfide) mass ratio, respectively. Under optimum conditions, more than 95% of Cu can be selectively recovered from the polymetallic ZPR leachates. The Cu precipitates characterization studies reveal that they are approximately 0.1 μm in diameter and mainly consist of Cu and S. XRD analysis showed covellite (CuS), chalcanthite (CuSO4·5H2O) and natrochalcite (NaCu2(SO4)2(OH)·H2O) as the mineral phases. ZPRs can thus be considered as an alternative resource for copper production. PMID:27074201

  17. An arginine-aspartate network in the active site of bacterial TruB is critical for catalyzing pseudouridine formation.

    Science.gov (United States)

    Friedt, Jenna; Leavens, Fern M V; Mercier, Evan; Wieden, Hans-Joachim; Kothe, Ute

    2014-04-01

    Pseudouridine synthases introduce the most common RNA modification and likely use the same catalytic mechanism. Besides a catalytic aspartate residue, the contributions of other residues for catalysis of pseudouridine formation are poorly understood. Here, we have tested the role of a conserved basic residue in the active site for catalysis using the bacterial pseudouridine synthase TruB targeting U55 in tRNAs. Substitution of arginine 181 with lysine results in a 2500-fold reduction of TruB's catalytic rate without affecting tRNA binding. Furthermore, we analyzed the function of a second-shell aspartate residue (D90) that is conserved in all TruB enzymes and interacts with C56 of tRNA. Site-directed mutagenesis, biochemical and kinetic studies reveal that this residue is not critical for substrate binding but influences catalysis significantly as replacement of D90 with glutamate or asparagine reduces the catalytic rate 30- and 50-fold, respectively. In agreement with molecular dynamics simulations of TruB wild type and TruB D90N, we propose an electrostatic network composed of the catalytic aspartate (D48), R181 and D90 that is important for catalysis by fine-tuning the D48-R181 interaction. Conserved, negatively charged residues similar to D90 are found in a number of pseudouridine synthases, suggesting that this might be a general mechanism.

  18. Composition of the amino acid and amino sugar for molecular weight fractions of hot-water extractable soil organic matters from soils with plant residue compost or mineral fertilization

    Science.gov (United States)

    Moriizumi, M.; Matsunaga, T.; Uezono, I.; Kato, N.

    2009-04-01

    The hot-water extractable organic nitrogen is well known as a laboratory index of mineralizable nitrogen. This available nitrogen is indispensable for growth of plants because of being absorbed in crops. We measured the composition of the amino acid and amino sugar for molecular weight fractions in hot-water extractable organic matters to understand the source of the available nitrogen in soils inserted a compost. Two soil samples were collected from fields (Soil Type; Andosol) in National Agricultural Research Center in Tsukuba, Japan. A plant residue compost of 2 kga-1y-1 during 25 year has been applied to a soil and another soil was under the mineral fertilization. Organic matters were extracted from the soils of 3 g in the water of 50 ml at 80 degree centigrade for16 hours. The molecular size distribution of the hot-water extractable organic matters was analyzed by HPSCE (column YMC Diol-120, elution; 50mM phosphate buffer under pH=7.0, flow rate 1 mlmin-1), and 20 fractions were collected at regular intervals in the retention time. The chromatograms were monitored under the absorbance at 280 nm and fluorescence intensity at Ex.280 nm: Em.330nm. The concentrations of the 15 amino acids and three amino sugars (muramic acid, glucosamine, and galactosamine) for the molecule weight fractions were measured by HPLC as o-phthaldialdehyde (OPA) derivatives after the vapor HCl hydrolysis. Organic nitrogen concentrations of the hot-water extractable organic matters in the soil inserted the compost (C-soil) and the mineral fertilization soil (M-soil) were 133 and 35 mgkg-1, respectively. The extracted organic matters had the variable molecule weight (103- 104 Da). The concentrations of the amino acid and amino sugar of organic nitrogen in the C-soil were higher than those in the M-soil in all fractions. The fractions were classified into 3 groups (LW, MW, and SW) based on the molecule weight and spectroscopic characteristics. Each group had unique composition of the amino

  19. Evaluation of crop residues on potassium kinetics in an acid soil and potassium use efficiency in potato-garlic sequence using tracer 86Rb

    International Nuclear Information System (INIS)

    Greenhouse and laboratory studies were conducted on an acid soil in order to evaluate the role of two crop residues i.e. paddy and wheat along with farmyard manure on potassium kinetics and its availability in the potato-garlic sequence using tracer 86Rb. Under rapid equilibrium, application of crop residues of paddy, wheat straw and FYM were able to enhance soil pH and organic carbon content. In addition, their application helped in enhancing soil K availability indices like water soluble, available and non-exchangeable -K. This was further augmented by the Q/I studies using 86Rb where application of organic residues helped in lowering the potassium buffering capacity of the soil. Greenhouse study supplemented the results obtained from laboratory study where application of crop residues/FYM were able to improve the potato yield significantly and maintained higher concentration of K in potato leaf at early growth stages. A significant correlation was obtained between leaf K and haulms-K with that of 86Rb activities in potato leaf at 35 days and 86Rb absorbed in the haulms, respectively. Residues/ FYM and PK application to potato left sufficient residual effect on succeeding garlic crop. In potato-garlic sequence, K recovery was highest with FYM while N and P recoveries were higher with wheat residues. The nutrient recoveries with PK application followed law of diminishing returns. (author)

  20. A thermolabile aspartic proteinase from Mucor mucedo DSM 809: gene identification, cloning, and functional expression in Pichia pastoris.

    Science.gov (United States)

    Yegin, Sirma; Fernandez-Lahore, Marcelo

    2013-06-01

    In this study, the cDNA encoding the aspartic proteinase of Mucor mucedo DSM 809 has been identified by RNA ligased-mediated and oligo-capping rapid amplification of cDNA ends (RACE) technique. The gene contained an open reading frame of 1,200 bp and encoded for a signal peptide of 21 amino acid residues. Two N-glycosylation sites were observed within the identified sequence. The proteinase gene was cloned into the vector pGAPZαA and expressed in Pichia pastoris X-33 for the first time. The protein has been secreted in functionally active form into the culture medium. The expression system does not require any acid activation process. The factors affecting the expression level were optimized in shaking flask cultures. Maximum enzyme production was observed with an initial medium pH of 3.5 at 20 °C and 220 rpm shaking speed utilizing 4 % glucose as a carbon and energy source. The enzyme was purified with cation exchange chromatography and further studies revealed that the enzyme was secreted in glycosylated form. The purified enzyme exhibited remarkable sensitivity to thermal treatment and became completely inactivated after incubation at 55 °C for 10 min. These results indicated that the recombinant proteinase could be considered as a potential rennet candidate for the cheese-making industry.

  1. Determination of cyanuric acid residues in catfish, trout, tilapia, salmon and shrimp by liquid chromatography-tandem mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Karbiwnyk, Christine M. [Animal Drugs Research Center, U.S. Food and Drug Administration, P.O. Box 25087, Denver, CO 80225-0087 (United States)], E-mail: christine.karbiwnyk@fda.hhs.gov; Andersen, Wendy C.; Turnipseed, Sherri B. [Animal Drugs Research Center, U.S. Food and Drug Administration, P.O. Box 25087, Denver, CO 80225-0087 (United States); Storey, Joseph M.; Madson, Mark R. [Denver District Laboratory, U.S. Food and Drug Administration, P.O. Box 25087, Denver, CO 80225-0087 (United States); Miller, Keith E. [Center for Veterinary Medicine, U.S. Food and Drug Administration, 8401 Muirkirk Road, Laurel, MD 20708 (United States); Gieseker, Charles M.; Miller, Ron A.; Rummel, Nathan G.; Reimschuessel, Renate [University of Denver, Department of Chemistry and Biochemistry, Denver, CO 80208 (United States)

    2009-04-01

    In May 2007, investigators discovered that waste material from the pet food manufacturing process contaminated with melamine (MEL) and/or cyanuric acid (CYA) had been added to hog and chicken feeds. At this time, investigators also learned that adulterated wheat gluten had been used in the manufacture of aquaculture feeds. Concern that the contaminated feed had been used in aquaculture and could enter the human food supply prompted the development of a method for the determination of CYA residues in the edible tissues of fish and shrimp. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was employed as a sensitive technique for the analysis of CYA in catfish, tilapia, salmon, trout and shrimp tissue. CYA was extracted from ground fish or shrimp with an acetic acid solution, defatted with hexane, and isolated with a graphitic carbon black solid-phase extraction column. Residues were separated from matrix components using a porous graphitic carbon LC column, and then analyzed with electrospray ionization in negative ion mode on a triple quadrupole mass spectrometer. Selective reaction monitoring was performed on the [M-H]{sup -}m/z 128 ion resulting in the product ions m/z 85 and 42. Recoveries from catfish, tilapia and trout fortified with 10-100 {mu}g kg{sup -1} of CYA averaged 67% with a relative standard deviation (R.S.D.) of 18% (n = 107). The average method detection limit (MDL) for catfish, tilapia and trout is 3.5 {mu}g kg{sup -1}. An internal standard, {sup 13}C{sub 3}-labeled CYA, was used in the salmon and shrimp extractions. Average recovery of CYA from salmon was 91% (R.S.D. = 15%, n = 18) with an MDL of 7.4 {mu}g kg{sup -1}. Average recovery of CYA from shrimp was 85% (R.S.D. = 10%, n = 13) with an MDL of 3.5 {mu}g kg{sup -1}.

  2. Identification of amino acid residues essential to the activity of lyase CpcT1 from Nostoc sp. PCC7120.

    Science.gov (United States)

    Zhang, Juan; Sun, Ya Fang; Zhao, Kai Hong; Zhou, Ming

    2012-12-10

    The phycocyanin lyase CpcT1 (encoded by gene all5339) and lyase CpcS1 (encoded by gene alr0617) are capable of catalyzing the phycocyanobilin (PCB) covalently bound to the different sites of phycocyanin's and phycoerythrocyanin's β subunits, respectively. Lyase CpcS1, whose catalytic mechanism had been researched clearly, participates in the covalent coupling of phycobilin and apoprotein in the form of chaperone, and its important amino acids have been confirmed. In order to identify the functional amino acid residues of CpcT1, chemical modification was conducted to arginine, histidine, tryptophan, lysine and amino acid carboxyl of CpcT1. The results indicated that the catalytic activity of the CpcT1 was changed. After the modification of arginine, tryptophan and histidine, site-directed mutations were performed to those highly conserved amino acids which were selected by means of homologous comparison. The mutated lyase, apoprotein and the enzymes that synthesize the phycobilins were recombined in Escherichia coli (E. coli) and in vitro, yielding chromoproteins, which were detected by fluorescence and UV absorption spectrometry. The spectra were compared with that of the chromoprotein catalyzed by wild type lyase CpcT1, achieving relative specific activities of the various mutants. Meanwhile, the mutants were expressed in E. coli, and then circular dichroism structure of near-UV region was determined. The results demonstrated that H33F, W175S, R97A, C137S and C116S influence the catalytic activity of CpcT1. Being different from wild CpcT1, a great deal of α helix was involved in the structure of circular dichroism of R97A and W13S. CpcT1 or its mutants and the enzymes that synthesize the phycobilins, were reconstituted in E. coli and detected by spectra to check the bounding of lyases and PCB. The results of spectra and SDS-PAGE confirm that CpcT1 and its mutants cannot bind phycobilin, differing from the catalytic mechanism of CpcS1. PMID:22982227

  3. Separating nano graphene oxide from the residual strong-acid filtrate of the modified Hummers method with alkaline solution

    International Nuclear Information System (INIS)

    Graphical abstract: By adding an alkaline (NaOH or KOH) solution, the unprecipitated nano graphene oxide undergoes fast aggregation from the residual strong-acid filtrate of the modified Hummers method and forms the stable floccules when the pH value of the filtrate is about 1.7. The acid–base interaction with the surface functional groups of the carbon layers plays a role in the aggregation of the unprecipitated nano graphene oxide. - Highlights: • The novel and high-efficient method for separating graphene oxide was showed. • Graphene oxide undergoes aggregation and forms the floccules when pH value is ∼1.7. • The acid–base interaction plays a role in the aggregation of graphene oxide. - Abstract: In the modified Hummers method for preparing graphene oxide, the yellow slurry can be obtained. After filtering through a quantitative filter paper, the strong-acid filtrate containing the unprecipitated nano graphene oxide was gained. The corresponding filtrate was added gradually with an alkaline (NaOH or KOH) solution at room temperature. The unprecipitated nano graphene oxide could undergo fast aggregation when the pH value of the filtrate was about 1.7 and formed the stable floccules. X-ray diffraction analysis shows the dominant peak of the floccules is about 11°, which accords to the peak of graphene oxide. Spectra of X-ray photoelectron spectroscopy confirm the presence in the floccules of an abundance of oxygen functional groups and the purified graphene oxide floccules can be obtained. Atomic force microscopy measurement shows the graphene oxide floccules consists of sheet-like objects, mostly containing only a few layers (about 5 layers). Zeta potential analysis demonstrates the surface charge of the graphene oxide is pH-sensitive and its isoelectric point is ∼1.7. The flocculation mechanism of graphene oxide ascribes to the acid–base interaction with the surface functional groups of the carbon layers

  4. Residue-specific Incorporation of Noncanonical Amino Acids into Model Proteins Using an Escherichia coli Cell-free Transcription-translation System.

    Science.gov (United States)

    Worst, Emanuel G; Exner, Matthias P; De Simone, Alessandro; Schenkelberger, Marc; Noireaux, Vincent; Budisa, Nediljko; Ott, Albrecht

    2016-01-01

    The canonical set of amino acids leads to an exceptionally wide range of protein functionality. Nevertheless, the set of residues still imposes limitations on potential protein applications. The incorporation of noncanonical amino acids can enlarge this scope. There are two complementary approaches for the incorporation of noncanonical amino acids. For site-specific incorporation, in addition to the endogenous canonical translational machineries, an orthogonal aminoacyl-tRNA-synthetase-tRNA pair must be provided that does not interact with the canonical ones. Consequently, a codon that is not assigned to a canonical amino acid, usually a stop codon, is also required. This genetic code expansion enables the incorporation of a noncanonical amino acid at a single, given site within the protein. The here presented work describes residue-specific incorporation where the genetic code is reassigned within the endogenous translational system. The translation machinery accepts the noncanonical amino acid as a surrogate to incorporate it at canonically prescribed locations, i.e., all occurrences of a canonical amino acid in the protein are replaced by the noncanonical one. The incorporation of noncanonical amino acids can change the protein structure, causing considerably modified physical and chemical properties. Noncanonical amino acid analogs often act as cell growth inhibitors for expression hosts since they modify endogenous proteins, limiting in vivo protein production. In vivo incorporation of toxic noncanonical amino acids into proteins remains particularly challenging. Here, a cell-free approach for a complete replacement of L-arginine by the noncanonical amino acid L-canavanine is presented. It circumvents the inherent difficulties of in vivo expression. Additionally, a protocol to prepare target proteins for mass spectral analysis is included. It is shown that L-lysine can be replaced by L-hydroxy-lysine, albeit with lower efficiency. In principle, any

  5. Three amino acid residues bind corn odorants to McinOBP1 in the polyembryonic endoparasitoid of Macrocentrus cingulum Brischke.

    Directory of Open Access Journals (Sweden)

    Tofael Ahmed

    Full Text Available Odorant binding proteins (OBPs play a central role in transporting odorant molecules from the sensillum lymph to olfactory receptors to initiate behavioral responses. In this study, the OBP of Macrocentrus cingulum McinOBP1 was expressed in Escherichia coli and purified by Ni ion affinity chromatography. Real-time PCR experiments indicate that the McinOBP1 is expressed mainly in adult antennae, with expression levels differing by sex. Ligand-binding experiments using N-phenyl-naphthylamine (1-NPN as a fluorescent probe demonstrated that the McinOBP1 can bind green-leaf volatiles, including aldehydes and terpenoids, but also can bind aliphatic alcohols with good affinity, in the order trans-2-nonenal>cis-3-hexen-1-ol>trans-caryophelle, suggesting a role of McinOBP1 in general odorant chemoreception. We chose those three odorants for further homology modeling and ligand docking based on their binding affinity. The Val58, Leu62 and Glu130 are the key amino acids in the binding pockets that bind with these three odorants. The three mutants, Val58, Leu62 and Glu130, where the valine, leucine and glutamic residues were replaced by alanine, proline and alanine, respectively; showed reduced affinity to these odorants. This information suggests, Val58, Leu62 and Glu130 are involved in the binding of these compounds, possibly through the specific recognition of ligands that forms hydrogen bonds with the ligands functional groups.

  6. RESIDUAL COMPRESSIVE STRENGTH OF FLY ASH BASED GLASS FIBRE REINFORCED HIGH PERFORMANCE CONCRETE SUBJECTED TO ACID ATTACK

    Directory of Open Access Journals (Sweden)

    Dr.H.Sudarsana Rao

    2012-01-01

    Full Text Available In recent years, improvements in concrete properties have been achieved by the invention of High- Performance-Concrete (HPC. Improvements involving a combination of improved compaction, improved paste characteristics and aggregate-matrix bond, and reduced porosity are achieved through HPC. The ductility of HPC can be improved by altering its composition through the addition of glass fibers in the design mix. High- Performance-Concrete made with glass fibers inside is regarded as Glass Fiber Reinforced High Performance Concrete (GFRHPC. This paper presents the details of an experimental investigation planned to utilize fly ash in the production of Glass fibre reinforced High-Performance-Concrete (GFRHPC. The investigation examines the progressive deterioration of concrete mixtures containing various combinations of fly ash based GFRHPCmixes exposed to sulphate and chloride solutions. Acid attack tests have been conducted to measure the durability of GFRHPC. Cubes of 150X150X150 mm have been cast, cured and then kept immersed in 5%concentrated solutions of HCl, H2SO4 and MgSO4 for 30, 60 and 90 days and then tested to record the residual compressive strengths of GFRHPC produced with the fly ash mineral admixtures. The results have been analyzed and useful conclusions have been drawn.

  7. Antiretroviral intensification and valproic acid lack sustained effect on residual HIV-1 viremia or resting CD4+ cell infection.

    Directory of Open Access Journals (Sweden)

    Nancie M Archin

    Full Text Available BACKGROUND: Human immunodeficiency virus (HIV infection that persists despite antiretroviral therapy (ART is a daunting problem. Given the limited evidence that resting CD4+ T cell infection (RCI is affected by the histone deacetylase (HDAC inhibitor valproic acid (VPA, we measured the stability of RCI and residual viremia in patients who added VPA with or without raltegravir (RAL, or enfuvirtide (ENF with or without VPA, to standard ART. METHODS: Patients with plasma HIV RNA50% was seen in six volunteers after the addition of RAL and VPA. In 4 of the 6 patients this lack of effect might be attributed to intermittent viremia, low VPA levels, or intermittent study therapy adherence. Overall, there was no effect of the addition of RAL or ENF on low-level viremia measured by SCA. CONCLUSIONS: The prospective addition of VPA and RAL, VPA and ENF, or ENF failed to progressively reduce the frequency of RCI, or ablate intermittent and low-level viremia. New approaches such as more potent HDAC inhibition, alone or in combination with intensified ART or other agents that may disrupt proviral latency must be pursued.

  8. Residues that influence coenzyme preference in the aldehyde dehydrogenases.

    Science.gov (United States)

    González-Segura, Lilian; Riveros-Rosas, Héctor; Julián-Sánchez, Adriana; Muñoz-Clares, Rosario A

    2015-06-01

    To find out the residues that influence the coenzyme preference of aldehyde dehydrogenases (ALDHs), we reviewed, analyzed and correlated data from their known crystal structures and amino-acid sequences with their published kinetic parameters for NAD(P)(+). We found that the conformation of the Rossmann-fold loops participating in binding the adenosine ribose is very conserved among ALDHs, so that coenzyme specificity is mainly determined by the nature of the residue at position 195 (human ALDH2 numbering). Enzymes with glutamate or proline at 195 prefer NAD(+) because the side-chains of these residues electrostatically and/or sterically repel the 2'-phosphate group of NADP(+). But contrary to the conformational rigidity of proline, the conformational flexibility of glutamate may allow NADP(+)-binding in some enzymes by moving the carboxyl group away from the 2'-phosphate group, which is possible if a small neutral residue is located at position 224, and favored if the residue at position 53 interacts with Glu195 in a NADP(+)-compatible conformation. Of the residues found at position 195, only glutamate interacts with the NAD(+)-adenosine ribose; glutamine and histidine cannot since their side-chain points are opposite to the ribose, probably because the absence of the electrostatic attraction by the conserved nearby Lys192, or its electrostatic repulsion, respectively. The shorter side-chains of other residues-aspartate, serine, threonine, alanine, valine, leucine, or isoleucine-are distant from the ribose but leave room for binding the 2'-phosphate group. Generally, enzymes having a residue different from Glu bind NAD(+) with less affinity, but they can also bind NADP(+) even sometimes with higher affinity than NAD(+), as do enzymes containing Thr/Ser/Gln195. Coenzyme preference is a variable feature within many ALDH families, consistent with being mainly dependent on a single residue that apparently has no other structural or functional roles, and therefore can

  9. Model of the complex of Parathyroid hormone-2 receptor and Tuberoinfundibular peptide of 39 residues

    Directory of Open Access Journals (Sweden)

    Persson Bengt

    2010-10-01

    Full Text Available Abstract Background We aim to propose interactions between the parathyroid hormone-2 receptor (PTH2R and its ligand the tuberoinfundibular peptide of 39 residues (TIP39 by constructing a homology model of their complex. The two related peptides parathyroid hormone (PTH and parathyroid hormone related protein (PTHrP are compared with the complex to examine their interactions. Findings In the model, the hydrophobic N-terminus of TIP39 is buried in a hydrophobic part of the central cavity between helices 3 and 7. Comparison of the peptide sequences indicates that the main discriminator between the agonistic peptides TIP39 and PTH and the inactive PTHrP is a tryptophan-phenylalanine replacement. The model indicates that the smaller phenylalanine in PTHrP does not completely occupy the binding site of the larger tryptophan residue in the other peptides. As only TIP39 causes internalisation of the receptor and the primary difference being an aspartic acid in position 7 of TIP39 that interacts with histidine 396 in the receptor, versus isoleucine/histidine residues in the related hormones, this might be a trigger interaction for the events that cause internalisation. Conclusions A model is constructed for the complex and a trigger interaction for full agonistic activation between aspartic acid 7 of TIP39 and histidine 396 in the receptor is proposed.

  10. Determination of small halogenated carboxylic acid residues in drug substances by high performance liquid chromatography-diode array detection following derivatization with nitro-substituted phenylhydrazines.

    Science.gov (United States)

    Hou, Desheng; Fan, Jingjing; Han, Lingfei; Ruan, Xiaoling; Feng, Feng; Liu, Wenyuan; Zheng, Feng

    2016-03-18

    A method for the determination of small halogenated carboxylic acid (HCA) residues in drug substances is urgently needed because of the potential of HCAs for genotoxicity and carcinogenicity in humans. We have now developed a simple method, involving derivatization followed by high performance liquid chromatography-diode array detection (HPLC-DAD), for the determination of six likely residual HCAs (monochloroacetic acid, monobromoacetic acid, dichloroacetic acid, 2-chloropropionic acid, 2-bromopropionic acid and 3-chloropropionic acid) in drug substances. Different nitro-substituted phenylhydrazines (NPHs) derivatization reagents were systematically compared and evaluated. 2-Nitrophenylhydrazine hydrochloride (2-NPH·HCl) was selected as the most suitable choice since its derivatives absorb strongly at 392 nm, a region of the spectrum where most drug substances and impurities absorb very weakly. During the derivatization process, the commonly used catalyst, pyridine, caused rapid dechlorination or chlorine substitution of α-halogenated derivatives. To avoid these unwanted side reactions, a reliable derivatization method that did not use pyridine was developed. Reaction with 2-NPH·HCl using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride as coupling agent in acetonitrile-water (70:30) at room temperature for 2h gave complete reaction and avoided degradation products. The derivatives were analyzed, without any pretreatment, using gradient HPLC with detection in the near visible region. Organic acids commonly found in drug substances and other impurities did not interfere with the analysis. Good linearity (r>0.999) and low limits of quantitation (0.05-0.12 μg mL(-1)) were obtained. The mean recoveries were in the range of 80-115% with RSD <5.81% except for 3-CPA in ibuprofen which was 78.5%. The intra- and inter-day precisions were expressed as RSD <1.98% and <4.39%, respectively. Finally, the proposed method was successfully used for the residue

  11. Determination of small halogenated carboxylic acid residues in drug substances by high performance liquid chromatography-diode array detection following derivatization with nitro-substituted phenylhydrazines.

    Science.gov (United States)

    Hou, Desheng; Fan, Jingjing; Han, Lingfei; Ruan, Xiaoling; Feng, Feng; Liu, Wenyuan; Zheng, Feng

    2016-03-18

    A method for the determination of small halogenated carboxylic acid (HCA) residues in drug substances is urgently needed because of the potential of HCAs for genotoxicity and carcinogenicity in humans. We have now developed a simple method, involving derivatization followed by high performance liquid chromatography-diode array detection (HPLC-DAD), for the determination of six likely residual HCAs (monochloroacetic acid, monobromoacetic acid, dichloroacetic acid, 2-chloropropionic acid, 2-bromopropionic acid and 3-chloropropionic acid) in drug substances. Different nitro-substituted phenylhydrazines (NPHs) derivatization reagents were systematically compared and evaluated. 2-Nitrophenylhydrazine hydrochloride (2-NPH·HCl) was selected as the most suitable choice since its derivatives absorb strongly at 392 nm, a region of the spectrum where most drug substances and impurities absorb very weakly. During the derivatization process, the commonly used catalyst, pyridine, caused rapid dechlorination or chlorine substitution of α-halogenated derivatives. To avoid these unwanted side reactions, a reliable derivatization method that did not use pyridine was developed. Reaction with 2-NPH·HCl using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride as coupling agent in acetonitrile-water (70:30) at room temperature for 2h gave complete reaction and avoided degradation products. The derivatives were analyzed, without any pretreatment, using gradient HPLC with detection in the near visible region. Organic acids commonly found in drug substances and other impurities did not interfere with the analysis. Good linearity (r>0.999) and low limits of quantitation (0.05-0.12 μg mL(-1)) were obtained. The mean recoveries were in the range of 80-115% with RSD <5.81% except for 3-CPA in ibuprofen which was 78.5%. The intra- and inter-day precisions were expressed as RSD <1.98% and <4.39%, respectively. Finally, the proposed method was successfully used for the residue

  12. Crystal Structures of the Histo-Aspartic Protease (HAP) from Plasmodium falciparum

    Energy Technology Data Exchange (ETDEWEB)

    Bhaumik, Prasenjit; Xiao, Huogen; Parr, Charity L.; Kiso, Yoshiaki; Gustchina, Alla; Yada, Rickey Y.; Wlodawer, Alexander; (Guelph); (Kyoto); (NCI)

    2009-08-07

    The structures of recombinant histo-aspartic protease (HAP) from malaria-causing parasite Plasmodium falciparum as apoenzyme and in complex with two inhibitors, pepstatin A and KNI-10006, were solved at 2.5-, 3.3-, and 3.05-{angstrom} resolutions, respectively. In the apoenzyme crystals, HAP forms a tight dimer not seen previously in any aspartic protease. The interactions between the monomers affect the conformation of two flexible loops, the functionally important 'flap' (residues 70-83) and its structural equivalent in the C-terminal domain (residues 238-245), as well as the orientation of helix 225-235. The flap is found in an open conformation in the apoenzyme. Unexpectedly, the active site of the apoenzyme contains a zinc ion tightly bound to His32 and Asp215 from one monomer and to Glu278A from the other monomer, with the coordination of Zn resembling that seen in metalloproteases. The flap is closed in the structure of the pepstatin A complex, whereas it is open in the complex with KNI-10006. Although the binding mode of pepstatin A is significantly different from that in other pepsin-like aspartic proteases, its location in the active site makes unlikely the previously proposed hypothesis that HAP is a serine protease. The binding mode of KNI-10006 is unusual compared with the binding of other inhibitors from the KNI series to aspartic proteases. The novel features of the HAP active site could facilitate design of specific inhibitors used in the development of antimalarial drugs.

  13. Reclamation of acidic mine residues by creation of technosoils with the addition of biochar and marble waste

    Science.gov (United States)

    Moreno-Barriga, Fabián; Díaz, Vicente; Acosta, José; Faz, Ángel; Zornoza, Raul

    2016-04-01

    This study reports the short-term effect of biochar and marble waste addition for the reclamation of acidic mine residues. A lab incubation was carried out for 90 days. Biochars derived from pig manure (PM), crop residues (CR) and municipal solid waste (MSW) were added to the soil at a rate of 20 g kg-1. The marble waste (MW) was added at a rate of 200 g kg-1. Bochars and MW were applied independently and combined. A control soil was used without application of amendments. The evolution of different physical, chemical and biochemical properties and availability of heavy metals was periodically monitored. Results showed that original pH (2.8) was increased with all amendments, those samples containing MW being the ones with the highest pH (~8.0). The electrical conductivity (EC) decreased from 6.6 to 3.0-4.5 mS cm-1 in all the treatments receiving MW. Soil organic C (SOC) increased in all samples receiving biochar up to 18-20 g kg-1, with no shifts during the 90 d incubation, indicating the high stability of the C supplied. Recalcitrant organic C accounted for ~90-98% of the SOC. No significant effect of amendment addition was observed for carbohydrates, soluble C, microbial biomass C and β-glucosidase activity. However, arylesterase activity increased with amendments, highly related to pH. The availability of heavy metals decreased up to 90-95% owing to the addition of amendments, mainly in samples containing MW. The MW provided conditions to increase pH and decrease EC and metals mobility. Biochar was an effective strategy to increase SOC, recalcitrant C and AS, essential to create soil structure. However, a labile source of organic matter should be added together with the proposed amendments to promote the activation of microbial communities. Acknowledgement : This work has been funded by Fundación Séneca (Agency of Science and Technology of the Region of Murcia, Spain) by the project 18920/JLI/13

  14. AspC-mediated aspartate metabolism coordinates the Escherichia coli cell cycle.

    Directory of Open Access Journals (Sweden)

    Feng Liu

    Full Text Available The fast-growing bacterial cell cycle consists of at least two independent cycles of chromosome replication and cell division. To ensure proper cell cycles and viability, chromosome replication and cell division must be coordinated. It has been suggested that metabolism could affect the Escherichia coli cell cycle, but the idea is still lacking solid evidences.We found that absence of AspC, an aminotransferase that catalyzes synthesis of aspartate, led to generation of small cells with less origins and slow growth. In contrast, excess AspC was found to exert the opposite effect. Further analysis showed that AspC-mediated aspartate metabolism had a specific effect in the cell cycle, as only extra aspartate of the 20 amino acids triggered production of bigger cells with more origins per cell and faster growth. The amount of DnaA protein per cell was found to be changed in response to the availability of AspC. Depletion of (pppGpp by ΔrelAΔspoT led to a slight delay in initiation of replication, but did not change the replication pattern found in the ΔaspC mutant.The results suggest that AspC-mediated metabolism of aspartate coordinates the E. coli cell cycle through altering the amount of the initiator protein DnaA per cell and the division signal UDP-glucose. Furthermore, AspC sequence conservation suggests similar functions in other organisms.

  15. An amino acid residue in the second extracellular loop determines the agonist-dependent tolerance property of the human D3 dopamine receptor.

    Science.gov (United States)

    Gil-Mast, Sara; Kortagere, Sandhya; Kota, Kokila; Kuzhikandathil, Eldo V

    2013-06-19

    The D3 dopamine receptor is a therapeutic target for treating various nervous system disorders such as schizophrenia, Parkinson's disease, depression, and addictive behaviors. The crystal structure of the D3 receptor bound to an antagonist was recently described; however, the structural features that contribute to agonist-induced conformational changes and signaling properties are not well understood. We have previously described the conformation-dependent tolerance and slow response termination (SRT) signaling properties of the D3 receptor and identified the C147 residue in the second intracellular loop (IL2) of the D3 receptor as important for the tolerance property. Interestingly, while IL2 and the C147 residue, in particular, were important for dopamine- and quinpirole-induced tolerance, this residue did not affect the severe tolerance induced by the high affinity, D3 receptor-selective agonist, PD128907. Here, we used D2/D3 receptor chimeras and site-specific D3 receptor mutants to identify another residue, D187, in the second extracellular loop (EC2) of the human D3 receptor that mediates the tolerance property induced by PD128907, quinpirole, pramipexole, and dopamine. Molecular dynamics simulations confirmed the distinct conformation adopted by D3 receptor during tolerance and suggested that in the tolerant D3 receptor the D187 residue in EC2 forms a salt bridge with the H354 residue in EC3. Indeed, site-directed mutation of the H354 residue resulted in loss of PD1287907-induced tolerance. The mapping of specific amino acid residues that contribute to agonist-dependent conformation changes and D3 receptor signaling properties refines the agonist-bound D3 receptor pharmacophore model which will help develop novel D3 receptor agonists. PMID:23477444

  16. Effect of the inclusion of fish residue oils in diets on the fatty acid profile of muscles of males and females lambari (Astyanax altiparanae

    Directory of Open Access Journals (Sweden)

    Ligia Uribe Gonçalves

    2012-09-01

    Full Text Available This study evaluated the effects of two lipids sources of fish residue (tilapia and salmon compared with a vegetable oil source (soybean oil on the fatty acid profiles of male and female lambari. This experiment was developed in a completely randomized experimental design in a 3 × 2 factorial arrangement, totaling 6 treatments resulting from the combination of the three experimental diets for both sexes, with four replications for each treatment. This study involved 120 male (2.58±0.13 g and 72 female lambari (4.00±0.09 g, fed the experimental diets twice a day until apparent satiation for a period of 60 days. Oleic, linoleic, palmitic and stearic fatty acids were found at higher concentrations in all experimental oils and diets, as well in the muscle of male and female lambari. The low amounts of arachidonic, eicosapentaenoic and docosahexaenoic acids in the experimental diets and subsequent greater concentrations in muscle tissue, suggested that lambari are able to desaturate and elongate the chain of fatty acids with 18 carbons. The fish of both sexes that received the diet with soybean oil showed high levels of n-6 fatty acids, especially of C18: 2n-6 and low levels of eicosapentaenoic and docosahexaenoic acids. The diet with salmon residue oil promoted higher levels of fatty acids of the n-3 series and resulted in the best n-3/n-6 ratio in the muscle of male and female lambari. The oils from fish residues can be a substitute for traditional fish oil and its use in the lambari diets does not impair its growth.

  17. Cauliflower mosaic virus produces an aspartic proteinase to cleave its polyproteins.

    OpenAIRE

    Torruella, M; Gordon, K; Hohn, T

    1989-01-01

    Cauliflower mosaic virus (CaMV), a plant pararetrovirus, produces polyproteins from its adjacent genes for the coat protein (ORF IV) and for enzymatic functions (ORF V). The N-terminal domain of the latter gene includes a sequence showing homology to the active site of other retroviral and acid proteases. We have now shown that this domain does indeed produce a functional aspartic protease that can process both the polyproteins. Mutations in the putative active site abolished virus infectivit...

  18. Amino acid residues 56 to 69 of HLA-A2 specify an antigenic determinant shared by HLA-A2 and HLA-B17.

    Science.gov (United States)

    Ways, J P; Rothbard, J B; Parham, P

    1986-07-01

    The mouse monoclonal antibody MA2.1 was previously used to define an epitope shared by native HLA-A2 and HLA-B17 molecules and amino acid sequence comparison of nine HLA-A,B,C molecules identified residues 62 to 65 as the region most likely to form this epitope. An unabsorbed rabbit antiserum raised against a peptide corresponding to residues 56 to 69 of HLA-A2 gives highly specific reactions with HLA-A2 and HLA-B17 heavy chains in Western blots. No interactions with native HLA-A2 and B17 molecules were detected in a variety of assays. Although the topographic relationship between the epitopes recognized by the rabbit antiserum and the monoclonal antibody could not be determined, the results show that residues 56 to 69 of HLA-A2 can form epitopes with specificity for HLA-A2 and HLA-B17.

  19. Medial temporal N-acetyl-aspartate in pediatric major depression.

    Science.gov (United States)

    MacMaster, Frank P; Moore, Gregory J; Russell, Aileen; Mirza, Yousha; Taormina, S Preeya; Buhagiar, Christian; Rosenberg, David R

    2008-10-30

    The medial temporal cortex (MTC) has been implicated in the pathogenesis of pediatric major depressive disorder (MDD). Eleven MDD case-control pairs underwent proton magnetic resonance spectroscopic imaging. N-acetyl-aspartate was lower in the left MTC (27%) in MDD patients versus controls. Lower N-acetyl-aspartate concentrations in MDD patients may reflect reduced neuronal viability. PMID:18703320

  20. Medial temporal N-acetyl aspartate in pediatric major depression

    Science.gov (United States)

    MacMaster, Frank P.; Moore, Gregory J; Russell, Aileen; Mirza, Yousha; Taormina, S. Preeya; Buhagiar, Christian; Rosenberg, David R.

    2008-01-01

    The medial temporal cortex (MTC) has been implicated in the pathogenesis of pediatric major depressive disorder (MDD). Eleven MDD-case control pairs underwent proton magnetic resonance spectroscopic imaging. N-acetyl-aspartate was lower in left MTC (27%) in MDD patients versus controls. Lower N-acetyl-aspartate concentrations in MDD patients may reflect reduced neuronal viability. PMID:18703320

  1. Effect of lactic acid bacteria inoculant and beet pulp addition on fermentation characteristics and in vitro ruminal digestion of vegetable residue silage.

    Science.gov (United States)

    Cao, Y; Cai, Y; Takahashi, T; Yoshida, N; Tohno, M; Uegaki, R; Nonaka, K; Terada, F

    2011-08-01

    The objective of this study was to determine the effect of beet pulp (BP) and lactic acid bacteria (LAB) on silage fermentation quality and in vitro ruminal dry matter (DM) digestion of vegetable residues, including white cabbage, Chinese cabbage, red cabbage, and lettuce. Silage was prepared using a small-scale fermentation system, and treatments were designed as control silage without additive or with BP (30% fresh matter basis), LAB inoculant Chikuso-1 (Lactobacillus plantarum, 5mg/kg, fresh matter basis), and BP+LAB. In vitro incubation was performed using rumen fluid mixed with McDougall's artificial saliva (at a ratio of 1:4, vol/vol) at 39°C for 6h to determine the ruminal fermentability of the vegetable residue silages. These vegetable residues contained high levels of crude protein (20.6-22.8% of DM) and moderate levels of neutral detergent fiber (22.7-33.6% of DM). In all silages, the pH sharply decreased and lactic acid increased, and the growth of bacilli, coliform bacteria, molds, and yeasts was inhibited by the low pH at the early stage of ensiling. The silage treated with BP or LAB had a lower pH and a higher lactic acid content than the control silage. After 6h of incubation, all silages had relatively high DM digestibility (38.6-44.9%); in particular, the LAB-inoculated silage had the highest DM digestibility and the lowest methane production. The vegetable residues had high nutritional content and high in vitro DM digestibility. Also, both the addition of a LAB inoculant and moisture adjustment with BP improved the fermentation quality of the vegetable residue silages. In addition, LAB increased DM digestibility and decreased ruminal methane production. PMID:21787927

  2. Differential isotope-labeling for Leu and Val residues in a protein by E. coli cellular expression using stereo-specifically methyl labeled amino acids

    Energy Technology Data Exchange (ETDEWEB)

    Miyanoiri, Yohei; Takeda, Mitsuhiro [Nagoya University, Structural Biology Research Center, Graduate School of Science (Japan); Okuma, Kosuke; Ono, Akira M.; Terauchi, Tsutomu [Tokyo Metropolitan University, Center for Priority Areas (Japan); Kainosho, Masatsune, E-mail: kainosho@tmu.ac.jp [Nagoya University, Structural Biology Research Center, Graduate School of Science (Japan)

    2013-09-21

    The {sup 1}H–{sup 13}C HMQC signals of the {sup 13}CH{sub 3} moieties of Ile, Leu, and Val residues, in an otherwise deuterated background, exhibit narrow line-widths, and thus are useful for investigating the structures and dynamics of larger proteins. This approach, named methyl TROSY, is economical as compared to laborious methods using chemically synthesized site- and stereo-specifically isotope-labeled amino acids, such as stereo-array isotope labeling amino acids, since moderately priced, commercially available isotope-labeled α-keto acid precursors can be used to prepare the necessary protein samples. The Ile δ{sub 1}-methyls can be selectively labeled, using isotope-labeled α-ketobutyrates as precursors. However, it is still difficult to prepare a residue-selectively Leu and Val labeled protein, since these residues share a common biosynthetic intermediate, α-ketoisovalerate. Another hindering drawback in using the α-ketoisovalerate precursor is the lack of stereo-selectivity for Leu and Val methyls. Here we present a differential labeling method for Leu and Val residues, using four kinds of stereo-specifically {sup 13}CH{sub 3}-labeled [U–{sup 2}H;{sup 15}N]-leucine and -valine, which can be efficiently incorporated into a protein using Escherichia coli cellular expression. The method allows the differential labeling of Leu and Val residues with any combination of stereo-specifically isotope-labeled prochiral methyls. Since relatively small amounts of labeled leucine and valine are required to prepare the NMR samples; i.e., 2 and 10 mg/100 mL of culture for leucine and valine, respectively, with sufficient isotope incorporation efficiency, this approach will be a good alternative to the precursor methods. The feasibility of the method is demonstrated for 82 kDa malate synthase G.

  3. Extracellular acid block and acid-enhanced inactivation of the Ca2+-activated cation channel TRPM5 involve residues in the S3-S4 and S5-S6 extracellular domains.

    Science.gov (United States)

    Liu, Dan; Zhang, Zheng; Liman, Emily R

    2005-05-27

    TRPM5, a member of the superfamily of transient receptor potential ion channels, is essential for the detection of bitter, sweet, and amino acid tastes. In heterologous cell types it forms a nonselective cation channel that is activated by intracellular Ca(2+). TRPM5 is likely to be part of the taste transduction cascade, and regulators of TRPM5 are likely to affect taste sensation. In this report we show that TRPM5, but not the related channel TRPM4b, is potently blocked by extracellular acidification. External acidification has two effects, a fast reversible block of the current (IC(50) pH = 6.2) and a slower irreversible enhancement of current inactivation. Mutation of a single Glu residue in the S3-S4 linker and a His residue in the pore region each reduced sensitivity of TRPM5 currents to fast acid block (IC(50) pH = 5.8 for both), and the double mutant was nearly insensitive to acidic pH (IC(50) pH = 5.0). Prolonged exposure to acidic pH enhanced inactivation of TRPM5 currents, and mutant channels that were less sensitive to acid block were also less sensitive to acid-enhanced inactivation, suggesting an intimate association between the two processes. These processes are, however, distinct because the pore mutant H896N, which has normal sensitivity to acid block, shows significant recovery from acid-enhanced inactivation. These data show that extracellular acidification acts through specific residues on TRPM5 to block conduction through two distinct but related mechanisms and suggest a possible interaction between extracellular pH and activation and adaptation of bitter, sweet, and amino acid taste transduction.

  4. Simultaneous screening analysis of 3-methyl-quinoxaline-2-carboxylic acid and quinoxaline-2-carboxylic acid residues in edible animal tissues by a competitive indirect immunoassay

    Science.gov (United States)

    Immunoassays contribute greatly to veterinary drug residue analysis and food safety, but there are no reported immunoassays on simultaneously detecting MQCA and QCA, the marker residues for carbadox and olaquindox. It is extremely difficult to produce broad-specificity antibodies that bind both res...

  5. Evaluation of ozonation technique for pesticide residue removal and its effect on ascorbic acid, cyanidin-3-glucoside, and polyphenols in apple (Malus domesticus) fruits.

    Science.gov (United States)

    Swami, Saurabh; Muzammil, Raunaq; Saha, Supradip; Shabeer, Ahammed; Oulkar, Dasharath; Banerjee, Kaushik; Singh, Shashi Bala

    2016-05-01

    Ozonated water dip technique was evaluated for the detoxification of six pesticides, i.e., chlorpyrifos, cypermethrin, azoxystrobin, hexaconazole, methyl parathion, and chlorothalonil from apple fruits. Results revealed that ozonation was better than washing alone. Ozonation for 15 min decreased residues of the test pesticides in the range of from 26.91 to 73.58%, while ozonation for 30 min could remove the pesticide residues by 39.39-95.14 % compared to 19.05-72.80 % by washing. Cypermethrin was the least removed pesticide by washing as well as by ozonation. Chlorothalonil, chlorpyrifos, and azoxystrobin were removed up to 71.45-95.14 % in a 30-min ozonation period. In case of methyl parathion removal, no extra advantage could be obtained by ozonation. The HPLC analysis indicated that ozonation also affected adversely the ascorbic acid and cyanidin-3-glucoside content of apples. However, 11 polyphenols studied showed a mixed trend. Gallic acid, 3,4-dihydroxybenzoic acid, catechin, epicatechin, p-coumaric acid, quercetin-3-O-glucoside, quercetin, and kaempferol were found to decrease while syringic acid, rutin, and resveratrol were found to increase in 30-min ozonation.

  6. Functional analysis of three amino acid residues of purR re-pressor, Trp147, Gln-218 and Gln-292 in Salmonella typhi-murium

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The amber mutation sites of 6 purR(am) mutants were determined bycloning and DNA sequencing. The results showed that the mutations were distributed at three different sites in PurR coding region, G721(→A), C933(→T) and C1155(→T), which respectively turn Trp-147,Gln-218 and Gln-292 of PurR into TAG terminal codon. To determine the effect of the three amino acid residues on regulatory function of PurR protein 5 different kinds of tRNA suppressor genes, Su3, Su4, Su6, Su7 and Su9 were used for creating the PurR protein variants with single amino acid substitution. The results indicated that Cys, Glu, Gly, His and Arg which substituted Trp-147 respectively all could not recover the regulation function of PurR. It confirmed that Trp-147 is a critical amino acid for the PurR function. Gln-292 substituted respectively by the same amino acids also could not recover the PurR function, demonstrating that Gln-292 is also an important amino acid residue in PurR.

  7. Intersubunit communication in the dihydroorotase-aspartate transcarbamoylase complex of Aquifex aeolicus.

    Science.gov (United States)

    Evans, Hedeel Guy; Fernando, Roshini; Vaishnav, Asmita; Kotichukkala, Mahalakshmi; Heyl, Deborah; Hachem, Fatme; Brunzelle, Joseph S; Edwards, Brian F P; Evans, David R

    2014-01-01

    Aspartate transcarbamoylase and dihydroorotase, enzymes that catalyze the second and third step in de novo pyrimidine biosynthesis, are associated in dodecameric complexes in Aquifex aeolicus and many other organisms. The architecture of the dodecamer is ideally suited to channel the intermediate, carbamoyl aspartate from its site of synthesis on the ATC subunit to the active site of DHO, which catalyzes the next step in the pathway, because both reactions occur within a large, internal solvent-filled cavity. Channeling usually requires that the reactions of the enzymes are coordinated so that the rate of synthesis of the intermediate matches its rate of utilization. The linkage between the ATC and DHO subunits was demonstrated by showing that the binding of the bisubstrate analog, N-phosphonacetyl-L-aspartate to the ATC subunit inhibits the activity of the distal DHO subunit. Structural studies identified a DHO loop, loop A, interdigitating between the ATC domains that would be expected to interfere with domain closure essential for ATC catalysis. Mutation of the DHO residues in loop A that penetrate deeply between the two ATC domains inhibits the ATC activity by interfering with the normal reciprocal linkage between the two enzymes. Moreover, a synthetic peptide that mimics that part of the DHO loop that binds between the two ATC domains was found to be an allosteric or noncompletive ATC inhibitor (K(i) = 22 μM). A model is proposed suggesting that loop A is an important component of the functional linkage between the enzymes. PMID:24353170

  8. Arginine of retinoic acid receptor beta which coordinates with the carboxyl group of retinoic acid functions independent of the amino acid residues responsible for retinoic acid receptor subtype ligand specificity.

    Science.gov (United States)

    Zhang, Zeng Ping; Hutcheson, Juliet M; Poynton, Helen C; Gabriel, Jerome L; Soprano, Kenneth J; Soprano, Dianne Robert

    2003-01-15

    The biological actions of retinoic acid (RA) are mediated by retinoic acid receptors (RARalpha, RARbeta, and RARgamma) and retinoid X receptors (RXRalpha, RXRbeta, and RXRgamma). Consistent with the X-ray crystal structures of RARalpha and RARgamma, site-directed mutagenesis studies have demonstrated the importance of a conserved Arg residue (alphaArg(276), betaArg(269), and gammaArg(278)) for coordination with the carboxyl group of RA. However, mutation of Arg(269) to Ala in RARbeta causes only a 3- to 6-fold increase in the K(d) for RA and EC(50) in RA-dependent transcriptional transactivation assays while the homologous mutation in either RARalpha or RARgamma causes a 110-fold and a 45-fold increase in EC(50) value, respectively. To further investigate the nature of this difference, we prepared mutant RARs to determine the effect of conversion of betaR269A to a mutant which mimics either RARalpha ligand selectivity (betaA225S/R269A) or RARgamma ligand selectivity (betaI263M/R269A/V338A). Our results demonstrate that in RARbeta mutants that acquire either RARalpha or RARgamma ligand specificity the Arg(269) position responsible for coordination with the carboxyl group of retinoids continued to function like that of RARbeta. Furthermore, three mutant receptors (betaA225S/R269A, betaA225S/F279, and alphaF286A) were found to have a greater than wild-type affinity for the RARalpha-selective ligand Am580. Finally, a homology-based computer model of the ligand binding domain (LBD) of RARbeta and the X-ray crystal structures of the LBD of both RARalpha and RARgamma are used to describe potential mechanisms responsible for the increased affinity of some mutants for Am580 and for the difference in the effect of mutation of Arg(269) in RARbeta compared to its homologous Arg in RARalpha and RARgamma.

  9. Sequence and structural features of binding site residues in protein-protein complexes: comparison with protein-nucleic acid complexes

    OpenAIRE

    Selvaraj S; Jayaram B; Saranya N; Gromiha M; Fukui Kazuhiko

    2011-01-01

    Abstract Background Protein-protein interactions are important for several cellular processes. Understanding the mechanism of protein-protein recognition and predicting the binding sites in protein-protein complexes are long standing goals in molecular and computational biology. Methods We have developed an energy based approach for identifying the binding site residues in protein–protein complexes. The binding site residues have been analyzed with sequence and structure based parameters such...

  10. 苯甲酸釜残液全部回收的工艺开发利用%Development on the Technique of Total Recovery of Benzoic Acid Residue

    Institute of Scientific and Technical Information of China (English)

    徐姣; 何杰; 张卫江; 杨焘; 焦书军; 胡雪东

    2009-01-01

    Benzoic acid residue is solid waste produced from the production of benzoic acid by oxidizing toluene. Because it contained important chemical raw materials such as benzoic acid, benzyl benzoate and fluorenone, it is necessary to recover them from the residue. In this work the technique featured with high efficiency evaporation and vacuum distillation was developed to obtain total recovery and utilization of the benzoic acid residue. By con-trolling the operation temperature at 260℃ and the pressure of 16 kPa in the rising and falling film evaporators, heavy components separated efficiently from the residue can be polymerized and the light components consisting of 63% of the residue entered into a benzoic acid vacuum distillation column. Keeping the temperature of polymeriza-tion at (280±10)℃, coumarone resin was produccd after adjusting the softening point according to the market re-quirements. Vacuum distillation was operated under the following conditions: top temperature at 186℃, top pres-sure of 16 kPa, bottom temperature at 240 250℃, reflux ratio being 3:1. Benzoic acid of 98% purity was distilled out from the column as a side stream and the bottom product was crude benzyl benzoate. By the developed tech-nique, the benzoic acid residue was splitted into three products, benzoic acid, crude benzyl benzoate and coumarone resin without any surplus waste.

  11. Magnitude of malate-aspartate reduced nicotinamide adenine dinucleotide shuttle activity in intact respiring tumor cells.

    Science.gov (United States)

    Greenhouse, W V; Lehninger, A L

    1977-11-01

    Measurements of respiration, CO2 and lactate production, and changes in the levels of various key metabolites of the glycolytic sequence and tricarboxylic acid cycle were made on five lines of rodent ascites tumor cells (two strains of Ehrlich ascites tumor cells, Krebs II carcinoma, AS-30D carcinoma, and L1210 cells) incubated aerobically in the presence of uniformly labeled D-[14C]glucose. From these data, as well as earlier evidence demonstrating that the reduced nicotinamide adenine dinucleotide (NADH) shuttle in these cells requires a transaminase step and is thus identified as the malate-aspartate shuttle (W.V.V. Greenhouse and A.L. Lehninger, Cancer Res., 36: 1392-1396, 1976), metabolic flux diagrams were constructed for the five cell lines. These diagrams show the relative rates of glycolysis, the tricarboxylic acid cycle, electron transport, and the malate-aspartate shuttle in these tumors. Large amounts of cytosolic NADH were oxidized by the mitochondrial respiratory chain via the NADH shuttle, comprising anywhere from about 20 to 80% of the total flow of reducing equivalents to oxygen in these tumors. Calculations of the sources of energy for adenosine triphosphate synthesis indicated that on the average about one-third of the respiratory adenosine triphosphate is generated by electron flow originating from cytosolic NADH via the malate-aspartate shuttle.

  12. Magnitude of malate-aspartate reduced nicotinamide adenine dinucleotide shuttle activity in intact respiring tumor cells.

    Science.gov (United States)

    Greenhouse, W V; Lehninger, A L

    1977-11-01

    Measurements of respiration, CO2 and lactate production, and changes in the levels of various key metabolites of the glycolytic sequence and tricarboxylic acid cycle were made on five lines of rodent ascites tumor cells (two strains of Ehrlich ascites tumor cells, Krebs II carcinoma, AS-30D carcinoma, and L1210 cells) incubated aerobically in the presence of uniformly labeled D-[14C]glucose. From these data, as well as earlier evidence demonstrating that the reduced nicotinamide adenine dinucleotide (NADH) shuttle in these cells requires a transaminase step and is thus identified as the malate-aspartate shuttle (W.V.V. Greenhouse and A.L. Lehninger, Cancer Res., 36: 1392-1396, 1976), metabolic flux diagrams were constructed for the five cell lines. These diagrams show the relative rates of glycolysis, the tricarboxylic acid cycle, electron transport, and the malate-aspartate shuttle in these tumors. Large amounts of cytosolic NADH were oxidized by the mitochondrial respiratory chain via the NADH shuttle, comprising anywhere from about 20 to 80% of the total flow of reducing equivalents to oxygen in these tumors. Calculations of the sources of energy for adenosine triphosphate synthesis indicated that on the average about one-third of the respiratory adenosine triphosphate is generated by electron flow originating from cytosolic NADH via the malate-aspartate shuttle. PMID:198130

  13. N-Methyl-D-Aspartate Receptor Signaling and Function in Cardiovascular Tissues.

    Science.gov (United States)

    McGee, Marie A; Abdel-Rahman, Abdel A

    2016-08-01

    Excellent reviews on central N-methyl-D-aspartate receptor (NMDAR) signaling and function in cardiovascular regulating neuronal pools have been reported. However, much less attention has been given to NMDAR function in peripheral tissues, particularly the heart and vasculature, although a very recent review discusses such function in the kidney. In this short review, we discuss the NMDAR expression and complexity of its function in cardiovascular tissues. In conscious (contrary to anesthetized) rats, activation of the peripheral NMDAR triggers cardiovascular oxidative stress through the PI3K-ERK1/2-NO signaling pathway, which ultimately leads to elevation in blood pressure. Evidence also implicates Ca release, in the peripheral NMDAR-mediated pressor response. Despite evidence of circulating potent ligands (eg, D-aspartate and L-aspartate, L-homocysteic acid, and quinolinic acid) and also their coagonist (eg, glycine or D-serine), the physiological role of peripheral cardiovascular NMDAR remains elusive. Nonetheless, the cardiovascular relevance of the peripheral NMDAR might become apparent when its signaling is altered by drugs, such as alcohol, which interact with the NMDAR or its downstream signaling mechanisms. PMID:27046337

  14. [Effect of mutations and modifications of amino acid residues on zinc-induced interaction of the metal-binding domain of β-amyloid with DNA].

    Science.gov (United States)

    Khmeleva, S A; Mezentsev, Y V; Kozin, S A; Mitkevich, V A; Medvedev, A E; Ivanov, A S; Bodoev, N V; Makarov, A A; Radko, S P

    2015-01-01

    Interaction of intranuclear β-amyloid with DNA is considered to be a plausible mechanism of Alzheimer's disease pathogenesis. The interaction of single- and double-stranded DNA with synthetic peptides was analyzed using surface plasmon resonance. The peptides represent the metal-binding domain of β-amyloid (amino acids 1-16) and its variants with chemical modifications and point substitutions of amino acid residues which are associated with enhanced neurotoxicity of β-amyloid in cell tests. It has been shown that the presence of zinc ions is necessary for the interaction of the peptides with DNA in solution. H6R substitution has remarkably reduced the ability of domain 1-16 to bind DNA. This is in accordance with the supposition that the coordination of a zinc ion by amino acid residues His6, Glu11, His13, and His14 of the β-amyloid metal-binding domain results in the occurrence of an anion-binding site responsible for the interaction of the domain with DNA. Zinc-induced dimerization and oligomerization of domain 1-16 associated with phosphorylation of Ser8 and the presence of unblocked amino- and carboxy-terminal groups have resulted in a decrease of peptide concentrations required for detection of the peptide-DNA interaction. The presence of multiple anion-binding sites on the dimers and oligomers is responsible for the enhancement of the peptide-DNA interaction. A substitution of the negatively charged residue Asp7 for the neutral residue Asn in close proximity to the anion-binding site of the domain 1-16 of Aβ facilitates the electrostatic interaction between this site and phosphates of a polynucleotide chain, which enhances zinc-induced binding to DNA.

  15. Impact of arterial occlusion during partial nephrectomy on residual renal function. An evaluation with {sup 99m}technetium-dimercaptosuccinic acid scintigraphy

    Energy Technology Data Exchange (ETDEWEB)

    Kondo, Tsunenori; Nakazawa, Hayakazu; Ito, Fumio; Onitsuka, Shiro; Ryoji, Osamu; Yago, Rie; Hashimoto, Yasunobu; Toma, Hiroshi [Tokyo Women' s Medical Coll. (Japan)

    2002-08-01

    Partial nephrectomy (PNx) has been performed with temporary renal arterial occlusion and in situ renal hypothermia (conventional PNx). However, the impact of temporary renal arterial occlusion on residual renal function has not been well assessed. To address this question, we performed renal scintigraphy with {sup 99m}technetium-dimercaptosuccinic acid (DMSA) for the quantitative measurement of postoperative residual renal function after conventional PNx and partial nephrectomy without arterial occlusion (non-clamping PNx). Thirty-four patients underwent postoperative DMSA scintigraphy after PNx for renal cell carcinoma. No obvious difference in preoperative renal function between the diseased kidney and the contralateral kidney was found in any of the patients. Of these patients, 24 underwent conventional PNx, and 10 underwent non-clamping PNx. Residual renal function was evaluated using the relative DMSA uptake of the operated kidney. The relative DMSA uptake of the operated kidney was 39.9{+-}7.3% (25.1-58.8) after conventional PNx compared to 34.8{+-}8.9% (13.5-45.5) after non-clamping PNx. This difference was not statistically significant (P=0.15). Total ischemic time during conventional PNx had no adverse influence on the residual renal function. In the analysis of the other determinant factors influencing residual renal function, tumor size was the only significant factor that inversely correlated with the relative DMSA uptake. Our results showed that arterial clamping during PNx has no negative impact on the functional residual capacity as long as in situ renal hypothermia is adequately performed. (author)

  16. Membrane topology of the electrogenic aspartate-alanine antiporter AspT of Tetragenococcus halophilus.

    Science.gov (United States)

    Nanatani, Kei; Ohonishi, Fumito; Yoneyama, Hiroshi; Nakajima, Tasuku; Abe, Keietsu

    2005-03-01

    AspT is an electrogenic aspartate:alanine exchange protein that represents the vectorial component of a proton-motive metabolic cycle found in some strains of Tetragenococcus halophilus. AspT is the sole member of a new family, the Aspartate: Alanine Exchanger (AAE) family, in secondary transporters, according to the computational classification proposed by Saier et al. (http://www.biology.ucsd.edu/~msaier/transport/). We analyzed the topology of AspT biochemically, by using fusion methods in combination with alkaline phosphatase or beta-lactamase. These results suggested that AspT has a unique topology; 8 TMS, a large cytoplasmic loop (183 amino acids) between TMS5 and TMS6, and N- and C-termini that both face the periplasm. These results demonstrated a unique 2D-structure of AspT as the novel AAE family. PMID:15670744

  17. Seed-specific aspartic proteinase FeAP12 from buckwheat (Fagopyrum esculentum Moench

    Directory of Open Access Journals (Sweden)

    Timotijević Gordana S.

    2010-01-01

    Full Text Available Aspartic proteinase gene (FeAP12 has been isolated from the cDNA library of developing buckwheat seeds. Analysis of its deduced amino acid sequence showed that it resembled the structure and shared high homology with typical plant aspartic proteinases (AP characterized by the presence of a plant-specific insert (PSI, unique among APs. It was shown that FeAP12 mRNA was not present in the leaves, roots, steam and flowers, but was seed-specifically expressed. Moreover, the highest levels of FeAP12 expression were observed in the early stages of seed development, therefore suggesting its potential role in nucellar degradation.

  18. Existence of an Endogenous Glutamate and Aspartate Transporter in Chinese Hamster Ovary Cells

    Institute of Scientific and Technical Information of China (English)

    Xunhe JI; Yuhua JIN; Yaoyue CHEN; Chongyong LI; Lihe GUO

    2007-01-01

    Chinese hamster ovary cells show endogenous high-affinity Na+-dependent glutamate transport activity. This transport activity is kinetically similar to a glutamate transporter family strategically expressed in the central nervous system and is pharmacologically unlike glutamate transporter-1 or excitatory amino acid carrier 1. The cDNA of a glutamate/aspartate transporter (GLAST)-like transporter was obtained and analyzed. The deduced amino acid sequence showed high similarity to human, mouse, and rat GLAST. We concluded that a GLAST-like glutamate transporter exists in Chinese hamster ovary cells that might confer the endogenous high-affinity Na+-dependent glutamate transport activity evident in these cells.

  19. Distinguishing of Ile/Leu amino acid residues in the PP3 protein by (hot) electron capture dissociation in Fourier transform ion cyclotron resonance mass spectrometry

    DEFF Research Database (Denmark)

    Kjeldsen, Frank; Haselmann, Kim F; Sørensen, Esben Skipper;

    2003-01-01

    In hot electron capture dissociation (HECD), multiply protonated polypeptides fragment upon capturing approximately 11-eV electrons. The excess of energy upon the primary c, z* cleavage induces secondary fragmentation in z* fragments. The resultant w ions allow one to distinguish between the isom......In hot electron capture dissociation (HECD), multiply protonated polypeptides fragment upon capturing approximately 11-eV electrons. The excess of energy upon the primary c, z* cleavage induces secondary fragmentation in z* fragments. The resultant w ions allow one to distinguish between...... the isomeric Ile and Leu residues. The analytical utility of HECD is evaluated using tryptic peptides from the bovine milk protein PP3 containing totally 135 amino acid residues. Using a formal procedure for Ile/Leu (Xle) residue assignment, the identities of 20 out of 25 Xle residues (80%) were determined...... such acquisitions. Unlike the case of high-energy collision-induced dissociation, no d ions were observed in the HECD of tryptic peptides....

  20. Mapping of amino acid residues responsible for adhesion of cell culture-adapted foot-and-mouth disease SAT type viruses.

    Science.gov (United States)

    Maree, Francois F; Blignaut, Belinda; de Beer, Tjaart A P; Visser, Nico; Rieder, Elizabeth A

    2010-10-01

    Foot-and-mouth disease virus (FMDV) infects host cells by adhering to the alpha(V) subgroup of the integrin family of cellular receptors in a Arg-Gly-Asp (RGD) dependent manner. FMD viruses, propagated in non-host cell cultures are reported to acquire the ability to enter cells via alternative cell surface molecules. Sequencing analysis of SAT1 and SAT2 cell culture-adapted variants showed acquisition of positively charged amino acid residues within surface-exposed loops of the outer capsid structural proteins. The fixation of positively charged residues at position 110-112 in the beta F-beta G loop of VP1 of SAT1 isolates is thought to correlate with the acquisition of the ability to utilise alternative glycosaminoglycan (GAG) molecules for cell entry. Similarly, two SAT2 viruses that adapted readily to BHK-21 cells accumulated positively charged residues at positions 83 and 85 of the beta D-beta E loop of VP1. Both regions surround the fivefold axis of the virion. Recombinant viruses containing positively charged residues at position 110 and 112 of VP1 were able to infect CHO-K1 cells (that expresses GAG) and demonstrated increased infectivity in BHK-21 cells. Therefore, recombinant SAT viruses engineered to express substitutions that induce GAG-binding could be exploited in the rational design of vaccine seed stocks with improved growth properties in cell cultures. PMID:20637812

  1. Identification of amino acid residues involved in substrate specificity of plant acyl-ACP thioesterases using a bioinformatics-guided approach

    Directory of Open Access Journals (Sweden)

    Mayer Kimberly M

    2007-01-01

    Full Text Available Abstract Background The large amount of available sequence information for the plant acyl-ACP thioesterases (TEs made it possible to use a bioinformatics-guided approach to identify amino acid residues involved in substrate specificity. The Conserved Property Difference Locator (CPDL program allowed the identification of putative specificity-determining residues that differ between the FatA and FatB TE classes. Six of the FatA residue differences identified by CPDL were incorporated into the FatB-like parent via site-directed mutagenesis and the effect of each on TE activity was determined. Variants were expressed in E. coli strain K27 that allows determination of enzyme activity by GCMS analysis of fatty acids released into the medium. Results Substitutions at four of the positions (74, 86, 141, and 174 changed substrate specificity to varying degrees while changes at the remaining two positions, 110 and 221, essentially inactivated the thioesterase. The effects of substitutions at positions 74, 141, and 174 (3-MUT or 74, 86, 141, 174 (4-MUT were not additive with respect to specificity. Conclusion Four of six putative specificity determining positions in plant TEs, identified with the use of CPDL, were validated experimentally; a novel colorimetric screen that discriminates between active and inactive TEs is also presented.

  2. Ab Initio MD Simulations of the Brønsted Acidity of Glutathione in Aqueous Solutions: Predicting pKa Shifts of the Cysteine Residue.

    Science.gov (United States)

    Tummanapelli, Anil Kumar; Vasudevan, Sukumaran

    2015-12-10

    The tripeptide glutathione (GSH) is one of the most abundant peptides and the major repository for nonprotein sulfur in both animal and plant cells. It plays a critical role in intracellular oxidative stress management by the reversible formation of glutathione disulfide with the thiol-disulfide pair acting as a redox buffer. The state of charge of the ionizable groups of GSH can influence the redox couple, and hence the pKa value of the cysteine residue of GSH is critical to its functioning. Here we report ab initio Car-Parrinello molecular dynamics simulations of glutathione solvated by 200 water molecules, all of which are considered in the simulation. We show that the free-energy landscape for the protonation-deprotonation reaction of the cysteine residue of GSH computed using metadynamics sampling provides accurate estimates of the pKa and correctly predicts the shift in the dissociation constant values as compared with the isolated cysteine amino acid.

  3. 常压渣油及其悬浮床加氢尾油中的酸性含氧化合物%Acid Oxygenated Compounds in Residue and Slurry-Bed Hydrocracking Cracked Residue

    Institute of Scientific and Technical Information of China (English)

    文萍; 李传; 李庶峰; 邓文安

    2011-01-01

    以克拉玛依炼油厂常压渣油为原料,在重质油加氢实验室中试装置进行悬浮床加氢反应:反应时间为1h,催化荆质量分数为800 μg/g,反应温度分别为410,430,440℃.对反应后产物进行常减压蒸馏.采用柱色谱法对克炼常渣及其悬浮床加氢尾油进行四组分分离,测定了各组分的酸值,考察了常压渣油及其悬浮床加氢尾油中酸性含氧化合物的分布情况.研究结果表明,克炼常渣中的酸性含氧化合物主要分布在胶质中;克炼常渣悬浮床加氢尾油中的酸性含氧化合物主要分布在胶质和沥青质中.%Karamay atmospheric residue(KLAR) was hydrocracked in pilot experimental device of state key laboratory of heavy oil processing, with the presence of an oil - soluble catalyst. Reaction time was set to 1 h and reaction catalyst concentration at 800 μg/g, reaction temperature were 410,430 and 450 ℃. Then KLAR and its slurry-bed hydrocracking cracked residue were separated into four fractions. The acid number in each fraction was determined. The distribution of the acid oxygenated compounds in each material was obtained. The results show that the acid oxygenated compounds in KLAR are mainly distributed in resin, which in slurry-bed hydrocracking cracked residue of KLAR are mainly distributed in resin and asphaltene.

  4. Copper Leaching from Copper Residue with Oxygen in Sulfuric Acid/Chloride Solution DENG Tong 1,%在硫酸/氯化物深液中用氧气浸出铜渣中的铜

    Institute of Scientific and Technical Information of China (English)

    邓彤; 文震

    2000-01-01

    Leaching of a copper residue, produced by selected oxidation leaching of a nickel matte, in oxygenated sulfuric acid solution with the participation of chloride was investigated. The effects of quantity of chloride, flowrate of oxygen, concentration of sulfuric acid and temperature were discussed as leaching variables. Addition of chloride in small amount into the leach slurry was justified in enhancing copper leaching from the residue.

  5. Advanced treatment of residual nitrogen from biologically treated coke effluent by a microalga-mediated process using volatile fatty acids (VFAs) under stepwise mixotrophic conditions.

    Science.gov (United States)

    Ryu, Byung-Gon; Kim, Woong; Heo, Sung-Woon; Kim, Donghyun; Choi, Gang-Guk; Yang, Ji-Won

    2015-09-01

    This work describes the development of a microalga-mediated process for simultaneous removal of residual ammonium nitrogen (NH4(+)-N) and production of lipids from biologically treated coke effluent. Four species of green algae were tested using a sequential mixotrophic process. In the first phase-CO2-supplied mixotrophic condition-all microalgae assimilated NH4(+)-N with no evident inhibition. In second phase-volatile fatty acids (VFAs)-supplied mixotrophic condition-removal rates of NH4(+)-N and biomass significantly increased. Among the microalgae used, Arctic Chlorella sp. ArM0029B had the highest rate of NH4(+)-N removal (0.97 mg/L/h) and fatty acid production (24.9 mg/L/d) which were 3.6- and 2.1-fold higher than those observed under the CO2-supplied mixotrophic condition. Redundancy analysis (RDA) indicated that acetate and butyrate were decisive factors for increasing NH4(+)-N removal and fatty acid production. These results demonstrate that microalgae can be used in a sequential process for treatment of residual nitrogen after initial treatment of activated sludge. PMID:25881553

  6. Direct fermentation of potato starch and potato residues to lactic acid by Geobacillus stearothermophilus under non-sterile conditions

    OpenAIRE

    Smerilli, Marina; Neureiter, Markus; Wurz, Stefan; Haas, Cornelia; Frühauf, Sabine; Fuchs, Werner

    2015-01-01

    BACKGROUND Lactic acid is an important biorefinery platform chemical. The use of thermophilic amylolytic microorganisms to produce lactic acid by fermentation constitutes an efficient strategy to reduce operating costs, including raw materials and sterilization costs. RESULTS A process for the thermophilic production of lactic acid by Geobacillus stearothermophilus directly from potato starch was characterized and optimized. Geobacillus stearothermophilus DSM 494 was selected out of 12 strain...

  7. Replacement of the N-terminal tyrosine residue in opioid peptides with 3-(2,6-dimethyl-4-carbamoylphenyl)propanoic acid (Dcp) results in novel opioid antagonists.

    Science.gov (United States)

    Lu, Yixin; Lum, Tze Keong; Leow Augustine, Yoon Wui; Weltrowska, Grazyna; Nguyen, Thi M-D; Lemieux, Carole; Chung, Nga N; Schiller, Peter W

    2006-08-24

    3-(2,6-Dimethyl-4-carbamoylphenyl)propanoic acid (Dcp), a 2',6'-dimethyltyrosine analogue containing a carbamoyl group in place of the hydroxyl function and lacking the amino group, was synthesized. The replacement of Tyr1 in an enkephalin analogue and in dynorphin A(1-11)-NH2 with Dcp resulted in the first opioid peptide-derived antagonists that do not contain a phenolic hydroxyl group at the 1-position residue. The cyclic peptide Dcp-c[D-Cys-Gly-Phe(pNO2)-D-Cys]NH2 represents a novel, potent mu opioid antagonist. PMID:16913729

  8. TmiRUSite and TmiROSite scripts: searching for mRNA fragments with miRNA binding sites with encoded amino acid residues

    OpenAIRE

    Berillo, Olga; Régnier, Mireille; Ivashchenko, Anatoly

    2014-01-01

    microRNAs are small RNA molecules that inhibit the translation of target genes. microRNA binding sites are located in the untranslated regions as well as in the coding domains. We describe TmiRUSite and TmiROSite scripts developed using python as tools for the extraction of nucleotide sequences for miRNA binding sites with their encoded amino acid residue sequences. The scripts allow for retrieving a set of additional sequences at left and at right from the binding site. The scripts presents ...

  9. Immobilization by Polyurethane of Pseudomonas dacunhae Cells Containing l-Aspartate β-Decarboxylase Activity and Application to l-Alanine Production

    Science.gov (United States)

    Fusee, Murray C.; Weber, Jennifer E.

    1984-01-01

    Whole cells of Pseudomonas dacunhae containing l-aspartate β-decarboxylase activity were immobilized by mixing a cell suspension with a liquid isocyanate-capped polyurethane prepolymer (Hypol; W. R. Grace & Co., Lexington, Mass.). The immobilized cell preparation was used to convert l-aspartic acid to l-alanine. Properties of the immobilized P. dacunhae cells containing aspartate β-decarboxylase activity were investigated with batch reactors. Retention of enzyme activity was observed to be as much as 100% when cell lysis was allowed to occur before immobilization. The pH and temperature optima were determined to be 5.5 and 45°C, respectively. Immobilized P. dacunhael-aspartate β-decarboxylase activity was stabilized by the addition of 0.1 mM pyridoxal-5-phosphate and 0.1 mM α-ketoglutaric acid to a 1.7 M ammonium aspartate (pH 5.5) substrate solution. Under conditions of semicontinuous use in a batch reactor, a 2.5% loss in immobilized l-aspartate β-decarboxylase activity was observed over a 31-day period. PMID:16346636

  10. Forensic applications of sodium rhodizonate and hydrochloric acid: a new histological technique for detection of gunshot residues.

    Science.gov (United States)

    Andreola, Salvatore; Gentile, Guendalina; Battistini, Alessio; Cattaneo, Cristina; Zoja, Riccardo

    2011-05-01

    Demonstration of the presence of lead residues deriving from gunshot in skin and underlying tissues is essential for the correct forensic analysis of numerous legal cases. Optical microscopy remains the fastest, cheapest diagnostic technique, even though its sensitivity and specificity are poor because of the scarce quantity of histological tissue that can be examined and possible environmental lead pollution. To confirm the presence of lead from gunshot residues, we applied to histological sections of human skin a technique proposed by Owens and George in 1991 for macroscopic detection of lead on the clothing of shooting victims, involving a reaction with sodium rhodizonate and subsequent confirmation by color change on application of HCl. Our results demonstrate the technical possibility of using this macroscopic technique even on histological samples and support the need for further studies on a larger series of cases correlated with the type of ammunition and firing distance. PMID:21521219

  11. Conformational study reveals amino acid residues essential for hemagglutinating and anti-proliferative activities of Clematis montana lectin.

    Science.gov (United States)

    Lu, Bangmin; Zhang, Bin; Qi, Wei; Zhu, Yanan; Zhao, Yan; Zhou, Nan; Sun, Rong; Bao, Jinku; Wu, Chuanfang

    2014-11-01

    Clematis montana lectin (CML), a novel mannose-binding lectin purified from C. montana Buch.-Ham stem (Ranunculaceae), has been proved to have hemagglutinating activity in rabbit erythrocytes and apoptosis-inducing activity in tumor cells. However, the biochemical properties of CML have not revealed and its structural information still needs to be elucidated. In this study, it was found that CML possessed quite good thermostability and alkaline resistance, and its hemagglutinating activity was bivalent metal cation dependent. In addition, hemagglutination test and fluorescence spectroscopy proved that GuHCl, urea, and sodium dodecyl sulfate could change the conformation of CML and further caused the loss of hemagglutination activity. Moreover, the changes of fluorescence spectrum indicated that the tryptophan (Trp) microenvironment conversion might be related to the conformation and bioactivities of CML. In addition, it was also found that Trp residues, arginine (Arg) residues, and sulfhydryl were important for the hemagglutinating activity of CML, but only Trp was proved to be crucial for the CML conformation. Furthermore, the Trp, Arg, and sulfhydryl-modified CML exhibited 97.17%, 76.99%, and 49.64% loss of its anti-proliferative activity, respectively, which was consistent with the alterations of its hemagglutinating activity. Given these findings, Trp residues on the surface of CML are essential for the active center to form substrate-accessible conformation and suitable environment for carbohydrate binding. PMID:25239139

  12. Role of certain amino acid residues of the coelenterazine-binding cavity in bioluminescence of light-sensitive Ca(2+)-regulated photoprotein berovin.

    Science.gov (United States)

    Burakova, Ludmila P; Stepanyuk, Galina A; Eremeeva, Elena V; Vysotski, Eugene S

    2016-05-11

    Bright bioluminescence of ctenophores is caused by Ca(2+)-regulated photoproteins. Although these photoproteins are functionally identical to and share many properties of cnidarian photoproteins, like aequorin and obelin, and retain the same spatial architecture, they are extremely sensitive to light, i.e. lose the ability to bioluminesce on exposure to light over the entire absorption spectrum. In addition, the degree of identity of their amino acid sequences with those of cnidarian photoproteins is only 29.4%. This suggests that the residues involved in bioluminescence of ctenophore and cnidarian photoproteins significantly differ. Here we describe the bioluminescent properties of berovin mutants with substitution of the residues located in the photoprotein internal cavity. Since the spatial structure of berovin bound with a substrate is not determined yet, to identify these residues we have modeled it with an accommodated substrate using the structures of some cnidarian Ca(2+)-regulated photoproteins with bound coelenterazine or coelenteramide as templates in order to obtain an adequate sampling and to take into account all possible conformers and variants for ligand-protein docking. Based on the impact of substitutions on the bioluminescent properties and model structures we speculate that within the internal cavity of ctenophore photoproteins, coelenterazine is bound as a 2-peroxy anion adduct which is stabilized owing to Coulomb interaction with a positively charged guanidinium group of Arg41 paired with Tyr204. In this case, the bioluminescence reaction is triggered by only calcium-induced conformational changes leading to the disturbance of charge-charge interaction.

  13. Intramolecular signal transmission in enterobacterial aspartate transcarbamylases II. Engineering co-operativity and allosteric regulation in the aspartate transcarbamylase of Erwinia herbicola.

    Science.gov (United States)

    Cunin, R; Rani, C S; Van Vliet, F; Wild, J R; Wales, M

    1999-12-17

    The aspartate transcarbamylase (ATCase) from Erwinia herbicola differs from the other investigated enterobacterial ATCases by its absence of homotropic co-operativity toward the substrate aspartate and its lack of response to ATP which is an allosteric effector (activator) of this family of enzymes. Nevertheless, the E. herbicola ATCase has the same quaternary structure, two trimers of catalytic chains with three dimers of regulatory chains ((c3)2(r2)3), as other enterobacterial ATCases and shows extensive primary structure conservation. In (c3)2(r2)3 ATCases, the association of the catalytic subunits c3 with the regulatory subunits r2 is responsible for the establishment of positive co-operativity between catalytic sites for the binding of aspartate and it dictates the pattern of allosteric response toward nucleotide effectors. Alignment of the primary sequence of the regulatory polypeptides from the E. herbicola and from the paradigmatic Escherichia coli ATCases reveals major blocks of divergence, corresponding to discrete structural elements in the E. coli enzyme. Chimeric ATCases were constructed by exchanging these blocks of divergent sequence between these two ATCases. It was found that the amino acid composition of the outermost beta-strand of a five-stranded beta-sheet in the effector-binding domain of the regulatory polypeptide is responsible for the lack of co-operativity and response to ATP of the E. herbicola ATCase. A novel structural element involved in allosteric signal recognition and transmission in this family of ATCases was thus identified. PMID:10600394

  14. DNA聚合酶中宿主细胞核酸残留的分析%Analysis of residual host cell nucleic acid in DNA polymerase

    Institute of Scientific and Technical Information of China (English)

    刘金华; 吴月丹; 史艳宇; 刘阳; 吴连鹏

    2012-01-01

    Objective To analyze the residual host cell nucleic acid in commercial DNA polymerase products manufactured by various manufacturers. Methods A Taqman probe-based real-time PCR method was developed by using the specific primers and probes designed according to E. coli 16S rRNA gene sequence, and used for analysis of residual E. coli DNA in recombinant products. Results Residual E. coli DNAs were detected in all the DNA polymerase products manufactured by various manufacturers by the developed real-time PCR, of which the contents were different. Conclusion When recombinant products especially those prepared with E. coli were tested by PCR, the effect of residual host cell nucleic acid in DNA polymerase on test result should be paid more attention. It suggested that the Ct value of real-time PCR for quantitative determination should be controlled to 30 or below so as to minimize the effect of background residue of DNA polymerase.%目的 分析市售不同厂家DNA聚合酶中的宿主细胞核酸残留.方法 根据E coli 16S rRNA基因序列设计特异引物及探针,建立基于Taqman探针技术的Real-time PCR检测方法,检测基因工程制品中E.coli的核酸残留.结果 建立的Real-time PCR法检测市售不同厂家的DNA聚合酶中均有宿主细胞E.coli核酸残留,但不同来源的DNA聚合酶其宿主细胞核酸残留量不同.结论 应用PCR方法检测基因工程产品,尤其是E.coli制备的生物制品时,应注意DNA聚合酶中核酸残留对检测结果的影响;应用Real time PCR法定量检测时,建议将Ct值控制在30以内,以减小DNA聚合酶背景残留物的影响.

  15. 一种肝脏类生物相容性氨基酸共聚物磁共振成像造影剂%A Biocompatible Gadolinium (III)-Poly (Aspartic Acid-Co-Phenylalanine) for Liver Magnetic Resonance Imaging Contrast Agent

    Institute of Scientific and Technical Information of China (English)

    肖研; 湛游洋; 薛蓉; 李晓晶; 裴奉奎; 冯江华; 占博涵

    2015-01-01

    A new biocompatible gadolinium (III)-macromolecule (AP-EDA-DOTA-Gd) was developed as a magnetic resonance imaging (MRI) contrast agent. Poly (aspartic acid-co- phenylalanine) was synthesized, modified via ethylenediamine, conjugated with 1,4,7,10- tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) and finally chelated gadolinium (III), yielding gadolinium (III)-based macromolecule (AP-EDA-DOTA-Gd). The hemolytic tests showed the hemocompatibility of this gadolinium (III)-based macromolecular conjugate.In vitro, AP-EDA-DOTA-Gd could be degraded, when it was incubated with cathepsin B in phosphate buffered solution (pH = 5.5). TheT1-relaxivity (15.95 mmol–1·L·s–1) of AP-EDA-DOTA-Gd was 2.9 times of that (5.59 mmol–1·L·s–1) of the clinical MRI contrast agent (Gd-DOTA) at 1.5 T and 25℃. The liver enhancement of AP-EDA-DOTA-Gd was 63.5±6.1% during the maximum enhancement time (50-80 min), which was much better than that of Gd-DOTA (24.2±2.9%, 10-30 min). AP-EDA-DOTA-Gd was expected to be a potential liver MRI contrast agent.%一种新型的以天门冬氨酸-苯丙氨酸共聚物为载体的大分子生物相容性材料(AP-EDA-DOTA-Gd)被制备出来作为磁共振成像造影剂.首先合成了天门冬氨酸-苯丙氨酸共聚物,之后利用乙二胺将1,4,7,10-四氮杂环十二烷-1,4,7,10-四乙酸(DOTA)连接到共聚物上,最后将钆离子通过配位的作用方式连接到 DOTA 上,最终得到大分子AP-EDA-DOTA-Gd.体外溶血性试验表明AP-EDA-DOTA-Gd具有较好的血液相容性.在pH =5.5的组织蛋白酶B的磷酸缓冲液中,AP-EDA-DOTA-Gd能够降解.AP- EDA-DOTA-Gd的体外弛豫效率(15.95 mmol–1×L×s–1)为目前临床应用的Gd-DOTA (5.59 mmol–1×L×s–1)的2.9倍.大鼠肝脏成像实验结果表明,AP-EDA-DOTA-Gd对于肝组织的成像增强对比度为63.5±6.1%远高于Gd-DOTA (24.2±2.9%).

  16. THE EFFECTS OF ZINC DEFICIENCY ON THE CONCENTRATION OF BRAIN FREE AMINO ACIDS AND SYNAPTIC MEMBRANES N-METHYL-D-ASPARTATE RECEPTORS IN RATS%缺锌对大鼠脑组织游离氨基酸和突触膜 N-甲基-D-天冬氨酸受体含量的影响

    Institute of Scientific and Technical Information of China (English)

    刘燕强; 顾景范

    2003-01-01

    本研究进行了两系列实验以探讨缺锌对大鼠脑组织游离氨基酸和突触膜N-甲基-D-天冬氨酸受体含量的影响.在第一系列实验中,把生长大鼠随机分为三组即缺锌组(ZD)、对喂组(PF)和缺锌补锌组(ZS),分别饲喂低锌饲料(3.3mg/kg)、常锌饲料但给料量与缺锌组一致以及先饲喂缺锌饲料21d后再饲喂常锌饲料,持续饲喂35d.饲养实验结束后,采取脑组织样本以分析其中的游离氨基酸的含量.在第二系列实验中,第1和第2组的处理与实验1一致,而第3组则不限食地饲喂常锌饲料,持续饲喂28d.然后取海马组织以分析其中的NMDA受体的含量.结果表明,缺锌显著降低端脑中游离谷氨酸、牛磺酸、苏氨酸、丝氨酸、丙氨酸、半胱氨酸和精氨酸含量,同时使海马中NMDA受体的最大结合率降低.此结果可能与缺锌降低大鼠学习记忆功能有关.%Two experiments were used to evaluate the effects of zinc deficiency on the concentration of free amino acids and N-methyl-D-aspartate (NMDA) receptor. In Exp. 1, Growing rats respectively consumed a low zinc (3.3mg/kg) diet (ZD), the adequate zinc but restricted according to feed consumption of ZD group (PF) or an adequate zinc diet after a low zinc diet for 21d(ZS). The duration is 35d. The telencephalon tissues were used for free amino acid concentration analysis. In Exp. 2, The treatment of group 1 and 2 were similar to Exp.1, but the rats of group 3 consumed adequate zinc diet ad libitum. The duration is 28d. The hippocampus tissues were used for NMDA receptor concentration analysis. Zinc deficiency significantly reduced the concentration of glutamate, taurine, threonine, serine, alanine, cysteine and arginine in telencephalon tissues,and Bmax of NMDA receptors in hippocampus tissues. The results provides a good explanation for low learning and memory ability in zinc deficient rats.

  17. Multi-residue analysis of 26 organochlorine pesticides in Alpinia oxyphylla by GC-ECD after solid phase extraction and acid cleanup.

    Science.gov (United States)

    Zhao, Xiangsheng; Zhou, Yakui; Kong, Weijun; Gong, Bao; Chen, Deli; Wei, Jianhe; Yang, Meihua

    2016-04-01

    A simple and effective multi-residue method was developed and validated for the analysis of 26 organochlorine pesticide residues in Alpinia oxyphylla by a gas chromatography with an electron capture detector (GC-ECD). The target pesticides were extracted by sonication and cleaned up with florisil solid phase extraction and sulphuric acid. Some crucial parameters, including extraction solvent and time, sorbent type, elute solvent and concentration of sulphuric acid were optimized to improve the performance of sample preparation procedure. The optimized method gave high sensitivity with detection limit ranging from 0.1 to 2.0μg/kg. Matrix-matched calibration was employed for the quantification, and a wide linear range (from 1.0 to 1000μg/kg) with r(2) values ranging from 0.9971 to 0.9998 was obtained. For the majority of the tested pesticides, the average recoveries were in acceptable range (between 70% and 110%) with relative standard deviation values below 15.0%. Matrix effect was evaluated for target compounds through the study of ratio of peak area obtained in the solvent and blank matrix. The proposed method was applied to simultaneously analyze 26 pesticides in 55 batches of Alpinia oxyphylla samples. 3 samples were found to be positive with four pesticides (α-BHC, quintozene, trans-chlordane and op'-DDD), which were confirmed by gas chromatography-mass spectrometry (GC-MS) in selective ion monitoring (SIM) mode. PMID:26990736

  18. Acid decomposition and thiourea leaching of silver from hazardous jarosite residues: Effect of some cations on the stability of the thiourea system.

    Science.gov (United States)

    Calla-Choque, D; Nava-Alonso, F; Fuentes-Aceituno, J C

    2016-11-01

    The recovery of silver from hazardous jarosite residues was studied employing thiourea as leaching agent at acid pH and 90°C. The stability of the thiourea in synthetic solutions was evaluated in the presence of some cations that can be present in this leaching system: cupric and ferric ions as oxidant species, and zinc, lead and iron as divalent ions. Two silver leaching methods were studied: the simultaneous jarosite decomposition-silver leaching, and the jarosite decomposition followed by the silver leaching. The study with synthetic solutions demonstrated that cupric and ferric ions have a negative effect on thiourea stability due to their oxidant properties. The effect of cupric ions is more significant than the effect of ferric ions; other studied cations (Fe(2+), Zn(2+), Pb(2+)) had no effect on the stability of thiourea. When the decomposition of jarosite and the silver leaching are carried out simultaneously, 70% of the silver can be recovered. When the acid decomposition was performed at pH 0.5 followed by the leaching step at pH 1, total silver recovery increased up to 90%. The zinc is completely dissolved with any of these processes while the lead is practically insoluble with these systems producing a lead-rich residue. PMID:27322901

  19. Residues in the extracellular loop 4 are critical for maintaining the conformational equilibrium of the gamma-aminobutyric acid transporter-1

    DEFF Research Database (Denmark)

    MacAulay, Nanna; Meinild, Anne-Kristine; Zeuthen, Thomas;

    2003-01-01

    We mutated residues Met345 and Thr349 in the rat gamma-aminobutyric acid transporter-1 (GAT-1) to histidines (M345H and T349H). These two residues are located four amino acids apart at the extracellular end of transmembrane segment 7 in a region of GAT-1 that we have previously suggested undergoes...... conformational changes critical for the transport process. The two single mutants and the double mutant (M345H/T349H) were expressed in Xenopus laevis oocytes, and their steady-state and presteady-state kinetics were examined and compared with wild type GAT-1 by using the two-electrode voltage clamp method...... affinity, a decrease in apparent Na+ affinity, a profound shift in the Q/Vm relationship to more negative potentials, and a decreased Li+-induced leak current. The data are consistent with a shift in the conformational equilibrium of the mutant transporters, with M345H stabilized in an outward...

  20. Two glutamic acid residues in the DNA-binding domain are engaged in the release of STAT1 dimers from DNA

    Directory of Open Access Journals (Sweden)

    Koch Verena

    2012-08-01

    Full Text Available Abstract Background In interferon-γ-stimulated cells, the dimeric transcription factor STAT1 (signal transducer and activator of transcription 1 recognizes semi-palindromic motifs in the promoter regions of cytokine-driven target genes termed GAS (gamma-activated sites. However, the molecular steps that facilitate GAS binding and the subsequent liberation of STAT1 homodimers from these promoter elements are not well understood. Results Using a mutational approach, we identified two critical glutamyl residues within the DNA-binding domain adjacent to the phosphodiester backbone of DNA which efficiently release phospho-STAT1 from DNA. The release of STAT1 dimers from DNA enhances transcriptional activity on both interferon-driven reporter and endogenous target genes. A substitution of either of the two glutamic acid residues broadens the repertoire of putative binding sites on DNA and enhances binding affinity to GAS sites. However, despite elevated levels of tyrosine phosphorylation and a prolonged nuclear accumulation period, the STAT1 DNA-binding mutants show a significantly reduced transcriptional activity upon stimulation of cells with interferon-γ. This reduced transcriptional response may be explained by the deposition of oligomerized STAT1 molecules outside GAS sites. Conclusions Thus, two negatively charged amino acid residues in the DNA-binding domain are engaged in the liberation of STAT1 from DNA, resulting in a high dissociation rate from non-GAS sites as a key feature of STAT1 signal transduction, which positively regulates cytokine-dependent gene expression probably by preventing retention at transcriptionally inert sites.

  1. Production of bio-oil rich in acetic acid and phenol from fast pyrolysis of palm residues using a fluidized bed reactor: Influence of activated carbons.

    Science.gov (United States)

    Jeong, Jae-Yong; Lee, Uen-Do; Chang, Won-Seok; Jeong, Soo-Hwa

    2016-11-01

    In this study, palm residues were pyrolyzed in a bench-scale (3kg/h) fast pyrolysis plant equipped with a fluidized bed reactor and bio-oil separation system for the production of bio-oil rich in acetic acid and phenol. Pyrolysis experiments were performed to investigate the effects of reaction temperature and the types and amounts of activated carbon on the bio-oil composition. The maximum bio-oil yield obtained was approximately 47wt% at a reaction temperature of 515°C. The main compounds produced from the bio-oils were acetic acid, hydroxyacetone, phenol, and phenolic compounds such as cresol, xylenol, and pyrocatechol. When coal-derived activated carbon was applied, the acetic acid and phenol yields in the bio-oils reached 21 and 19wt%, respectively. Finally, bio-oils rich in acetic acid and phenol could be produced separately by using an in situ bio-oil separation system and activated carbon as an additive.

  2. Radioimmunoassay of aspartate aminotransferase isoenzymes in human serum

    Energy Technology Data Exchange (ETDEWEB)

    Leung, F.Y.; Niblock, A.E.; Henderson, A.R.

    1984-08-01

    A description is given of the development of a sensitive, specific radioimmunoassay for the cytoplasmic and mitochondrial isoenzymes of human aspartate aminotransferase (L-aspartate:2-oxoglutarate aminotransferase; EC 2.6.1.1). Isoenzymes from human heart tissue were purified to homogeneity and used to raise high-titer antisera in rabbits. The antisera were partly purified by selective column chromatography. The Bolton-Hunter reagent was used to radioiodinate the isoenzymes. The assay requires 100 microL of serum, includes a solid-phase second-antibody separation, and can be completed in less than 3 h. There was no cross reactivity between the two isoenzymes. As little as 5 micrograms (50 pmol) of each aspartate aminotransferase can be measured per liter of serum.

  3. Toxoplasma gondii aspartic protease 1 is not essential in tachyzoites.

    Science.gov (United States)

    Polonais, Valerie; Shea, Michael; Soldati-Favre, Dominique

    2011-08-01

    Aspartic proteases are important virulence factors for pathogens and are recognized as attractive drug targets. Seven aspartic proteases (ASPs) have been identified in Toxoplasma gondii genome. Bioinformatics and phylogenetic analyses regroup them into five monophyletic groups. Among them, TgASP1, a coccidian specific aspartic protease related to the food vacuole plasmepsins, is associated with the secretory pathway in non-dividing cells and relocalizes in close proximity to the nascent inner membrane complex (IMC) of daughter cells during replication. Despite a potential role for TgASP1 in IMC formation, the generation of a conventional knockout of the TgASP1 gene revealed that this protease is not required for T. gondii tachyzoite survival or for proper IMC biogenesis.

  4. Crystal structure of a putative aspartic proteinase domain of the Mycobacterium tuberculosis cell surface antigen PE_PGRS16☆

    Science.gov (United States)

    Barathy, Deivanayaga V.; Suguna, Kaza

    2013-01-01

    We report the crystal structure of the first prokaryotic aspartic proteinase-like domain identified in the genome of Mycobacterium tuberculosis. A search in the genomes of Mycobacterium species showed that the C-terminal domains of some of the PE family proteins contain two classic DT/SG motifs of aspartic proteinases with a low overall sequence similarity to HIV proteinase. The three-dimensional structure of one of them, Rv0977 (PE_PGRS16) of M. tuberculosis revealed the characteristic pepsin-fold and catalytic site architecture. However, the active site was completely blocked by the N-terminal His-tag. Surprisingly, the enzyme was found to be inactive even after the removal of the N-terminal His-tag. A comparison of the structure with pepsins showed significant differences in the critical substrate binding residues and in the flap tyrosine conformation that could contribute to the lack of proteolytic activity of Rv0977. PMID:23923105

  5. An isozyme of the NADP-malic enzyme of a CAM plant, Aloe arborescens, with variation on conservative amino acid residues.

    Science.gov (United States)

    Honda, H; Akagi, H; Shimada, H

    2000-02-01

    In Aloe arborescens, an obligate CAM plant, Western analysis detected three major isoforms of NADP-malic enzyme (NADP-ME), 72kDa with a pI of 6.0, 65kDa with a pI of 5.6 and 65kDa with a pI of 5.5. Among them, the 65kDa protein with a pI of 5.5 was leaf-specific, and the 65kDa protein with a pI of 5.6 was found only in roots, whereas the 72kDa protein was uniformly detected in both organs. Activity staining indicated enzyme activity of both 65kDa NADP-MEs but little activity of the 72kDa protein. A cDNA clone encoding a leaf-abundant NADP-ME, AME1, was isolated. Deduced amino acid sequence of AME1 showed a high degree of homology to known NADP-MEs, but it was also found that AME1 contained substitutions on five conservative amino acid residues, some of which have been predicted to be important for their enzyme activity. Transgenic rice carrying the aloe AME1 gene efficiently produced an additional 65kDa protein with a pI of 5.5 as an active NADP-ME. These results indicate that AME1 corresponds to the leaf-specific 65kDa NADP-ME, which may be involved in CAM photosynthesis. It was also shown that substitutions of these conservative amino acid residues identified in AME1 still allowed it to give enzyme activity. PMID:10675616

  6. Engineering of halophilic enzymes: Two acidic amino acid residues at the carboxy-terminal region confer halophilic characteristics to Halomonas and Pseudomonas nucleoside diphosphate kinases

    OpenAIRE

    Tokunaga, Hiroko; Arakawa, Tsutomu; Tokunaga, Masao

    2008-01-01

    Nucleoside diphosphate kinase from Halomonas sp. 593 (HaNDK) exhibits halophilic characteristics. Residues 134 and 135 in the carboxy-terminal region of HaNDK are Glu–Glu, while those of its homologous counterpart of non-halophilic Pseudomonas NDK (PaNDK) are Ala–Ala. The double mutation, E134A-E135A, in HaNDK results in the loss of the halophilic characteristics, and, conversely, the double mutation of A134E-A135E in PaNDK confers halophilic characters to this enzyme, indicating that the cha...

  7. Effect of Wendan Decoction on Receptor of Glutamic Acid and N-methyl-D-aspartate in Rats with Schizophrenia%温胆汤对精神分裂症模型鼠海马谷氨酸和N-甲基-D-天冬门氨酸受体亚单位表达的影响

    Institute of Scientific and Technical Information of China (English)

    杨翠萍; 蔡长春; 杨晓金; 万红娇; 肖纯

    2011-01-01

    Objective:To explore the effect of Wendan Decoction (WDD) on the receptor of glutamic acid (Glu) and N-methyl-D-aspartate (NMDA) in rats with schizophrenia. Method: Thirty SD rats were divided randomly into 3 groups with 10 in each group: normal group (A), model group (B) and WDD group (C). WDD group was administered intragatrically with 20 g· kg -1WDD;the other groups were administered the same volume of normal saline (20 mL·kg-1). The 3 groups were treated for 21 days. Except the normal group, the other groups were given MK801 with sinistro-intraperitoneal injection to set the schizophrenia model after 1 hour of intragastrical administration in the last 3 days. The dosage was 0. 1 mL per 20 g. By the changes in immunohistochemistry and neuropathological morphology, we observed the influence of WDD on expression of receptor Glu in hippocampus,receptor subunit NR1 and NR2B of NMDA and protective effects on pathological injuries in hippocampus of the model rats. Result: The morphological observation showed that there were significant differences in expression of Glu, subunit NR1 and NR2B of NMDA receptor in all groups and there also were significant differences in cell structure and cell denaturalization of CA1 area in hippocampus. Conclusion: WDD can improve disorder of cell rearrangement, relieve the process of nuclei dissolution, postpone the denaturalization of hippocampus cell. It indicates WDD has certain protective effects on pathological injury in hippocampus of the model rats.%目的:观察温胆汤对精神分裂症模型鼠海马谷氨酸(Glu)和N-甲基-D-天冬门氨酸(NMDA)受体亚单位表达的影响.方法:将30只SD大鼠,随机分3组,每组10只,分别为正常组(A)、模型组(B)及温胆汤组(C),A,B组ig生理盐水20mL·kg-1,C组ig温胆汤20 g·kg-1,每天1次,21 d后地卓西平马来酸盐(MK801)ip诱发精神分裂症,造模3 d后,4 ℃ 4%多聚甲醛磷酸盐缓冲液大脑灌注固定、制备脑组织切片,免疫组化染色,观

  8. Filtrates & Residues. Acid Pickling with Amines: An Experiment in Applied Chemistry for High School or Freshman Chemistry.

    Science.gov (United States)

    Spears, Steven G.; And Others

    1988-01-01

    This article gives a brief description of the process of the removal of corrosion and millscale from the surfaces of ferrous metals by acid pickling. It suggests an experiment to illustrate this process including the procedure and a discussion of the results. (CW)

  9. MOLECULAR MODELING STUDY OF THE CONTRIBUTIONS OF SIDE AMINO ACID RESIDUES OF POLYMYXIN B3 TO ITS BINDING WITH E.COLI OUTER MEMBRANE LIPOPOLYSACCHARIDE

    Directory of Open Access Journals (Sweden)

    Lisnyak Yu. V.

    2014-12-01

    Full Text Available Last decades, antimicrobial peptides (AMPs are the subject of intense investigations aimed to develop effective drugs against extremely resistant nosocomial bacterial pathogens (especially Gram-negative bacteria. In particular, there has been greatly renewed interest to polymyxins, the representatives of AMPs which are specific and highly potent against Gram-negative bacteria, but have potential nephrotoxic side effect. A prerequisite of purposeful enhancement of therapeutic properties of polymyxins is a detailed knowledge of the molecular mechanisms of their interactions with cell targets. Lipopolysaccharide (LPS, the main component of the outer leaflet of outer membrane of gram-negative bacteria, is a primary cell target of polymyxins. The aim of the paper was to study the peculiarities of molecular interactions of polymyxin В3 with lipopolysaccharide of the outer membrane of gram-negative bacterium. Materials and methods The complexes of polymyxin В3 (PmВ3 and its alaninederivatives with E. coli outer membrane lipopolysaccharide were built and studied by molecular modeling methods (minimization, simulated annealing, docking. Atom coordinates of polymyxin В3 and LPS structures were taken from nuclear magnetic resonance and X-ray crystallography experiments, respectively. The AMBER03 force field was used with a 1.05 nm force cutoff. Longrange electrostatic interactions were treated by the Particle Mesh Ewald method. Results and discussion Alanine scanning of PmВ3 molecule has been carried out and the role of its side amino acid residues in the formation of complex with lipopolysaccharide has been investigated. It has been shown that substitutions of polymyxin’s Dab residues in positions 1, 3, 5, 8 and 9 for alanine markedly reduce the binding energy of PmB3-LPS complex, where as the similar substitutions of residues in positions 2, 6, 7 and 10 leave the binding energy virtually unchanged. Structural aspects of antimicrobial action of

  10. GC-based detection of aldononitrile acetate derivatized glucosamine and muramic acid for microbial residue determination in soil.

    Science.gov (United States)

    Liang, Chao; Read, Harry W; Balser, Teri C

    2012-01-01

    Quantitative approaches to characterizing microorganisms are crucial for a broader understanding of the microbial status and function within ecosystems. Current strategies for microbial analysis include both traditional laboratory culture-dependent techniques and those based on direct extraction and determination of certain biomarkers. Few among the diversity of microbial species inhabiting soil can be cultured, so culture-dependent methods introduce significant biases, a limitation absent in biomarker analysis. The glucosamine, mannosamine, galactosamine and muramic acid have been well served as measures of both the living and dead microbial mass, of these the glucosamine (most abundant) and muramic acid (uniquely from bacterial cell) are most important constituents in the soil systems. However, the lack of knowledge on the analysis restricts the wide popularization among scientific peers. Among all existing analytical methods, derivatization to aldononitrile acetates followed by GC-based analysis has emerged as a good option with respect to optimally balancing precision, sensitivity, simplicity, good chromatographic separation, and stability upon sample storage. Here, we present a detailed protocol for a reliable and relatively simple analysis of glucosamine and muramic acid from soil after their conversion to aldononitrile acetates. The protocol mainly comprises four steps: acid digestion, sample purification, derivatization and GC determination. The step-by-step procedure is modified according to former publications. In addition, we present a strategy to structurally validate the molecular ion of the derivative and its ion fragments formed upon electron ionization. We applied GC-EI-MS-SIM, LC-ESI-TOF-MS and isotopically labeled reagents to determine the molecular weight of aldononitrile acetate derivatized glucosamine and muramic acid; we used the mass shift of isotope-labeled derivatives in the ion spectrum to investigate ion fragments of each derivatives. In

  11. Influence of sodium chloride and weak organic acids (flux residues) on electrochemical migration of tin on surface mount chip components

    DEFF Research Database (Denmark)

    Verdingovas, Vadimas; Jellesen, Morten Stendahl; Ambat, Rajan

    2013-01-01

    The electrolytic properties of sodium chloride and no-clean solder flux residue, and their effects on electrochemical migration and dendrite growth on surface mount chip capacitors were investigated. The leakage current dependency on concentration of contaminants was measured by a solution...... conductivity method and compared with current measurements using DC voltage. The effect of electrolyte concentration and potential bias on the probability of electrochemical migration was investigated using a water droplet method on chip capacitors. The results from leakage current and conductivity measurement...... showed a difference which is caused by polarization effects, and demonstrated existing issues when indexing contamination levels on printed circuit board assemblies using a standardised solvent extract method. The experimental results showed that dendrite growth was dependent on the type and amount...

  12. Contribution of post-harvest agricultural paddy residue fires in the N.W. Indo-Gangetic Plain to ambient carcinogenic benzenoids, toxic isocyanic acid and carbon monoxide

    Science.gov (United States)

    Praphulla Chandra, Boggarapu; Sinha, Vinayak

    2016-04-01

    In the North West Indo-Gangetic Plain (N.W.IGP), large scale post-harvest paddy residue fires occur every year during the months of October-November. This anthropogenic perturbation causes contamination of the atmospheric environment with adverse impacts on regional air quality posing health risks for the population exposed to high concentrations of carcinogens such as benzene and toxic VOCs such as isocyanic acid. These gases and carbon monoxide are known to be emitted from biomass fires along with acetonitrile. Yet no long-term in-situ measurements quantifying the impact of this activity have been carried out in the N.W. IGP. Using high quality continuous online in-situ measurements of these gases at a strategic downwind site over a three year period from 2012 to 2014, we demonstrate the strong impact of this anthropogenic emission activity on ambient concentrations of these gases. In contrast to the pre-paddy harvest period, excellent correlation of benzenoids, isocyanic acid and CO with acetonitrile (a biomass burning chemical tracer); (r ≥ 0.82) and distinct VOC/acetonitrile emission ratios were observed for the post-paddy harvest period which was also characterized by high ambient concentrations of these species. The average concentrations of acetonitrile (1.62 ± 0.18 ppb), benzene (2.51 ± 0.28 ppb), toluene (3.72 ± 0.41 ppb), C8-aromatics (2.88 ± 0.30 ppb), C9-aromatics (1.55 ± 0.19 ppb) and CO (552 ± 113 ppb) in the post-paddy harvest periods were about 1.5 times higher than the annual average concentrations. For isocyanic acid, a compound with both primary and secondary sources, the concentration in the post-paddy harvest period was 0.97 ± 0.17 ppb. The annual average concentrations of benzene, a class A carcinogen, exceeded the annual exposure limit of 1.6 ppb at NTP mandated by the National Ambient Air Quality Standard of India (NAAQS). We show that mitigating the post-harvest paddy residue fires can lower the annual average concentration of

  13. Glutamic Acid at Residue 125 of the prM Helix Domain Interacts with Positively Charged Amino Acids in E Protein Domain II for Japanese Encephalitis Virus-Like-Particle Production

    OpenAIRE

    Peng, Jia-Guan; Wu, Suh-Chin

    2014-01-01

    Interaction between E and prM proteins in flavivirus-infected cells is a major factor for virus-like particle (VLP) production. The prM helical (prM-H) domain is topologically close to and may interact with domain II of the E protein (EDII). In this study, we investigated prM-H domain amino acid residues facing Japanese encephalitis virus EDII using site-directed mutagenesis to determine their roles in prM-E interaction and VLP production. Our results indicate that negatively charged prM-E125...

  14. Both foliar and residual applications of herbicides that inhibit amino acid biosynthesis induce alternative respiration and aerobic fermentation in pea roots.

    Science.gov (United States)

    Armendáriz, O; Gil-Monreal, M; Zulet, A; Zabalza, A; Royuela, M

    2016-05-01

    The objective of this work was to ascertain whether there is a general pattern of carbon allocation and utilisation in plants following herbicide supply, independent of the site of application: sprayed on leaves or supplied to nutrient solution. The herbicides studied were the amino acid biosynthesis-inhibiting herbicides (ABIH): glyphosate, an inhibitor of aromatic amino acid biosynthesis, and imazamox, an inhibitor of branched-chain amino acid biosynthesis. All treated plants showed impaired carbon metabolism; carbohydrate accumulation was detected in both leaves and roots of the treated plants. The accumulation in roots was due to lack of use of available sugars as growth was arrested, which elicited soluble carbohydrate accumulation in the leaves due to a decrease in sink strength. Under aerobic conditions, ethanol fermentative metabolism was enhanced in roots of the treated plants. This fermentative response was not related to a change in total respiration rates or cytochrome respiratory capacity, but an increase in alternative oxidase capacity was detected. Pyruvate accumulation was detected after most of the herbicide treatments. These results demonstrate that both ABIH induce the less-efficient, ATP-producing pathways, namely fermentation and alternative respiration, by increasing the key metabolite, pyruvate. The plant response was similar not only for the two ABIH but also after foliar or residual application.

  15. Ethanol production from residual wood chips of cellulose industry: acid pretreatment investigation, hemicellulosic hydrolysate fermentation, and remaining solid fraction fermentation by SSF process.

    Science.gov (United States)

    Silva, Neumara Luci Conceição; Betancur, Gabriel Jaime Vargas; Vasquez, Mariana Peñuela; Gomes, Edelvio de Barros; Pereira, Nei

    2011-04-01

    Current research indicates the ethanol fuel production from lignocellulosic materials, such as residual wood chips from the cellulose industry, as new emerging technology. This work aimed at evaluating the ethanol production from hemicellulose of eucalyptus chips by diluted acid pretreatment and the subsequent fermentation of the generated hydrolysate by a flocculating strain of Pichia stipitis. The remaining solid fraction generated after pretreatment was subjected to enzymatic hydrolysis, which was carried out simultaneously with glucose fermentation [saccharification and fermentation (SSF) process] using a strain of Saccharomyces cerevisiae. The acid pretreatment was evaluated using a central composite design for sulfuric acid concentration (1.0-4.0 v/v) and solid to liquid ratio (1:2-1:4, grams to milliliter) as independent variables. A maximum xylose concentration of 50 g/L was obtained in the hemicellulosic hydrolysate. The fermentation of hemicellulosic hydrolysate and the SSF process were performed in bioreactors and the final ethanol concentrations of 15.3 g/L and 28.7 g/L were obtained, respectively.

  16. Role of certain amino acid residues of the coelenterazine-binding cavity in bioluminescence of light-sensitive Ca(2+)-regulated photoprotein berovin.

    Science.gov (United States)

    Burakova, Ludmila P; Stepanyuk, Galina A; Eremeeva, Elena V; Vysotski, Eugene S

    2016-05-11

    Bright bioluminescence of ctenophores is caused by Ca(2+)-regulated photoproteins. Although these photoproteins are functionally identical to and share many properties of cnidarian photoproteins, like aequorin and obelin, and retain the same spatial architecture, they are extremely sensitive to light, i.e. lose the ability to bioluminesce on exposure to light over the entire absorption spectrum. In addition, the degree of identity of their amino acid sequences with those of cnidarian photoproteins is only 29.4%. This suggests that the residues involved in bioluminescence of ctenophore and cnidarian photoproteins significantly differ. Here we describe the bioluminescent properties of berovin mutants with substitution of the residues located in the photoprotein internal cavity. Since the spatial structure of berovin bound with a substrate is not determined yet, to identify these residues we have modeled it with an accommodated substrate using the structures of some cnidarian Ca(2+)-regulated photoproteins with bound coelenterazine or coelenteramide as templates in order to obtain an adequate sampling and to take into account all possible conformers and variants for ligand-protein docking. Based on the impact of substitutions on the bioluminescent properties and model structures we speculate that within the internal cavity of ctenophore photoproteins, coelenterazine is bound as a 2-peroxy anion adduct which is stabilized owing to Coulomb interaction with a positively charged guanidinium group of Arg41 paired with Tyr204. In this case, the bioluminescence reaction is triggered by only calcium-induced conformational changes leading to the disturbance of charge-charge interaction. PMID:27117544

  17. Developing an Acidic Residue Reactive and Sulfoxide-Containing MS-Cleavable Homobifunctional Cross-Linker for Probing Protein-Protein Interactions.

    Science.gov (United States)

    Gutierrez, Craig B; Yu, Clinton; Novitsky, Eric J; Huszagh, Alexander S; Rychnovsky, Scott D; Huang, Lan

    2016-08-16

    Cross-linking mass spectrometry (XL-MS) has become a powerful strategy for defining protein-protein interactions and elucidating architectures of large protein complexes. However, one of the inherent challenges in MS analysis of cross-linked peptides is their unambiguous identification. To facilitate this process, we have previously developed a series of amine-reactive sulfoxide-containing MS-cleavable cross-linkers. These MS-cleavable reagents have allowed us to establish a common robust XL-MS workflow that enables fast and accurate identification of cross-linked peptides using multistage tandem mass spectrometry (MS(n)). Although amine-reactive reagents targeting lysine residues have been successful, it remains difficult to characterize protein interaction interfaces with little or no lysine residues. To expand the coverage of protein interaction regions, we present here the development of a new acidic residue-targeting sulfoxide-containing MS-cleavable homobifunctional cross-linker, dihydrazide sulfoxide (DHSO). We demonstrate that DHSO cross-linked peptides display the same predictable and characteristic fragmentation pattern during collision induced dissociation as amine-reactive sulfoxide-containing MS-cleavable cross-linked peptides, thus permitting their simplified analysis and unambiguous identification by MS(n). Additionally, we show that DHSO can provide complementary data to amine-reactive reagents. Collectively, this work not only enlarges the range of the application of XL-MS approaches but also further demonstrates the robustness and applicability of sulfoxide-based MS-cleavability in conjunction with various cross-linking chemistries. PMID:27417384

  18. Aspartate Aminotransferase - Bridging Carbohydrate and Energy Metabolism in Plasmodium Falciparum

    NARCIS (Netherlands)

    Wrenger, Carsten; Mueller, Ingrid B.; Silber, Ariel M.; Jordanova, Rositsa; Lamzin, Victor S.; Groves, Matthew R.

    2012-01-01

    In this mini-review we briefly examine and summarize evidence on the role of the plasmodial aspartate aminotransferase (AspAT) of the malarial parasite. Recent data have provided information on the products of the purine salvage pathway as well as the glycolytic and oxidative phosphorylation pathway

  19. Regulation of N-methyl-D-aspartate receptor expression and N-methyl-D-aspartate-induced cellular response during chronic hypoxia in differentiated rat PC12 cells.

    Science.gov (United States)

    Kobayashi, S; Millhorn, D E

    2000-01-01

    The purpose of the present study was to examine the effect of chronic hypoxia on N-methyl-D-aspartate-mediated cellular responses in differentiated PC12 cells. PC12 cells were differentiated by treatment with nerve growth factor. Patch-clamp analysis in differentiated PC12 cells showed that extracellularly applied N-methyl-D-aspartate induced an inward current that was abolished by the presence of the N-methyl-D-aspartate receptor antagonist MK-801. Results from Ca(2+) imaging experiments showed that N-methyl-D-aspartate induced an elevation in intracellular free Ca(2+) which was also abolished by MK-801. We also examined the effect of hypoxia on the N-methyl-D-aspartate-induced current in nerve growth factor-treated cells. We found that the N-methyl-D-aspartate-induced inward current and the N-methyl-D-aspartate-induced elevation in intracellular free Ca(2+) were markedly attenuated by chronic hypoxia. We next examined the possibility that the reduced N-methyl-D-aspartate responsiveness was due to down-regulation of N-methyl-D-aspartate receptor levels. Northern blot and immunoblot analyses showed that both messenger RNA and protein levels for N-methyl-D-aspartate receptor subunit 1 were markedly decreased during hypoxia. However, the messenger RNA for N-methyl-D-aspartate receptor subunit 2C was increased, whereas the protein level for subunit 2C did not change. Our results indicate that differentiated PC12 cells express functional N-methyl-D-aspartate receptors and that chronic exposure to hypoxia attenuates the N-methyl-D-aspartate-induced Ca(2+) accumulation in these cells via down-regulation of N-methyl-D-aspartate receptor subunit 1. This mechanism may play an important role in protecting PC12 cells against hypoxic stress. PMID:11113364

  20. Amino acid residues involved in the catalytic mechanism of NAD-dependent glutamate dehydrogenase from Halobacterium salinarum.

    Science.gov (United States)

    Pérez-Pomares, F; Ferrer, J; Camacho, M; Pire, C; LLorca, F; Bonete, M J

    1999-02-01

    The pH dependence of kinetic parameters for a competitive inhibitor (glutarate) was determined in order to obtain information on the chemical mechanism for NAD-dependent glutamate dehydrogenase from Halobacterium salinarum. The maximum velocity is pH dependent, decreasing at low pHs giving a pK value of 7.19+/-0.13, while the V/K for l-glutamate at 30 degrees C decreases at low and high pHs, yielding pK values of 7.9+/-0.2 and 9.8+/-0.2, respectively. The glutarate pKis profile decreases at high pHs, yielding a pK of 9. 59+/-0.09 at 30 degrees C. The values of ionization heat calculated from the change in pK with temperature are: 1.19 x 10(4), 5.7 x 10(3), 7 x 10(3), 6.6 x 10(3) cal mol-1, for the residues involved. All these data suggest that the groups required for catalysis and/or binding are lysine, histidine and tyrosine. The enzyme shows a time-dependent loss in glutamate oxidation activity when incubated with diethyl pyrocarbonate (DEPC). Inactivation follows pseudo-first-order kinetics with a second-order rate constant of 53 M-1min-1. The pKa of the titratable group was pK1=6.6+/-0.6. Inactivation with ethyl acetimidate also shows pseudo-first-order kinetics as well as inactivation with TNM yielding second-order constants of 1.2 M-1min-1 and 2.8 M-1min-1, and pKas of 8.36 and 9.0, respectively. The proposed mechanism involves hydrogen binding of each of the two carboxylic groups to tyrosyl residues; histidine interacts with one of the N-hydrogens of the l-glutamate amino group. We also corroborate the presence of a conservative lysine that has a remarkable ability to coordinate a water molecule that would act as general base.

  1. Aspartic cathepsin D endopeptidase contributes to extracellular digestion in clawed lobsters Homarus americanus and Homarus gammarus.

    Science.gov (United States)

    Rojo, Liliana; Muhlia-Almazan, Adriana; Saborowski, Reinhard; García-Carreño, Fernando

    2010-11-01

    Acid digestive proteinases were studied in the gastric fluids of two species of clawed lobster (Homarus americanus and Homarus gammarus). An active protein was identified in both species as aspartic proteinase by specific inhibition with pepstatin A. It was confirmed as cathepsin D by mass mapping, N-terminal, and full-length cDNA sequencing. Both lobster species transcribed two cathepsin D mRNAs: cathepsin D1 and cathepsin D2. Cathepsin D1 mRNA was detected only in the midgut gland, suggesting its function as a digestive enzyme. Cathepsin D2 mRNA was found in the midgut gland, gonads, and muscle. The deduced amino acid sequence of cathepsin D1 and cathepsin D2 possesses two catalytic DTG active-site motifs, the hallmark of aspartic proteinases. The putatively active cathepsin D1 has a molecular mass of 36.4 kDa and a calculated pI of 4.14 and possesses three potential glycosylation sites. The sequences showed highest similarities with cathepsin D from insects but also with another crustacean cathepsin D. Cathepsin D1 transcripts were quantified during a starvation period using real-time qPCR. In H. americanus, 15 days of starvation did not cause significant changes, but subsequent feeding caused a 2.5-fold increase. In H. gammarus, starvation caused a 40% reduction in cathepsin D1 mRNA, and no effect was observed with subsequent feeding. PMID:20169386

  2. A Single Residue Switch for Mg2+-dependent Inhibition Characterizes Plant Class II Diterpene Cyclases from Primary and Secondary Metabolism*

    Science.gov (United States)

    Mann, Francis M.; Prisic, Sladjana; Davenport, Emily K.; Determan, Mara K.; Coates, Robert M.; Peters, Reuben J.

    2010-01-01

    Class II diterpene cyclases mediate the acid-initiated cycloisomerization reaction that serves as the committed step in biosynthesis of the large class of labdane-related diterpenoid natural products, which includes the important gibberellin plant hormones. Intriguingly, these enzymes are differentially susceptible to inhibition by their Mg2+ cofactor, with those involved in gibberellin biosynthesis being more sensitive to such inhibition than those devoted to secondary metabolism, which presumably limits flux toward the potent gibberellin phytohormones. Such inhibition has been suggested to arise from intrasteric Mg2+ binding to the DXDD motif that cooperatively acts as the catalytic acid, whose affinity must then be modulated in some fashion. While further investigating class II diterpene cyclase catalysis, we discovered a conserved basic residue that seems to act as a counter ion to the DXDD motif, enhancing the ability of aspartic acid to carry out the requisite energetically difficult protonation of a carbon-carbon double bond and also affecting inhibitory Mg2+ binding. Notably, this residue is conserved as a histidine in enzymes involved in gibberellin biosynthesis and as an arginine in those dedicated to secondary metabolism. Interchanging the identity of these residues is sufficient to switch the sensitivity of the parent enzyme to inhibition by Mg2+. These striking findings indicate that this is a single residue switch for Mg2+ inhibition, which not only supports the importance of this biochemical regulatory mechanism in limiting gibberellin biosynthesis, but the importance of its release, presumably to enable higher flux, into secondary metabolism. PMID:20430888

  3. Functional analysis of three amino acid residues of purR re-pressor, Trp147, Gln-218 and Gln-292 in Salmonella typhi-murium

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Hesheng

    2001-01-01

    [1]Zalkin, H., Nygaard, P., Escherichia coli and Salmmella typhimurium Cellular and Molecular Biology, Washington D.C: American Society for Microbiology, 1996, 561-579.[2]Maria, A. S., Choi, K. Y., Lu, F. et al., Mechanism of co-repressor mediated specific DNA binding by the purine repressor, Cell, 1995, 83: 147.[3]Choi, K. Y., Fu, L., Zalkin, H., Mutagenesis of amino acid residues required for binding of co-repressors to the purine repressor, J. Biol. Chem., 1993, 269: 24066.[4]Lu, F., Brennan, R. G., Zalkin, H., Escherichia coli purine repressor: key residues for the allsteic transition between active and inactive conformation and for inter domain signaling, Biochemistry, 1998, 37: 15680.[5]Tang Hua, Qin Junchuan, Wang Aoquan, Regulation of purine biosynthetic genes expression in Salmonella typhimurium (VI)-- Isolation and characterization of superrepressor mutants, Chinese Journal of Genetics (in Chinese), 1998, 25(2): 181.[6]Zhang Hesheng, Wang Aoquan, Regulation of purine biosynthetic genes expression in Salmonella typhimurium (X)--Isola-tion of purR(am) mutant and preliminary study of amino acid substitution, Chinese Journal of Genetics (in Chinese), 2000, 27(2): 170.[7]Davis, R. W., Roth, J. R., Advanced Bacteria Genetics, NY: Cold Spring Harbor Laboratory Press, 1984.[8]Miller, J. H., Experiments in Molecular Genetics, NY: Cold Spring Harbor Laboratory Press, 1972.[9]Sambrook, J., Fritsch, E. F., Maniatis, T., Molecular Cloning, A Laboratory Manual, NY: Cold Spring Harbor laboratory Press, 1989.[10] Katzif, S. D., Lu, C. D., Abdelal, A.T., Salmonela typhimurium purine nucleotide synthesis repressor (purR), GenBank, Ac-cession AF040636, 1998.[11] Weicket,M.J.,Adhya,S., A family of bacteria regulators homologous to Gal and Lac repressors,J.Biol.Chem.,1992,267:15869.

  4. Characterization of amino acid residues within the N-terminal region of Ubc9 that play a role in Ubc9 nuclear localization

    International Nuclear Information System (INIS)

    As the sole E2 enzyme for SUMOylation, Ubc9 is predominantly nuclear. However, the underlying mechanisms of Ubc9 nuclear localization are still not well understood. Here we show that RNAi-depletion of Imp13, an importin known to mediate Ubc9 nuclear import, reduces both Ubc9 nuclear accumulation and global SUMOylation. Furthermore, Ubc9-R13A or Ubc9-H20D mutation previously shown to interrupt the interaction of Ubc9 with nucleus-enriched SUMOs reduces the nuclear enrichment of Ubc9, suggesting that the interaction of Ubc9 with the nuclear SUMOs may enhance Ubc9 nuclear retention. Moreover, Ubc9-R17E mutation, which is known to disrupt the interaction of Ubc9 with both SUMOs and Imp13, causes a greater decrease in Ubc9 nuclear accumulation than Ubc9-R13A or Ubc9-H20D mutation. Lastly, Ubc9-K74A/S89D mutations that perturb the interaction of Ubc9 with nucleus-enriched SUMOylation-consensus motifs has no effect on Ubc9 nuclear localization. Altogether, our results have elucidated that the amino acid residues within the N-terminal region of Ubc9 play a pivotal role in regulation of Ubc9 nuclear localization. - Highlights: • Imp13-mediated nuclear import of Ubc9 is critical for global SUMOylation. • Ubc9 mutations disrupting Ubc9-SUMO interaction decrease Ubc9 nuclear accumulation. • N-terminal amino acid residues of Ubc9 are critical for Ubc9 nuclear enrichment

  5. Characterization of amino acid residues within the N-terminal region of Ubc9 that play a role in Ubc9 nuclear localization

    Energy Technology Data Exchange (ETDEWEB)

    Sekhri, Palak [Department of Biological Sciences, Wayne State University, 5947 Gullen Mall, Detroit, MI 48202 (United States); Tao, Tao [School of Life Sciences, Xiamen University, Xiamen (China); Kaplan, Feige [Department of Human Genetics, McGill University, Montreal (Canada); Zhang, Xiang-Dong, E-mail: xzhang@wayne.edu [Department of Biological Sciences, Wayne State University, 5947 Gullen Mall, Detroit, MI 48202 (United States)

    2015-02-27

    As the sole E2 enzyme for SUMOylation, Ubc9 is predominantly nuclear. However, the underlying mechanisms of Ubc9 nuclear localization are still not well understood. Here we show that RNAi-depletion of Imp13, an importin known to mediate Ubc9 nuclear import, reduces both Ubc9 nuclear accumulation and global SUMOylation. Furthermore, Ubc9-R13A or Ubc9-H20D mutation previously shown to interrupt the interaction of Ubc9 with nucleus-enriched SUMOs reduces the nuclear enrichment of Ubc9, suggesting that the interaction of Ubc9 with the nuclear SUMOs may enhance Ubc9 nuclear retention. Moreover, Ubc9-R17E mutation, which is known to disrupt the interaction of Ubc9 with both SUMOs and Imp13, causes a greater decrease in Ubc9 nuclear accumulation than Ubc9-R13A or Ubc9-H20D mutation. Lastly, Ubc9-K74A/S89D mutations that perturb the interaction of Ubc9 with nucleus-enriched SUMOylation-consensus motifs has no effect on Ubc9 nuclear localization. Altogether, our results have elucidated that the amino acid residues within the N-terminal region of Ubc9 play a pivotal role in regulation of Ubc9 nuclear localization. - Highlights: • Imp13-mediated nuclear import of Ubc9 is critical for global SUMOylation. • Ubc9 mutations disrupting Ubc9-SUMO interaction decrease Ubc9 nuclear accumulation. • N-terminal amino acid residues of Ubc9 are critical for Ubc9 nuclear enrichment.

  6. 湿法炼锌净化渣酸浸的动力学%Acid leaching kinetics of zinc plant purification residue

    Institute of Scientific and Technical Information of China (English)

    李倩; 张宝; 闵小波; 申文前

    2013-01-01

    The leaching processes of zinc plant purification residue in sulfuric acid solution were investigated with respect to the effects of sulfuric acid concentration, reaction temperature, and particle size. A particle size of 75−80 μm was required to leach 99.8%cobalt and 91.97%zinc at 70 °C for 20 min when the sulfuric acid concentration was 100 g/L and the ratio of liquid to solid was 50׃1 (mL/g). The leaching kinetics of zinc plant purification residue in sulfuric acid solution system conformed well to the shrinking core model, and the dissolution rates of cobalt and zinc were found to be controlled by diffusion through a porous product layer. The apparent activation energy values of cobalt and zinc reaction were calculated to be 11.6931 kJ/mol and 6.6894 kJ/mol, respectively, according to the Arrhenius formula equation. The results show that diffusion through the inert particle pores is the leaching kinetics rate-controlling step.%对湿法炼锌净化渣的浸出动力学进行了研究,并探讨了硫酸浓度、反应温度、粒度等对钴、锌浸出率的影响规律。从动力学的角度分析了整个浸出过程,得到优化条件:液固比50:1(mL/g),硫酸浓度100 g/L,反应温度70°C,粒度75~80μm,反应时间20 min。在此优化条件下钴的浸出率为99.8%,锌的浸出率为91.97%。结果表明:在硫酸体系中钴的浸出符合不生成固体产物层的“未反应收缩核”模型。通过 Arrhenius 经验公式求得钴和锌表观反应活化能分别为11.693 kJ/mol和6.6894 kJ/mol,这表明浸出过程受边界层扩散控制。

  7. Specificity for a CCR5 Inhibitor Is Conferred by a Single Amino Acid Residue: ROLE OF ILE198.

    Science.gov (United States)

    Lau, Gloria; Labrecque, Jean; Metz, Markus; Vaz, Roy; Fricker, Simon P

    2015-04-24

    The chemokine receptors CCR5 and CCR2b share 89% amino acid homology. CCR5 is a co-receptor for HIV and CCR5 antagonists have been investigated as inhibitors of HIV infection. We describe the use of two CCR5 antagonists, Schering-C (SCH-C), which is specific for CCR5, and TAK-779, a dual inhibitor of CCR5 and CCR2b, to probe the CCR5 inhibitor binding site using CCR5/CCR2b chimeric receptors. Compound inhibition in the different chimeras was assessed by inhibition of chemokine-induced calcium flux. SCH-C inhibited RANTES (regulated on activation, normal T cell expressed and secreted) (CCL5)-mediated calcium flux on CCR5 with an IC50 of 22.8 nM but was inactive against monocyte chemoattractant protein-1 (CCL2)-mediated calcium flux on CCR2b. However, SCH-C inhibited CCL2-induced calcium flux against a CCR5/CCR2b chimera consisting of transmembrane domains IV-VI of CCR5 with an IC50 of 55 nM. A sequence comparison of CCR5 and CCR2b identified a divergent amino acid sequence located at the junction of transmembrane domain V and second extracellular loop. Transfer of the CCR5 sequence KNFQTLKIV into CCR2b conferred SCH-C inhibition (IC50 of 122 nM) into the predominantly CCR2b chimera. Furthermore, a single substitution, R206I, conferred partial but significant inhibition (IC50 of 1023 nM) by SCH-C. These results show that a limited amino acid sequence is responsible for SCH-C specificity to CCR5, and we propose a model showing the interaction with CCR5 Ile(198).

  8. Key role of cysteine residues and sulfenic acids in thermal- and H2O2-mediated modification of β-lactoglobulin.

    Science.gov (United States)

    Krämer, Anna C; Thulstrup, Peter W; Lund, Marianne N; Davies, Michael J

    2016-08-01

    Oxidation results in protein deterioration in mammals, plants, foodstuffs and pharmaceuticals, via changes in amino acid composition, fragmentation, aggregation, solubility, hydrophobicity, conformation, function and susceptibility to digestion. This study investigated whether and how individual or combined treatment with heat, a commonly encountered factor in industrial processing, and H2O2 alters the structure and composition of the major whey protein β-lactoglobulin. Thermal treatment induced reducible cross-links, with this being enhanced by low H2O2 concentrations, but decreased by high concentrations, where fragmentation was detected. Cross-linking was prevented when the single free Cys121 residue was blocked with iodoacetamide. Low concentrations of H2O2 added before heating depleted thiols, with H2O2 alone, or H2O2 added after heating, having lesser effects. A similar pattern was detected for methionine loss and methionine sulfoxide formation. Tryptophan loss was only detected with high levels of H2O2, and no other amino acid was affected, indicating that sulfur-centered amino acids are critical targets. No protection against aggregation was provided by high concentrations of the radical scavenger 5, 5-dimethyl-1-pyrroline N-oxide (DMPO), consistent with molecular oxidation, rather than radical reactions, being the major process. Sulfenic acid formation was detected by Western blotting and LC-MS/MS peptide mass-mapping of dimedone-treated protein, consistent with these species being significant intermediates in heat-induced cross-linking, especially in the presence of H2O2. Studies using circular dichroism and intrinsic fluorescence indicate that H2O2 increases unfolding during heating. These mechanistic insights provide potential strategies for modulating the extent of modification of proteins exposed to thermal and oxidant treatment. PMID:27430598

  9. Amino acid sequence and posttranslational modifications of human factor VIIa from plasma and transfected baby hamster kidney cells

    International Nuclear Information System (INIS)

    Blood coagulation factor VII is a vitamin K dependent glycoprotein which in its activated form, factor VIIa, participates in the coagulation process by activating factor X and/or factor IX in the presence of Ca2+ and tissue factor. Three types of potential posttranslational modifications exist in the human factor VIIa molecule, namely, 10 γ-carboxylated, N-terminally located glutamic acid residues, 1 β-hydroxylated aspartic acid residue, and 2 N-glycosylated asparagine residues. In the present study, the amino acid sequence and posttranslational modifications of recombinant factor VIIa as purified from the culture medium of a transfected baby hamster kidney cell line have been compared to human plasma factor VIIa. By use of HPLC, amino acid analysis, peptide mapping, and automated Edman degradation, the protein backbone of recombinant factor VIIa was found to be identical with human factor VIIa. Asparagine residues 145 and 322 were found to be fully N-glycosylated in human plasma factor VIIa. In the recombinant factor VIIa, asparagine residue 322 was fully glycosylated whereas asparagine residue 145 was only partially (approximately 66%) glycosylated. Besides minor differences in the sialic acid and fucose contents, the overall carbohydrate compositions were nearly identical in recombinant factor VIIa and human plasma factor VIIa. These results show that factor VIIa as produced in the transfected baby hamster kidney cells is very similar to human plasma factor VIIa and that this cell line thus might represent an alternative source for human factor VIIa

  10. Minimal health impacts but detectable tissue residues after exposure of northern leopard frogs (Lithobates pipiens) to commercial naphthenic acids

    International Nuclear Information System (INIS)

    This presentation reported on a study that examined whether naphthenic acids (NAs) are a toxic component in oil sands process-affected materials (OSPM). The study investigated the toxicity of commercial (Refined Merichem) NAs to native amphibians (northern leopard frogs) exposed to saline conditions comparable to those of reclaimed wetlands on oil sand leases. Gas chromatography-mass spectroscopy analysis showed that the exposure of frogs to NAs solutions for 28 days resulted in proportional NA concentrations in extracts of frog muscle tissue. Biological assays were performed to determine if the increasing exposure to NAs caused a proportional compromise in the health of test animals. The innate immune function, thyroid hormones, and hepatic detoxification enzyme induction did not differ in response to increased tissue concentrations of NAs. The commercial NAs were absorbed and deposited in muscle tissue. It was concluded that NAs play only a small, if any, role in the toxicity of OSPM to frogs.

  11. Minimal health impacts but detectable tissue residues after exposure of northern leopard frogs (Lithobates pipiens) to commercial naphthenic acids

    Energy Technology Data Exchange (ETDEWEB)

    Hersikorn, B. [Saskatchewan Univ., Saskatoon, SK (Canada); Young, R.; Fedorak, P. [Alberta Univ., Edmonton, AB (Canada); Smits, J. [Calgary Univ., AB (Canada)

    2010-07-01

    This presentation reported on a study that examined whether naphthenic acids (NAs) are a toxic component in oil sands process-affected materials (OSPM). The study investigated the toxicity of commercial (Refined Merichem) NAs to native amphibians (northern leopard frogs) exposed to saline conditions comparable to those of reclaimed wetlands on oil sand leases. Gas chromatography-mass spectroscopy analysis showed that the exposure of frogs to NAs solutions for 28 days resulted in proportional NA concentrations in extracts of frog muscle tissue. Biological assays were performed to determine if the increasing exposure to NAs caused a proportional compromise in the health of test animals. The innate immune function, thyroid hormones, and hepatic detoxification enzyme induction did not differ in response to increased tissue concentrations of NAs. The commercial NAs were absorbed and deposited in muscle tissue. It was concluded that NAs play only a small, if any, role in the toxicity of OSPM to frogs.

  12. Expansion of the aspartate [beta]-semialdehyde dehydrogenase family: the first structure of a fungal ortholog

    Energy Technology Data Exchange (ETDEWEB)

    Arachea, B.T.; Liu, X.; Pavlovsky, A.G.; Viola, R.E. (Toledo)

    2010-08-13

    The enzyme aspartate semialdehyde dehydrogenase (ASADH) catalyzes a critical transformation that produces the first branch-point intermediate in an essential microbial amino-acid biosynthetic pathway. The first structure of an ASADH isolated from a fungal species (Candida albicans) has been determined as a complex with its pyridine nucleotide cofactor. This enzyme is a functional dimer, with a similar overall fold and domain organization to the structurally characterized bacterial ASADHs. However, there are differences in the secondary-structural elements and in cofactor binding that are likely to cause the lower catalytic efficiency of this fungal enzyme. Alterations in the dimer interface, through deletion of a helical subdomain and replacement of amino acids that participate in a hydrogen-bonding network, interrupt the intersubunit-communication channels required to support an alternating-site catalytic mechanism. The detailed functional information derived from this new structure will allow an assessment of ASADH as a possible target for antifungal drug development.

  13. The S8 serine, C1A cysteine and A1 aspartic protease families in Arabidopsis.

    Science.gov (United States)

    Beers, Eric P; Jones, Alan M; Dickerman, Allan W

    2004-01-01

    The Arabidopsis thaliana genome has over 550 protease sequences representing all five catalytic types: serine, cysteine, aspartic acid, metallo and threonine (MEROPS peptidase database, http://merops.sanger.ac.uk/), which probably reflect a wide variety of as yet unidentified functions performed by plant proteases. Recent indications that the 26S proteasome, a T1 family-threonine protease, is a regulator of light and hormone responsive signal transduction highlight the potential of proteases to participate in many aspects of plant growth and development. Recent discoveries that proteases are required for stomatal distribution, embryo development and disease resistance point to wider roles for four additional multigene families that include some of the most frequently studied (yet poorly understood) plant proteases: the subtilisin-like, serine proteases (family S8), the papain-like, cysteine proteases (family C1A), the pepsin-like, aspartic proteases (family A1) and the plant matrixin, metalloproteases (family M10A). In this report, 54 subtilisin-like, 30 papain-like and 59 pepsin-like proteases from Arabidopsis, are compared with S8, C1A and A1 proteases known from other plant species at the functional, phylogenetic and gene structure levels. Examples of structural conservation between S8, C1A and A1 genes from rice, barley, tomato and soybean and those from Arabidopsis are noted, indicating that some common, essential plant protease roles were established before the divergence of monocots and eudicots. Numerous examples of tandem duplications of protease genes and evidence for a variety of restricted expression patterns suggest that a high degree of specialization exists among proteases within each family. We propose that comprehensive analysis of the functions of these genes in Arabidopsis will firmly establish serine, cysteine and aspartic proteases as regulators and effectors of a wide range of plant processes.

  14. Lactic Acid Bacteria in Total Mixed Ration Silage Containing Soybean Curd Residue: Their Isolation, Identification and Ability to Inhibit Aerobic Deterioration.

    Science.gov (United States)

    Li, Y; Wang, F; Nishino, N

    2016-04-01

    We investigated the effects of the predominant lactic acid bacteria (LAB) on the fermentation characteristics and aerobic stability of total mixed ration (TMR) silage containing soybean curd residue (SC-TMR silage). The SC-TMR materials were ensiled in laboratory silos for 14 or 56 days. LAB predominant in SC-TMR silage were identified (Exp. 1). Lactobacillus fermentum (L. fermentum) and Streptococcus bovis (S. bovis) were found in the untreated materials, Leuconostoc pseudomesenteroides (L. pseudomesenteroides) in 14-day silage and Lactobacillus plantarum (L. plantarum) in all silages. Pediococcus acidilactici (P. acidilactici), Lactobacillus paracasei (L. paracasei), and Lactobacillus brevis (L. brevis) formed more than 90% of the isolates in 56-day silage. Italian ryegrass and whole crop maize were inoculated with P. acidilactici and L. brevis isolates and the fermentation and aerobic stability determined (Exp. 2). Inoculation with P. acidilactici and L. brevis alone or combined improved the fermentation products in ryegrass silage and markedly enhanced its aerobic stability. In maize silage, P. acidilactici and L. brevis inoculation caused no changes and suppressed deterioration when combined with increases in acetic acid content. The results indicate that P. acidilactici and L. brevis may produce a synergistic effect to inhibit SC-TMR silage deterioration. Further studies are needed to identify the inhibitory substances, which may be useful for developing potential antifungal agents.

  15. Isolation of key amino acid residues at the N-terminal end of the core region Streptococcus downei glucansucrase, GTF-I.

    Science.gov (United States)

    Monchois, V; Vignon, M; Russell, R R

    1999-11-01

    Related streptococcal and Leuconostoc mesenteroides glucansucrases are enzymes of medical and biotechnological interest. Molecular modelling has suggested that the catalytic domain contains a circularly permuted version of the (beta/alpha)8 barrel structure found in the amylase superfamily, and site-directed mutagenesis has identified critical amino acids in this region. In this study, sequential N-terminal truncations of Streptococcus downei GTF-I showed that key amino acids are also present in the first one-third of the core domain. Mutations were introduced at Trp-344, Glu-349 and His-355, residues that are conserved in all glucansucrases and lie within a region which is a target for inhibitory antibodies. W344L, E349L and H355V substitutions were assayed for their effect on mutan synthesis and also on oligosaccharide synthesis with various acceptors. It appeared that Trp-344 and His-355 are involved in the action mechanism of GTF-I; His-355 may also play a role in a binding subsite necessary for oligosaccharide and glucan elongation. PMID:10570812

  16. Supercritical Extraction from Vinification Residues: Fatty Acids, α-Tocopherol, and Phenolic Compounds in the Oil Seeds from Different Varieties of Grape

    Directory of Open Access Journals (Sweden)

    F. Agostini

    2012-01-01

    Full Text Available Supercritical fluid extraction has been widely employed in the extraction of high purity substances. In this study, we used the technology to obtain oil from seeds from a variety of grapes, from vinification residues generated in the Southern region of the state of Rio Grande do Sul, Brazil. This work encompasses three varieties of Vitis vinifera (Moscato Giallo, Merlot, and Cabernet Sauvignon and two of Vitis labrusca (Bordô e Isabel, harvested in 2005 and 2006. We obtained the highest oil content from Bordô (15.40% in 2005 and from Merlot (14.66%, 2006. The biggest concentration of palmitic, stearic, and linoleic acids was observed in Bordô, 2005, and in Bordô, Merlot, and Moscato Giallo, 2006. Bordô showed the highest concentration of oleic acid and α-tocopherol in both seasons too. For the equivalent of procyanidins, we did not notice significant difference among the varieties from the 2005 harvest. In 2006, both varieties Isabel and Cabernet Sauvignon showed a value slightly lower than the other varieties. The concentration of total phenolics was higher in Bordô and Cabernet Sauvignon. The presence of these substances is related to several important pharmacological properties and might be an alternative to conventional processes to obtain these bioactives.

  17. On the activation of bovine plasma factor XIII. Amino acid sequence of the peptide released by thrombin and the terminal residues of the subunit polypeptides.

    Science.gov (United States)

    Nakamura, S; Iwanaga, S; Suzuki, T

    1975-12-01

    A blood coagulation factor, Factor XIII, was highly purified from bovine fresh plasma by a method similar to those used for human plasma Factor XIII. The isolated Factor XIII consisted of two subunit polypeptides, a and b chains, with molecular weights of 79,000 +/- 2,000 and 75,000 +/- 2,000, respectively. In the conversion of Factor XIII to the active enzyme, Factor XIIIa, by bovine thrombin [EC 3.4.21.5], a peptide was liberated. This peptide, designated tentatively as "activation peptide," was isolated by gel-filtration on a Sephadex G-75 column. It contained a total of 37 amino acid residues with a masked N-terminal residue and C-terminal arginine. The whole amino acid sequence of "Activation peptide" was established by the dansyl-Edman method and standard enzymatic techniques, and the masked N-terminal residue was identified as N-acetylserine by using a rat liver acylamino acid-releasing enzyme. This enzyme specifically cleaved the N-acetylserylglutamyl peptide bond serine and the remaining peptide, which was now reactive to 1-dimethylamino-naphthalene-5-sulfonyl chloride. A comparison of the sequences of human and bovine "Activation peptide" revealed five amino acids replacements, Ser-3 to Thr; Gly-5 to Arg; Ile-14 to Val; Thr-18 to Asn, and Pro-26 to Leu. Another difference was the deletion of Leu-34 in the human peptide. Adsorption chromatography on a hydroxylapatite column in the presence of 0.1% sodium dodecyl sulfate was developed as a preparative procedure for the resolution of the two subunit polypeptides, a or a' chain and b chain, constituting the protein molecule of Factor XIII or Factor XIIIa. End group analyses on the isolated pure chains revealed that the structural change of Factor XIII during activation with thrombin occurs only in the N-terminal portion of the a chain, not in the N-terminal end of the b chain or in the C-terminal ends of the a and b chains. From these results, it was concluded that the activation of bovine plasma Factor XIII

  18. Removal of acidic interferences in multi-pesticides residue analysis of fruits using modified magnetic nanoparticles prior to determination via ultra-HPLC-MS/MS

    International Nuclear Information System (INIS)

    The authors describe magnetite (Fe3O4) nanoparticles modified with 3-(N,N-diethylamino) propyltrimethoxysilane (Fe3O4-PSA NPs) for use as a sorbent for dispersive solid phase extraction of pesticide residues. The Fe3O4-PSA NPs were prepared by silanizing Fe3O4 NPs and modifying them with 3-(N,N-diethylamino) propyltrimethoxysilane. Field-emission scanning electron microscopy, FTIR and zeta potential measurements were employed to characterize the modified NPs. They were then used as an adsorbent to remove acidic interferences (such as malic acid and succinic acid), which are major interferences in LC-MS/MS analysis in causing ion suppression in the MS spectra of pesticides. In addition, graphitized carbon black (GCB) was used as an adsorbent to eliminate interferences by pigments. The use of Fe3O4-PSA NPs can replace time-consuming centrifugation as used in the so-called QuEChERS (quick, easy, cheap, effective, rugged and safe) method. This improvement is particularly significant in high-throughput analysis. Following the optimization of the quantities of Fe3O4-PSA NPs and GCB, the method was applied to the determination of 56 pesticides in (spiked) fruits (apple, kiwi, orange and pear) by ultra-HPLC-MS/MS. The analytical ranges typically extend from 1 to 200 ng∙mL−1, and recoveries range from 60.2 to 130 % at different concentrations of all four kinds of fruits. The LOQs for the pesticides are 10 ng∙kg−1, which makes the method a viable tool for pesticide monitoring in fruits. (author)

  19. Effects of N-methyl-D-aspartate Receptor Antagonist MK-801 on Expression of Glial Fibrillary Acidic Protein in the Subventricular Zone of Neonatal Rat%NMDA受体拮抗剂MK-801对新生大鼠室管膜下区胶质纤维酸性蛋白表达的影响

    Institute of Scientific and Technical Information of China (English)

    李晓泉; 陈芳芳; 王伟; 来青伟; 耿德勤; 樊红彬

    2013-01-01

    Aim To investigate the effects of the N-methyl-D-aspartate(NMDA)-receptor antagonist MK801 on the expression of glial fibrillary acidic protein(GFAP) in the subventricular zone(SVZ) of neonatal rat.Methods 40 neonatal SD rats were assigned into two groups,a MK-801 group and a control group.Each group was respectively divided into four time points,including P7 d (postnatal 7 days),P14 d,P21 d and P28 d.Rats in the experiment group were intraperitoneally injected selective non-competitive NMDA receptor antagonist MK-801 (10 mg·kg1),while rats in the control group were intraperitoneally injected saline.Immunohistochemical staining was used to assay the number of GFAP-positive cells in the SVZ.Results ① In the control group,the number of GFAP-positive cells increased at P14 d,and the number of GFAP-positive cells reached maximum at P21 d,positive cells decreased significantly at 28 d.② Compared with the control group,the number of GFAP-positive cells reduced significantly at P 14 d (65.40 ± 6.11) and P21 d (239.60 ± 12.92),and the number of GFAP-positive cells increased significantly [P14 d(79.20 ± 5.26),P21 d(265.20 ± 7.40)](P<0.01),while the number of positive cells without obvious changes at P7 d and P28 d in the MK-801 group.Conclusion NMDA-receptor antagonist MK-801 could reduce the expression of GFAP in the SVZ,and inhibit the neural stem cells proliferation and differentiation.%目的 研究N-甲基-D-天冬氨酸(NMDA)受体拮抗剂MK-801对新生7d大鼠室管膜下区(SVZ)胶质纤维酸性蛋白(GFAP)表达的影响.方法 将40只新生SD大鼠分成对照组和MK-801组,各组按出生后口(P)时间点再随机分成4个亚组:P7d、P14d、P21 d、P28d组.新生大鼠均于生后第3天给药,MK-801组腹腔注射MK-801 10 mg·kg-1;对照组腹腔注射同量生理盐水.通过免疫组化学方法观察大鼠SVZ区GFAP阳性细胞数.结果 ①对照组GFAP阳性细胞数于P14 d开始增加,至P21 d达最大值;但P28 d时阳

  20. Unexpected functional diversity in the fatty acid desaturases of the flour beetle Tribolium castaneum and identification of key residues determining activity.

    Science.gov (United States)

    Haritos, Victoria S; Horne, Irene; Damcevski, Katherine; Glover, Karen; Gibb, Nerida

    2014-08-01

    Desaturases catalyse modifications to fatty acids which are essential to homeostasis and for pheromone and defensive chemical production. All desaturases of the flour beetle Tribolium castaneum were investigated via query of the sequenced genome which yielded 15 putative acyl-Coenzyme A genes. Eleven desaturase mRNA were obtained in full length and functionally expressed in yeast. Phylogenetic analysis separated the desaturases into 4 distinct clades; one clade contained conserved beetle Δ9 desaturases, second clade was Tribolium-specific having diverse activities including Δ5, Δ9 and Δ12 desaturation and the other 2 clades had mixed insect representatives. Three members of this clade contained unusual inserted sequences of ∼20 residues in the C-terminal region and were related to desaturases that all contained similar inserts. Deletion of the entirety of the insert in the flour beetle Δ12 desaturase abolished its activity but this was partially restored by the reintroduction of two histidine residues, suggesting the histidine(s) are required for activity but the full length insert is not. Five new desaturase activities were discovered: Δ9 desaturation of C12:0-C16:0 substrates; two unprecedented Δ5 enzymes acting on C18:0 and C16:0; Δ9 activity exclusively on C16:0 and a further stearate Δ9 desaturase. qPCR analysis ruled out a role in sex pheromone synthesis for the Δ5 and Δ9/C16:0 desaturases. The flour beetle genome has underpinned an examination of all transcribed desaturases in the organism and revealed a diversity of novel and unusual activities, an improved understanding of the evolutionary relationships among insect desaturases and sequence determinants of activity.

  1. Single exposure to cocaine impairs aspartate uptake in the pre-frontal cortex via dopamine D1-receptor dependent mechanisms.

    Science.gov (United States)

    Sathler, Matheus Figueiredo; Stutz, Bernardo; Martins, Robertta Silva; Dos Santos Pereira, Maurício; Pecinalli, Ney Roner; Santos, Luis E; Taveira-da-Silva, Rosilane; Lowe, Jennifer; de Freitas, Isis Grigorio; de Melo Reis, Ricardo Augusto; Manhães, Alex C; Kubrusly, Regina C C

    2016-08-01

    Dopamine and glutamate play critical roles in the reinforcing effects of cocaine. We demonstrated that a single intraperitoneal administration of cocaine induces a significant decrease in [(3)H]-d-aspartate uptake in the pre-frontal cortex (PFC). This decrease is associated with elevated dopamine levels, and requires dopamine D1-receptor signaling (D1R) and adenylyl cyclase activation. The effect was observed within 10min of cocaine administration and lasted for up to 30min. This rapid response is related to D1R-mediated cAMP-mediated activation of PKA and phosphorylation of the excitatory amino acid transporters EAAT1, EAAT2 and EAAT3. We also demonstrated that cocaine exposure increases extracellular d-aspartate, l-glutamate and d-serine in the PFC. Our data suggest that cocaine activates dopamine D1 receptor signaling and PKA pathway to regulate EAATs function and extracellular EAA level in the PFC. PMID:27208619

  2. Selective 'unlabeling' of amino acids in fractionally 13C labeled proteins: An approach for stereospecific NMR assignments of CH3 groups in Val and Leu residues

    Energy Technology Data Exchange (ETDEWEB)

    Atreya, H.S.; Chary, K.V.R. [Tata Institute of Fundamental Research, Department of Chemical Sciences (India)

    2001-03-15

    A novel methodology for stereospecific NMR assignments of methyl (CH{sub 3}) groups of Val and Leu residues in fractionally {sup 13}C-labeled proteins is presented. The approach is based on selective 'unlabeling' of specific amino acids in proteins while fractionally {sup 13}C-labeling the rest. A 2D [{sup 13}C-{sup 1}H] HSQC spectrum recorded on such a sample is devoid of peaks belonging to the 'unlabeled' amino acid residues. Such spectral simplification aids in unambiguous stereospecific assignment of diastereotopic CH{sub 3} groups in Val and Leu residues in large proteins. This methodology has been demonstrated on a 15 kDa calcium binding protein from Entamoeba histolytica (Eh-CaBP)

  3. Residual Momentum

    NARCIS (Netherlands)

    D.C. Blitz (David); J.J. Huij (Joop); M.P.E. Martens (Martin)

    2011-01-01

    textabstractConventional momentum strategies exhibit substantial time-varying exposures to the Fama and French factors. We show that these exposures can be reduced by ranking stocks on residual stock returns instead of total returns. As a consequence, residual momentum earns risk-adjusted profits th

  4. Effects of Denaturation and Amino Acid Modification on Fluorescence Spectrum and Hemagglutinating Activity of Hericium erinaceum Lectin

    Institute of Scientific and Technical Information of China (English)

    Meng GONG; Jie AN; Hong-Zhou LU; Chuan-Fang WU; Yi-Jin LI; Jing-Qiu CHENG; Jin-Ku BAO

    2004-01-01

    A sialic acid-binding lectin (Hericium erinaceum lectin, HEL), isolated from fresh fruiting bodies of Hericium erinaceum, was treated with various temperature and pH to investigate its fluorescencespectra and hemagglutinating activity. It was found that the hemagglutinating activity of HEL was relatively steady below 60℃ and at pH from 6 to 11, and the change of hemagglutinating activity was relative to thechange of hydrophobic areas where tryptophan residues located. In fluorescence quenching study of HEL byacrylamide and K1, it was indicated that nearly all the tryptophan residues of HEL located on the surface ofthe molecule, and most of them were in hydrophobic areas or negatively charged areas. Chemical modifica-tion of HEL proved that there were about twelve tryptophan residues in a HEL molecule and all of them werelocated on the surface or in the shallow groove of the molecule, and eight of them were essential for hemag-glutinating activity; aspartic acid or glutamic acid residues were involved in maintaining the crucial confor-mation of activity center and made great contribution to the hemagglutinating activity of HEL, but they could not touch the sialic acid molecule directly; tyrosine residues also played a role in the hemagglutinating activ-ity of HEL; while arginine, serine, threonine, histidine residues had no effect on the hemagglutinating activity of HEL.

  5. [Determination of the residues of 3-methyl-quinoxaline-2-carboxylic acid and quinoxaline-2-carboxylic acid in animal origin foods by high performance liquid chromatography-tandem mass spectrometry].

    Science.gov (United States)

    Zheng, Ling; Wu, Yujie; Li, Yong; Li, Lihua

    2012-07-01

    A high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/ MS) method was developed for the simultaneous quantitative determination of 3-methyl-quinoxaline-2-carboxylic acid (MQCA) and quinoxaline-2-carboxylic acid (QCA) as the marker residues for carbadox (CBX) and olaquindox (OLA), respectively, in the muscles and livers of porcine and chicken and in the muscles of fish and shrimp. The MQCA and QCA were deproteinated with 5% metaphosphoric acid in 10% methanol followed by liquid-liquid extraction. Further clean-up was performed by solid phase extraction (SPE) through mixed mode anion-exchange columns (Oasis MAX SPE). The separation of the compounds was carried on a Waters Xterra MS C18 column (150 mm x 2.1 mm, 5 microm) by a gradient elution using methanol and 0.2% formic acid as mobile phases. The analytes were detected by tandem mass spectrometry in multiple reaction monitoring (MRM) mode with positive electrospray ionization. The MQCA and QCA were quantified by internal standard method. The linear ranges were 1.0-20.0 microg/L and the correlation coefficients were not less than 0.9996. The average recoveries and relative standard deviations ranged from 62.4%-118% and 1.48%-28.1% respectively at the spiked levels of 0.1, 0.2 and 1.0 microg/kg for the both markers. The limit of quantitation (LOQ) was 0.1 microg/kg. The method is sensitive, accurate and suitable for the determination and confirmation of MQCA and QCA in animal origin foods.

  6. The expression changes of N-methyl-D-aspartic acid receptor in hippocampus of offspring from female rats exposed to aluminum in the pregnancy and lactation%孕哺期铝暴露对仔鼠海马 N-甲基-D-天门冬氨酸受体表达的影响

    Institute of Scientific and Technical Information of China (English)

    靳翠红; 巫生文; 逯晓波; 唐秋实; 刘秋芳; 蔡原

    2011-01-01

    Objective To investigate the effects of aluminum on learning and memory and the expression of N-methyl-D-aspartic acid receptor (NMDAR) of hippocampus in offspring from female rats exposed to Al in the pregnancy or lactation, and to explore the mechanism of toxic effects of Al on central nervous system (CNS) during development. Methods The pregnant Wistar rats were randomly divided into 3 groups based on their body weight, I.e. Control group was exposed to distilled water, low exposure group (0.2 %AlCl3) and high exposure group (0.4 %AlCl3) were exposed orally to AlCl3 in pregnancy and lactation for 6 weeks, 10 rats each group. Aluminum content in blood and brains was determined by atomic absorption spectrophotometry (AAS). Platform experiment was used to detect the abilities of learning and memory. The expression levels of NMDARs were detected by western blot assay. Results The Al content in blood and brains of rats in exposure groups increased significantly with Al dose, as compared with the control group ( P<0.05 ). In platform experiment, the incubation periods of rats in low and high exposure groups were (202.71±81.99 ) and ( 19.67±8.44 )s respectively, which were significantly lower than that [( 300.00±0.00 )s] in control group (P<0.01), but the mistake times of rats in low and high exposure groups were 1.43±0.85 and 2.47±0.99 respectively, which were significantly higher than that (0.00±0.00) in control group (P<0.01). The Al exposure could change the proportion of NMDAR subtypes, the expression levels of NR1 and NR2B in hippocampus of newborn rats in low and high exposure groups were 25.22±0.68, 81.23±15.37 and 24.75±0.71, 56.63 ±7.82, respectively, which were significantly lower than those (31.69±3.44, 107.61±9.05 ) in control group (P<0.05). Conclusion Aluminum exposure in pregnancy and lactation could reduce theabilities of learning and memory in newborn rats, and change the proportion of NMDAR subtypes. The reduced NR1and NR2B

  7. Expression of the Gene Encoding the Tetraploid of Carboxyl-terminal Peptide of β-hCG Containing Thirty-seven Amino Acid Residues in E. coli

    Institute of Scientific and Technical Information of China (English)

    王健; 沈卫英; 周清平; 申庆祥

    2000-01-01

    Objective This study was carried out to investigate the possible enhancement of immunogenicity of the carboxyl-terminal peptide of β-hCG which is made up of 37 amino acid residues (109~145) and contains the specific epitope (antigenic determinant) of hCG.Materials & Methods hCGβ-CTP37 tetraploid cDNA was constructed by linking four hCGβ-CTP37 cDNAs together. The product was then subcloned into the E. coli expression vector pQE60 to construct the expression vector pQE60/ (hCGβ-CTP37)4. Recombinant (hCGβ-CTP37 ) 4 was expressed in E. coil-X-blue.Results Western blot analysis showed that the tetraploid of hCGβ-CTP37 had an apparent molecular weight of 20 kD and had relatively stronger anti-hCG antibody-binding activity compared with the diploid from.Conclusion The tetraploid of hCGβ-CTP37 may be a more potent immunogen for raising anti-hCG vaccines for fertility regulation or suppression of tumor.

  8. Growth performance, carcass traits, physiochemical characteristics and intramuscular fatty acid composition of finishing Japanese black steers fed soybean curd residue and soy sauce cake.

    Science.gov (United States)

    Yasuda, Kaori; Kitagawa, Masayuki; Oishi, Kazato; Hirooka, Hiroyuki; Tamura, Takemi; Kumagai, Hajime

    2016-07-01

    This study was conducted to determine the effects of dietary soybean curd residue (SCR) and soy sauce cake (SSC) on the growth performance, carcass traits and physiochemical and intramuscular fatty acid (FA) characteristics in Japanese Black steers. Ten steers (29.7 ± 0.3 months old, 856.6 ± 24.4 kg body weight) were assigned to either treatment C, fed a conventional concentrate or T, fed the test diet including dried SCR and SSC for 3 months. In growth performance, dry matter (DM) intake and average daily gain, and carcass traits did not differ significantly between the treatments. Color of beef was affected by the dietary treatments and meat samples from T showed higher a(*) value and chroma than those in C. On FA composition, there was no significant difference between the treatments in neutral lipids, whereas in polar lipids, meat samples from T had higher C16:1 (P < 0.05) and tended to have higher C16:0 (P = 0.05) and C18:1 (P = 0.08), but lower C17:0 (P = 0.098), C18:2 (P = 0.06) and C20:4 (P = 0.07) than those from C. The study suggested that SCR and SSC could be used as a substitute for conventional concentrate and would influence meat color and intramuscular FA composition of polar lipids.

  9. Identification of amino acid residues of a designed ankyrin repeat protein potentially involved in intermolecular interactions with CD4: analysis by molecular dynamics simulations.

    Science.gov (United States)

    Nimmanpipug, Piyarat; Khampa, Chalermpon; Lee, Vannajan Sanghiran; Nangola, Sawitree; Tayapiwatana, Chatchai

    2011-11-01

    We applied molecular dynamics simulations to investigate the binding properties of a designed ankyrin repeat protein, the DARPin-CD4 complex. DARPin 23.2 has been reported to disturb the human immunodeficiency virus (HIV) viral entry process by Schweizer et al. The protein docking simulation was analysed by comparing the specific ankyrin binder (DARPin 23.2) to an irrelevant control (2JAB) in forming a composite with CD4. To determine the binding free energy of both ankyrins, the MM/PBSA and MM/GBSA protocols were used. The free energy decomposition of both complexes were analysed to explore the role of certain amino acid residues in complex configuration. Interestingly, the molecular docking analysis of DARPin 23.2 revealed a similar CD4 interaction regarding the gp120 theoretical anchoring motif. In contrast, the binding of control ankyrin to CD4 occurred at a different location. This observation suggests that there is an advantage to the molecular modification of DARPin 23.2, an enhanced affinity for CD4. PMID:21962990

  10. Growth performance, carcass traits, physiochemical characteristics and intramuscular fatty acid composition of finishing Japanese black steers fed soybean curd residue and soy sauce cake.

    Science.gov (United States)

    Yasuda, Kaori; Kitagawa, Masayuki; Oishi, Kazato; Hirooka, Hiroyuki; Tamura, Takemi; Kumagai, Hajime

    2016-07-01

    This study was conducted to determine the effects of dietary soybean curd residue (SCR) and soy sauce cake (SSC) on the growth performance, carcass traits and physiochemical and intramuscular fatty acid (FA) characteristics in Japanese Black steers. Ten steers (29.7 ± 0.3 months old, 856.6 ± 24.4 kg body weight) were assigned to either treatment C, fed a conventional concentrate or T, fed the test diet including dried SCR and SSC for 3 months. In growth performance, dry matter (DM) intake and average daily gain, and carcass traits did not differ significantly between the treatments. Color of beef was affected by the dietary treatments and meat samples from T showed higher a(*) value and chroma than those in C. On FA composition, there was no significant difference between the treatments in neutral lipids, whereas in polar lipids, meat samples from T had higher C16:1 (P < 0.05) and tended to have higher C16:0 (P = 0.05) and C18:1 (P = 0.08), but lower C17:0 (P = 0.098), C18:2 (P = 0.06) and C20:4 (P = 0.07) than those from C. The study suggested that SCR and SSC could be used as a substitute for conventional concentrate and would influence meat color and intramuscular FA composition of polar lipids. PMID:26663641

  11. Analysis of SAT type foot-and-mouth disease virus capsid proteins and the identification of putative amino acid residues affecting virus stability.

    Directory of Open Access Journals (Sweden)

    Francois F Maree

    Full Text Available Foot-and-mouth disease virus (FMDV initiates infection by adhering to integrin receptors on target cells, followed by cell entry and disassembly of the virion through acidification within endosomes. Mild heating of the virions also leads to irreversible dissociation into pentamers, a characteristic linked to reduced vaccine efficacy. In this study, the structural stability of intra- and inter-serotype chimeric SAT2 and SAT3 virus particles to various conditions including low pH, mild temperatures or high ionic strength, was compared. Our results demonstrated that while both the SAT2 and SAT3 infectious capsids displayed different sensitivities in a series of low pH buffers, their stability profiles were comparable at high temperatures or high ionic strength conditions. Recombinant vSAT2 and intra-serotype chimeric viruses were used to map the amino acid differences in the capsid proteins of viruses with disparate low pH stabilities. Four His residues at the inter-pentamer interface were identified that change protonation states at pH 6.0. Of these, the H145 of VP3 appears to be involved in interactions with A141 in VP3 and K63 in VP2, and may be involved in orientating H142 of VP3 for interaction at the inter-pentamer interfaces.

  12. Proteomic investigation of protein profile changes and amino acid residue-level modification in cooked lamb longissimus thoracis et lumborum: The effect of roasting.

    Science.gov (United States)

    Yu, Tzer-Yang; Morton, James D; Clerens, Stefan; Dyer, Jolon M

    2016-09-01

    Protein modifications of meat cooked by typical dry-heat methods (e.g., roasting) are currently not well understood. The present study utilised a shotgun proteomic approach to examine the molecular-level effect of roasting on thin lamb longissimus thoracis et lumborum patties, in terms of changes to both the protein profile and amino acid residue side-chain modifications. Cooking caused aggregation of actin, myosin heavy chains and sarcoplasmic proteins. Longer roasting time resulted in significantly reduced protein extractability as well as protein truncation involving particularly a number of myofibrillar and sarcoplasmic proteins, e.g., 6-phosphofructokinase, beta-enolase, l-lactate dehydrogenase A chain, alpha-actinin-3, actin and possibly myosin heavy chains. Modifications that have potential influence on nutritional properties, including carboxyethyllysine and a potentially glucose-derived N-terminal Amadori compound, were observed in actin and myoglobin after roasting. This study provided new insights into molecular changes resulting from the dry-heat treatment of meat, such as commonly used in food preparation. PMID:27150797

  13. Analysis of SAT type foot-and-mouth disease virus capsid proteins and the identification of putative amino acid residues affecting virus stability.

    Science.gov (United States)

    Maree, Francois F; Blignaut, Belinda; de Beer, Tjaart A P; Rieder, Elizabeth

    2013-01-01

    Foot-and-mouth disease virus (FMDV) initiates infection by adhering to integrin receptors on target cells, followed by cell entry and disassembly of the virion through acidification within endosomes. Mild heating of the virions also leads to irreversible dissociation into pentamers, a characteristic linked to reduced vaccine efficacy. In this study, the structural stability of intra- and inter-serotype chimeric SAT2 and SAT3 virus particles to various conditions including low pH, mild temperatures or high ionic strength, was compared. Our results demonstrated that while both the SAT2 and SAT3 infectious capsids displayed different sensitivities in a series of low pH buffers, their stability profiles were comparable at high temperatures or high ionic strength conditions. Recombinant vSAT2 and intra-serotype chimeric viruses were used to map the amino acid differences in the capsid proteins of viruses with disparate low pH stabilities. Four His residues at the inter-pentamer interface were identified that change protonation states at pH 6.0. Of these, the H145 of VP3 appears to be involved in interactions with A141 in VP3 and K63 in VP2, and may be involved in orientating H142 of VP3 for interaction at the inter-pentamer interfaces. PMID:23717387

  14. Short-chain fatty acids produced in vitro from fibre residues obtained from mixed diets containing different breads and in human faeces during the ingestion of the diets.

    Science.gov (United States)

    Wisker, E; Daniel, M; Rave, G; Feldheim, W

    2000-07-01

    It was studied whether the type of bread (i.e. a low-fibre wheat-rye mixed bread and coarse or fine wholemeal rye bread) either as part of a diet or alone, had an influence on the short-chain fatty acids (SCFA) produced during in vitro fermentation. Fermentation substrates were dietary fibre residues obtained from diets and breads. In addition, it was investigated whether the faecal SCFA pattern in the inoculum donors, who ingested the experimental diets, could be predicted by in vitro fermentation. Yields of SCFA in vitro were 0.51-0.62 g/g fermented polysaccharide. In vitro, the molar ratios of butyrate were higher for the two high-fibre diets containing coarse or fine wholemeal bread than for the low fibre diet containing wheat-rye mixed bread; the difference was significant for the coarse (P bread diet (P = 0.0678). The coarse wholemeal bread alone produced a higher molar ratio of butyrate than the fine wholemeal bread (P bread (P wholemeal bread led to higher faecal butyrate ratios (molar ratios: coarse bread diet 19.6, fine bread diet 17.7) compared with the wheat-rye mixed bread-containing diet (14.9), but the differences between the diets were not significant. For the diets investigated, there were no significant differences between faecal and in vitro SCFA patterns.

  15. Kainate-enhanced release of D-(3H)aspartate from cerebral cortex and striatum: reversal by baclofen and pentobarbital

    Energy Technology Data Exchange (ETDEWEB)

    Potashner, S.J.; Gerard, D.

    1983-06-01

    A study was made of the actions of the excitant neurotoxin, kainic acid, on the uptake and the release of D-(2,3-3H)aspartate (D-ASP) in slices of guinea pig cerebral neocortex and striatum. The slices took up D-ASP, reaching concentrations of the amino acid in the tissue which were 14-23 times that in the medium. Subsequently, electrical stimulation of the slices evoked a Ca2+-dependent release of a portion of the D-ASP. Kainic acid (10(-5)-10(-3) M) produced a dose-dependent inhibition of D-ASP uptake. The electrically evoked release of D-ASP was increased 1.6-2.0 fold by 10(-5) and 10(-4)M kainic acid. The kainate-enlarged release was Ca2+-dependent. Dihydrokainic acid, an analogue of kainic acid with little excitatory or toxic action, did not increase D-ASP release but depressed D-ASP uptake. Attempts were made to block the action of kainic acid with baclofen and pentobarbital, compounds which depress the electrically evoked release of L-glutamate (L-GLU) and L-aspartate (L-ASP). Baclofen (4 X 10(-6)M), an antispastic drug, and pentobarbital (10(-4)M), an anesthetic agent, each inhibited the electrically evoked release of D-ASP and prevented the enhancement of the release above control levels usually produced by 10(-4)M kainic acid. It is proposed that 10(-5) and 10(-4)M kainic acid may enhance the synaptic release of L-GLU and L-ASP from neurons which use these amino acids as transmitters. This action is prevented by baclofen and pentobarbital. In view of the possibility that cell death in Huntington's disease could involve excessive depolarization of striatal and other cells by glutamate, baclofen might be effective in delaying the loss of neurons associated with this condition.

  16. Comparison of a soluble co-formulation of insulin degludec/insulin aspart vs biphasic insulin aspart 30 in type 2 diabetes

    DEFF Research Database (Denmark)

    Niskanen, Leo; Leiter, Lawrence A; Franek, Edward;

    2012-01-01

    Insulin degludec/insulin aspart (IDegAsp) is a soluble co-formulation of insulin degludec (70%) and insulin aspart (IAsp: 30%). Here, we compare the efficacy and safety of IDegAsp, an alternative IDegAsp formulation (AF: containing 45% IAsp), and biphasic IAsp 30 (BIAsp 30)....

  17. Residue-specific description of non-native transient structures in the ensemble of acid-denatured structures of the all-beta protein c-src SH3

    DEFF Research Database (Denmark)

    Rösner, Heike I; Poulsen, Flemming Martin

    2010-01-01

    Secondary chemical shift analysis has been used to characterize the unfolded state of acid-denatured c-src SH3. Even though native c-src SH3 adopts an all-beta fold, we found evidence of transient helicity in regions corresponding to native loops. In particular, residues 40-46, connecting the n......, D. S., et al. (1999) Nat. Struct. Biol. 6, 1016-1024]. This indicated that the transient helicity has no influence or only a weak influence on the actual protein folding reaction. The residual structural propensities were compared to those of other SH3 domains, revealing heterogeneity in the...

  18. Free D-aspartate regulates neuronal dendritic morphology, synaptic plasticity, gray matter volume and brain activity in mammals

    Science.gov (United States)

    Errico, F; Nisticò, R; Di Giorgio, A; Squillace, M; Vitucci, D; Galbusera, A; Piccinin, S; Mango, D; Fazio, L; Middei, S; Trizio, S; Mercuri, N B; Teule, M A; Centonze, D; Gozzi, A; Blasi, G; Bertolino, A; Usiello, A

    2014-01-01

    D-aspartate (D-Asp) is an atypical amino acid, which is especially abundant in the developing mammalian brain, and can bind to and activate N-methyl-D-Aspartate receptors (NMDARs). In line with its pharmacological features, we find that mice chronically treated with D-Asp show enhanced NMDAR-mediated miniature excitatory postsynaptic currents and basal cerebral blood volume in fronto-hippocampal areas. In addition, we show that both chronic administration of D-Asp and deletion of the gene coding for the catabolic enzyme D-aspartate oxidase (DDO) trigger plastic modifications of neuronal cytoarchitecture in the prefrontal cortex and CA1 subfield of the hippocampus and promote a cytochalasin D-sensitive form of synaptic plasticity in adult mouse brains. To translate these findings in humans and consistent with the experiments using Ddo gene targeting in animals, we performed a hierarchical stepwise translational genetic approach. Specifically, we investigated the association of variation in the gene coding for DDO with complex human prefrontal phenotypes. We demonstrate that genetic variation predicting reduced expression of DDO in postmortem human prefrontal cortex is mapped on greater prefrontal gray matter and activity during working memory as measured with MRI. In conclusion our results identify novel NMDAR-dependent effects of D-Asp on plasticity and physiology in rodents, which also map to prefrontal phenotypes in humans. PMID:25072322

  19. Free D-aspartate regulates neuronal dendritic morphology, synaptic plasticity, gray matter volume and brain activity in mammals.

    Science.gov (United States)

    Errico, F; Nisticò, R; Di Giorgio, A; Squillace, M; Vitucci, D; Galbusera, A; Piccinin, S; Mango, D; Fazio, L; Middei, S; Trizio, S; Mercuri, N B; Teule, M A; Centonze, D; Gozzi, A; Blasi, G; Bertolino, A; Usiello, A

    2014-01-01

    D-aspartate (D-Asp) is an atypical amino acid, which is especially abundant in the developing mammalian brain, and can bind to and activate N-methyl-D-Aspartate receptors (NMDARs). In line with its pharmacological features, we find that mice chronically treated with D-Asp show enhanced NMDAR-mediated miniature excitatory postsynaptic currents and basal cerebral blood volume in fronto-hippocampal areas. In addition, we show that both chronic administration of D-Asp and deletion of the gene coding for the catabolic enzyme D-aspartate oxidase (DDO) trigger plastic modifications of neuronal cytoarchitecture in the prefrontal cortex and CA1 subfield of the hippocampus and promote a cytochalasin D-sensitive form of synaptic plasticity in adult mouse brains. To translate these findings in humans and consistent with the experiments using Ddo gene targeting in animals, we performed a hierarchical stepwise translational genetic approach. Specifically, we investigated the association of variation in the gene coding for DDO with complex human prefrontal phenotypes. We demonstrate that genetic variation predicting reduced expression of DDO in postmortem human prefrontal cortex is mapped on greater prefrontal gray matter and activity during working memory as measured with MRI. In conclusion our results identify novel NMDAR-dependent effects of D-Asp on plasticity and physiology in rodents, which also map to prefrontal phenotypes in humans.

  20. Identification of Amino Acid Residues in Fibroblast Growth Factor 14 (FGF14) Required for Structure-Function Interactions with Voltage-gated Sodium Channel Nav1.6.

    Science.gov (United States)

    Ali, Syed R; Singh, Aditya K; Laezza, Fernanda

    2016-05-20

    The voltage-gated Na(+) (Nav) channel provides the basis for electrical excitability in the brain. This channel is regulated by a number of accessory proteins including fibroblast growth factor 14 (FGF14), a member of the intracellular FGF family. In addition to forming homodimers, FGF14 binds directly to the Nav1.6 channel C-tail, regulating channel gating and expression, properties that are required for intrinsic excitability in neurons. Seeking amino acid residues with unique roles at the protein-protein interaction interface (PPI) of FGF14·Nav1.6, we engineered model-guided mutations of FGF14 and validated their impact on the FGF14·Nav1.6 complex and the FGF14:FGF14 dimer formation using a luciferase assay. Divergence was found in the β-9 sheet of FGF14 where an alanine (Ala) mutation of Val-160 impaired binding to Nav1.6 but had no effect on FGF14:FGF14 dimer formation. Additional analysis revealed also a key role of residues Lys-74/Ile-76 at the N-terminal of FGF14 in the FGF14·Nav1.6 complex and FGF14:FGF14 dimer formation. Using whole-cell patch clamp electrophysiology, we demonstrated that either the FGF14(V160A) or the FGF14(K74A/I76A) mutation was sufficient to abolish the FGF14-dependent regulation of peak transient Na(+) currents and the voltage-dependent activation and steady-state inactivation of Nav1.6; but only V160A with a concomitant alanine mutation at Tyr-158 could impede FGF14-dependent modulation of the channel fast inactivation. Intrinsic fluorescence spectroscopy of purified proteins confirmed a stronger binding reduction of FGF14(V160A) to the Nav1.6 C-tail compared with FGF14(K74A/I76A) Altogether these studies indicate that the β-9 sheet and the N terminus of FGF14 are well positioned targets for drug development of PPI-based allosteric modulators of Nav channels. PMID:26994141

  1. 氯胺酮对N-甲基-D-天冬氨酸诱导大鼠脊髓背角星形胶质细胞损伤的作用%Influence of ketamine on astrocyte damage in spinal dorsal horn of rats induced by N-methyl-D-aspartic acid

    Institute of Scientific and Technical Information of China (English)

    李清; 刘菊英; 周青山; 朱涛; 秦成名

    2006-01-01

    组,差异显著[分别为(25.26±6.13)%,(5.66±2.24)%,P<0.01],100μmol/LN-甲基-D-天冬氨酸+1 mmol/L氯胺酮组低于100 μmol/L N-甲基-D-天冬氨酸组,差异显著[分别为(24.41±4.82)%,(25.26±6.13)%,P<0.01].③丙二醛含量和超氧化物歧化酶活性变化:100 μmol/L N-甲基-D-天冬氨酸使星形胶质细胞内丙二醛含量显著升高,而超氧化物歧化酶活性明显降低;1 mmol/L氯胺酮明显降低丙二醛含量,显著增强超氧化物歧化酶活性,该效应在临床镇痛剂量以内有明显量效关系,与N-甲基-D-天冬氨酸组相比差异显著(P<0.01).1 mmol/L氯胺酮组与对照组相比、100μmol/L N-甲基-D-天冬氨酸+0.1 mmol/L氯胺酮组与N-甲基-D-天冬氨酸组相比差异均无显著性.结论:N-甲基-D-天冬氨酸受体过度激活可诱导大鼠脊髓背角星形胶质细胞大量凋亡,适量氯胺酮显著抑制细胞凋亡,其机制可能增强星形胶质细胞Bcl-2蛋白表达,同时抑制自由基的产生和增强超氧化物歧化酶活性.%BACKGROUND: Ketamine is a kind of frequently used general venous anesthesia drug in clinic, and the medication in vein or epidural cavum has analgesic effect. It is N-methyl-D-aspartic acid (NMDA) receptor noncompetitive antagonist, which can inhibit toxic effect of excitatory amino acids.OBJECTIVE: To observe effect of ketamine on apoptosis of dorsal horn astrocytes of spinal cord of rats induced by NMDA receptor over activation and explore its possible mechanism of action.DESIGN: Randomized controlled observation.SETTING: Department of Anesthesiology, Taihe Hospital Affiliated to Yunyang Medical College.MATERIALS: The experiment was conducted at Cell Biology Laboratory,Institute of Basic Medical Sciences, Yunyang Medical College between September 2003 and January 2005. Neonatal Wistar rats of two or three days were provided by Animal Experimental Center of Wuhan University. METHODS: Primary astrocytes in dorsal horn of T11-L6 spinal cord of Wistar rats were purified and

  2. Variation of physicochemical properties of drinking water treatment residuals and Phoslock(®) induced by fulvic acid adsorption: Implication for lake restoration.

    Science.gov (United States)

    Wang, Changhui; Jiang, He-Long; Xu, Huacheng; Yin, Hongbin

    2016-01-01

    The use of phosphorus (P) inactivating agents to reduce internal P loading from sediment for lake restoration has attracted increasing attention. Reasonably, the physicochemical properties of P inactivating agents may vary with the interference of various environmental factors, leading to the change of control effectiveness and risks. In this study, the effect of fulvic acid (FA) adsorption on the properties of two agents, drinking water treatment residuals (DWTRs) and Phoslock®, was investigated. The results showed that after adsorption, there was little change for the main structures of DWTRs and Phoslock®, but the thermostability of Phoslock®, as well as the particle size and settleability of the two agents decreased. The specific surface area and pore volume of DWTRs also decreased, while those of Phoslock® increased. Further analysis indicated that aluminum and iron in DWTRs were stable during FA adsorption, but a substantial increase of lanthanum release from Phoslock® was observed, in particular at first (P < 0.01). Moreover, the P immobilization capability of DWTRs had little change after FA adsorption, while the capability of Phoslock® after FA adsorption decreased in solutions (P < 0.001) and sediments (P < 0.1); interestingly, from the view of engineering application, the performance of Phoslock® was not substantially affected. Overall, each P inactivating agent had its own particular responses of the physicochemical properties to environment factors, and detailed investigations on the applicability of each agent were essential before practical application.

  3. Pantothenic acid biosynthesis in zymomonas

    Energy Technology Data Exchange (ETDEWEB)

    Tao, Luan; Tomb, Jean-Francois; Viitanen, Paul V.

    2014-07-01

    Zymomonas is unable to synthesize pantothenic acid and requires this essential vitamin in growth medium. Zymomonas strains transformed with an operon for expression of 2-dehydropantoate reductase and aspartate 1-decarboxylase were able to grow in medium lacking pantothenic acid. These strains may be used for ethanol production without pantothenic acid supplementation in seed culture and fermentation media.

  4. D-Aspartate drinking solution alleviates pain and cognitive impairment in neuropathic mice.

    Science.gov (United States)

    Palazzo, Enza; Luongo, Livio; Guida, Francesca; Marabese, Ida; Romano, Rosaria; Iannotta, Monica; Rossi, Francesca; D'Aniello, Antimo; Stella, Luigi; Marmo, Federica; Usiello, Alessandro; de Bartolomeis, Andrea; Maione, Sabatino; de Novellis, Vito

    2016-07-01

    D-Aspartate (D-Asp) is a free D-amino acid detected in multiple brain regions and putative precursor of endogenous N-methyl-D-aspartate (NMDA) acting as agonist at NMDA receptors. In this study, we investigated whether D-Asp (20 mM) in drinking solution for 1 month affects pain responses and pain-related emotional, and cognitive behaviour in a model of neuropathic pain induced by the spared nerve injury (SNI) of the sciatic nerve in mice. SNI mice developed mechanical allodynia and motor coordination impairment 30 days after SNI surgery. SNI mice showed cognitive impairment, anxiety and depression-like behaviour, reduced sociability in the three chamber sociability paradigm, increased expression of NR2B subunit of NMDA receptor and Homer 1a in the medial prefrontal cortex (mPFC). The expression of (post synaptic density) PSD-95 and Shank 1was instead unaffected in the mPFC of the SNI mice. Treatment with D-Asp drinking solution, started right after the SNI (day 0), alleviated mechanical allodynia, improved cognition and motor coordination and increased social interaction. D-Asp also restored the levels of extracellular D-Asp, Homer 1a and NR2B subunit of the NMDA receptor to physiological levels and reduced Shank1 and PSD-95 protein levels in the mPFC. Amitriptyline, a tricyclic antidepressant used also to alleviate neuropathic pain in humans, reverted mechanical allodynia and cognitive impairment, and unlike D-Asp, was effective in reducing depression and anxiety-like behaviour in the SNI mice and increased PSD protein level. Altogether these findings demonstrate that D-Asp improves sensorial, motor and cognitive-like symptoms related to chronic pain possibly through glutamate neurotransmission normalization in neuropathic mice. PMID:27115160

  5. D-amino acid peptide residualizing agents bearing N-hydroxysuccinimido- and maleimido-functional groups and their application for trastuzumab radioiodination

    International Nuclear Information System (INIS)

    Introduction: Proteins that undergo receptor-mediated endocytosis are subject to lysosomal degradation, requiring radioiodination methods that minimize loss of radioactivity from tumor cells after this process occurs. To accomplish this, we developed the residualizing radioiodination agent Nϵ-(3-[⁎I]iodobenzoyl)-Lys5-Nα-maleimido-Gly1-D-GEEEK (Mal-D-GEEEK-[⁎I]IB), which enhanced tumor uptake but also increased kidney activity and necessitates generation of sulfhydryl moieties on the protein. The purpose of the current study was to synthesize and evaluate a new D-amino acid based agent that might avoid these potential problems. Methods: Nα-(3-iodobenzoyl)-(5-succinimidyloxycarbonyl)-D-EEEG (NHS-IB-D-EEEG), which contains 3 D-glutamates to provide negative charge and a N-hydroxysuccinimide function to permit conjugation to unmodified proteins, and the corresponding tin precursor were produced by solid phase peptide synthesis and subsequent conjugation with appropriate reagents. Radioiodination of the anti-HER2 antibody trastuzumab using NHS-IB-D-EEEG and Mal-D-GEEEK-IB was compared. Paired-label internalization assays on BT474 breast carcinoma cells and biodistribution studies in athymic mice bearing BT474M1 xenografts were performed to evaluate the two radioiodinated D-peptide trastuzumab conjugates. Results: NHS-[131I]IB-D-EEEG was produced in 53.8% ± 13.4% and conjugated to trastuzumab in 39.5% ± 7.6% yield. Paired-label internalization assays with trastuzumab-NHS-[131I]IB-D-EEEG and trastuzumab-Mal-D-GEEEK-[125I]IB demonstrated similar intracellular trapping for both conjugates at 1 h (131I, 84.4% ± 6.1%; 125I, 88.6% ± 5.2%) through 24 h (131I, 60.7% ± 6.8%; 125I, 64.9% ± 6.9%). In the biodistribution experiment, tumor uptake peaked at 48 h (trastuzumab-NHS-[131I]IB-D-EEEG, 29.8% ± 3.6%ID/g; trastuzumab-Mal-D-GEEEK-[125I]IB, 45.3% ± 5.3%ID/g) and was significantly higher for 125I at all time points. In general, normal tissue levels were lower for

  6. Successful production of recombinant buckwheat cysteine-rich aspartic protease in Escherichia coli

    Directory of Open Access Journals (Sweden)

    MIRA D. MILISAVLJEVIĆ

    2009-06-01

    Full Text Available Herein, the expression of recombinant cysteine-rich atypical buckwheat (Fagopyrum esculentum aspartic protease (FeAPL1 in five Escherichia coli strains differing in their expression capabilities is presented. It was shown that the expression success depended highly on the choice of FeAPL1 fusion partner. His6-FeAPL1 was produced in large quantities as an insoluble protein localized in inclusion bodies. On the other hand, MBP-FeAPL1 was localized in both the cytoplasm and inclusion bodies in BL21 and Rosetta-gami strains. Only purified soluble MBP-FeAPL1 from Rosetta-gami cells showed proteolytic activity at pH 3.0 with BSA as the substrate. The results also indicated that FeAPL1 contained a PRO segment that had to be removed for the enzyme activity to appear. The activity of FeAPL1 produced in the Rosetta-gami strain, which enables disulfide bond formation indicated the importance of the twelve cysteine residues for correct folding and functionality.

  7. Characterization of five putative aspartate aminotransferase genes in the N2-fixing heterocystous cyanobacterium Anabaena sp. strain PCC 7120.

    Science.gov (United States)

    Xu, Xinyi; Gu, Liping; He, Ping; Zhou, Ruanbao

    2015-06-01

    Aspartate and glutamate are two key amino acids used in biosynthesis of many amino acids that play vital role in cellular metabolism. Aspartate aminotransferases (AspATs) are required for channelling nitrogen (N(2)) between Glu and Asp in all life forms. Biochemical and genetic characterization of AspATs have been lacking in N(2)-fixing cyanobacteria. In this report, five putative AspAT genes (alr1039, all2340, alr2765, all4327 and alr4853) were identified in the N(2)-fixing heterocystous cyanobacterium Anabaena sp. PCC 7120. Five recombinant C-terminal hexahistidine-tagged AspATs (AspAT-H(6)) were overexpressed in Escherichia coli and purified to homogeneity. Biochemical analysis demonstrated that these five putative AspATs have authentic AspAT activity in vitro using aspartate as an amino donor. However, the enzymic activities of the five AspATs differed in vitro. Alr4853-H(6) showed the highest AspAT activity, while the enzymic activity for the other four AspATs ranged from 6.5 to 53.7 % activity compared to Alr4853 (100 %). Genetic characterization of the five AspAT genes was also performed by inactivating each individual gene. All of the five AspAT knockout mutants exhibited reduced diazotrophic growth, and alr4853 was further identified to be a Fox gene (requiring fixed N(2) for growth in the presence of oxygen). Four out of five P(aspAT)-gfp transcriptional fusions were constitutively expressed in both diazotrophic and nitrate-dependent growth conditions. Quantitative reverse transcriptase PCR showed that alr4853 expression was increased by 2.3-fold after 24 h of N(2) deprivation. Taken together, these findings add to our understanding of the role of AspATs in N(2)-fixing within heterocystous cyanobacteria.

  8. 有机物料对强酸性茶园土壤的酸度调控研究%Use of Crop Residues to Ameliorate Soil Acidity in A Tea Garden Soil

    Institute of Scientific and Technical Information of China (English)

    王磊; 汪玉; 杨兴伦; 张明; 蒋新

    2013-01-01

    A laboratory incubation study was conducted to investigate the application of crop residues with different C/N ratios and ash alkalinity content.Each component was added at 3 different rates and the potential to ameliorate soil acidity was assessed.Incorporation of crop residues was an effective method to reduce soil exchangeable acidity,Al saturation and increase base saturation,but not necessary for soil pH adjustment.The release of alkalinity from residues and the mineralization of organic nitrogen increased soil pH initially,and then decreased due to nitrifications.Various degrees of nitrification were correlated with the C/N ratios of residues.Crop residues with high C/N ratios (i.e.wheat and rice straw) repressed soil nitrification,which resulted in slight pH decrease,whereas crop residues with low C/N ratios (i.e.rapeseed cake and peanut straw) stimulated soil nitrification,and resulted in a sharp decrease in soil pH.Soil pH at the end of incubation was positively correlated with C/N ratios of residues (y =0.003 43x + 4.14,r =0.977).Further,a significant pH increase occurred as the rates of residues increased for residues high in C/N ratio (P<0.05),but not for residues low in C/N ratio (P>0.05).It is suggested that crop residues high in C/N ratio are preferred to ameliorate soil acidity.A further investigation is needed in the form of long-term field study on amendments variables.%通过室内培养的方式,研究了不同添加剂量下,不同C/N与灰化碱含量的有机物料对酸性茶园土壤的改良能力.试验结果表明:有机物料的添加可以有效地减少土壤交换性酸、铝饱和度,增加土壤交换性碱基,但是在调节土壤pH能力上并非一定有效.初始阶段,“灰化碱”的释放与有机氮的矿化提高了土壤的pH,随后pH由于硝化作用出现不同程度的下降.C/N高的作物秸秆(小麦和水稻秸秆)能够有效地抑制硝化,使pH下降幅度较小;而C/N低的作物秸秆(花生秸秆和

  9. Study on leaching process of lead from acid residue%酸浸渣综合回收浸铅工艺研究

    Institute of Scientific and Technical Information of China (English)

    彭国敏; 俎小凤; 张福元

    2012-01-01

    In allusion to the comprehensive recovery of low-grade lead in acid residue from cyanidation process of golden leaching, salt leaching method was adopted to extract lead in the experimental study. Influences of the factors, such as liquid and solid (L/S) mass ratio, leaching temperature, leaching time, concentration of NaCl, and leaching pH, on leaching ratio of lead were studied through orthogonal experiment. It was found that when L/S mass ratio was 5, leaching tempeture was 333.15 K,mass fraction of NaCl was 30% ,pH =0,and leaching time was 4 h the best average lead leaching rate was 92.05% and relatively standard deviation was 4. 3‰. At room temperature, lead leaching rate also reached 90. 20% and relatively standard deviation was 4.1‰ So salt leaching method is an effective way of lead recovery and gold and silver yield improvement in comprehensive utilization of mines at room temperature.%针对氰化提金工艺酸浸渣中低品位金属铅的综合回收,采用盐浸法对金属铅进行了浸出实验研究,通过正交试验详细考察了浸出液固质量比、浸出温度、氯化钠浓度、浸出pH和浸出时间等因素对浸铅率的影响.结果表明,浸出液固质量比为5、浸出温度为333.15 K、氯化钠质量分数为30%、pH =0、浸出时间为4h的实验条件下,最佳平均浸铅率为92.05%,相对标准偏差RSD=4.3‰;室温下最佳平均浸铅率为90.20%,RSD =4.1‰.因此,酸浸渣常温盐浸提铅是综合利用矿产资源回收铅及提高金、银回收率的有效途径.

  10. Stimulus intensity, cell excitation and the N-methyl-D-aspartate receptor component of sensory responses in the rat spinal cord in vivo.

    Science.gov (United States)

    Chizh, B A; Cumberbatch, M J; Herrero, J F; Stirk, G C; Headley, P M

    1997-09-01

    The importance of receptors for N-methyl-D-aspartate in synaptic plasticity and in triggering long-term pronociceptive changes is explained by their voltage-dependence. This suggests that their contribution to acute nociceptive responses would be determined both by the magnitude of synaptic input and by the level of background excitation. We have now examined the role of N-methyl-D-aspartate receptors in acute nociceptive transmission in the spinal cord. Drugs selectively affecting activity mediated by these receptors were tested on responses of dorsal horn neurons to noxious stimuli of different intensities and at different levels of ongoing spike discharge. The drugs used were the N-methyl-D-aspartate receptor channel blocker ketamine; the competitive antagonists, 3-((R)-2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (D-CPP) and D-2-amino-5-phosphonopentanoic acid (D-AP5), and the positive modulator thyrotropin-releasing hormone. The activity of dorsal horn wide dynamic range neurons was recorded extracellularly in alpha-chloralose-anaesthetized spinalized rats. Their responses to noxious stimuli (pinch, heat and electrical) were monitored in parallel with responses to iontophoretic N-methyl-D-aspartate and (RS)-alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA). Drugs were given i.v. or (D-AP5) iontophoretically. At doses that selectively inhibited responses to exogenous N-methyl-D-aspartate, ketamine (4 or 8, mean 5 mg/kg i.v.) reduced the nociceptive responses of the majority of the cells in deep dorsal horn. Ketamine also reduced wind-up of the responses to repetitive electrical stimulation. Ketamine (4 or 8 mg/kg). D-CPP (2 mg/kg), D-AP5 (iontophoretically) and thyrotrophin-releasing hormone (1 mg/kg) were tested on different magnitude nociceptive responses evoked by alternating intensities of noxious heat or pinch. In percentage terms, the less vigorous responses were affected by all four drugs as much as or more than the more vigorous

  11. 78 FR 20029 - Castor Oil, Polymer With Adipic Acid, Linoleic Acid, Oleic Acid and Ricinoleic Acid; Tolerance...

    Science.gov (United States)

    2013-04-03

    ... AGENCY 40 CFR Part 180 Castor Oil, Polymer With Adipic Acid, Linoleic Acid, Oleic Acid and Ricinoleic...: This regulation establishes an exemption from the requirement of a tolerance for residues of castor oil... residues of castor oil, polymer with adipic acid, linoleic acid, oleic acid and ricinoleic acid on food...

  12. Reversible helix sense inversion in surface-grafted poly(beta-phenethyl-L-aspartate) films

    NARCIS (Netherlands)

    Luijten, Jeroen; Vorenkamp, Eltjo J.; Schouten, Arend J.

    2007-01-01

    The reversible manipulation of the helix screw sense in surface-grafted poly(beta-phenethyl-L-aspartate) (PPELA) films by means of external stimuli was investigated. Ringopening polymerization of beta-phenethyl-L-aspartate N-carboxyanhydride initiated from primary amino-functionalized silicon and qu

  13. Reversible Helix Sense Inversion in Surface-Grafted Poly(β-phenethyl-L-aspartate) Films

    NARCIS (Netherlands)

    Luijten, Jeroen; Vorenkamp, Eltjo J.; Schouten, Arend J.

    2007-01-01

    The reversible manipulation of the helix screw sense in surface-grafted poly(β-phenethyl-L-aspartate) (PPELA) films by means of external stimuli was investigated. Ringopening polymerization of β-phenethyl-L-aspartate N-carboxyanhydride initiated from primary amino-functionalized silicon and quartz s

  14. 石棉尾矿酸浸渣填充改性道路沥青的研究%Research on Road Asphalt Filled and Modified with Acid-leaching Residue of Asbestos Tailings

    Institute of Scientific and Technical Information of China (English)

    孙志明; 郑水林; 文明; 吴照洋

    2009-01-01

    The acid-leaching residue of asbestos tailings is silicon slag of asbestos tailings, one kind of solid waste after acid leaching extraction of magnesium. In this experiment, using acid leaching residue of asbestos tailings after calcination as the filler of asphalt modifier, through the test of penetration, ductility, softening point of modified asphalt, the effects of the adding volume and mixing conditions (temperature, time, etc.) of the acid leaching residue on the performance of road asphalt has been studied. The results showed that the appropriate conditions of modified process is that the adding volume of acid leaching residue 6%, mixing temperature 140℃, and heating mixing time 20rain. In this condition, the performance of modified asphalt material, such as high temperature and low temperature performance, temperature sensitivity, and anti-aging property have been significantly improved.%石棉尾矿酸浸渣是石棉尾矿蛇纹石酸浸提取氧化镁后的硅质粉体材料.本实验以煅烧后的石棉尾矿酸浸渣作为道路沥青填充改性剂,通过测定改性沥青的针入度、延度、软化点等指标,研究了酸浸渣填充量、混合控温以及加热混合时间对道路沥青综合性能的影响.结果表明,石棉尾矿酸浸渣填充改性沥青适宜的填充工艺条件为填充量6%,混合控温140℃,加热混合时间20min;在适宜的填充工艺条件下,改性沥青的高温性能、低温性能、高低温稳定性以及抗老化性均得到显著改善或提高.

  15. Leaching mechanism of zinc powder replacement residue containing gallium and germanium by high pressure acid leaching%锌粉置换镓锗渣高压酸浸的浸出机理

    Institute of Scientific and Technical Information of China (English)

    刘付朋; 刘志宏; 李玉虎; 刘智勇; 李启厚

    2014-01-01

    The high pressure acid leaching of zinc powder replacement residue containing gallium and germanium was carried out. The effects of sulfuric acid concentration, liquid to solid ratio, time, temperature, as well as the kind and concentration of leaching assistant agents on the leaching rates of gallium and germanium were studied, the filterabilities of the leaching residues were also investigated. The results show that increasing sulfuric acid concentration till 156 g/L benefits the leaching of gallium and germanium. Above this point, the leaching rate of germanium will decrease. The increase of leaching time or temperature has little influence on the leaching rates of gallium and germanium, but the filterabilities of leaching residues are improved obviously. Adding cadmium nitrate or sodium nitrate can improve the leaching of gallium and germanium, moreover, adding cadmium nitrate can also improves the filterability of the leaching residue sharply. The sample of zinc powder replacement residues is leached for 3 h under the conditions of sulfuric acid concentration of 156 g/L, cadmium nitrate concentration of 60 g/L as leaching assistant agent, liquid to solid ratio of 8, temperature of 150℃, the leaching rates obtained are over 98% for gallium and over 94% for germanium, respectively. Moreover, the filterability of the leaching residue is 20 times more than that of the residue obtained under normal pressure acid leaching condition.%研究锌粉置换镓锗渣的高压酸浸过程,考察硫酸浓度、液固比、浸出时间、浸出温度、助浸剂种类和添加量对Ga、Ge浸出率以及浸出渣过滤性能的影响。结果表明:增加硫酸浓度有利于Ga、Ge的浸出,但硫酸浓度超过156 g/L后,反而不利于Ge的浸出。浸出时间和温度对Ga、Ge浸出率影响较小,但增加浸出时间或提高反应温度均有利于改善浸出渣的过滤性能。添加硝酸钠或硝酸钙均可促进Ga、Ge

  16. Actinide recovery from pyrochemical residues

    International Nuclear Information System (INIS)

    We demonstrated a new process for recovering plutonium and americium from pyrochemical waste. The method is based on chloride solution anion exchange at low acidity, or acidity that eliminates corrosive HCl fumes. Developmental experiments of the process flow chart concentrated on molten salt extraction (MSE) residues and gave >95% plutonium and >90% americium recovery. The recovered plutonium contained 62- from high-chloride low-acid solution. Americium and other metals are washed from the ion exchange column with lN HNO3-4.8M NaCl. After elution, plutonium is recovered by hydroxide precipitation, and americium is recovered by NaHCO3 precipitation. All filtrates from the process can be discardable as low-level contaminated waste. Production-scale experiments are in progress for MSE residues. Flow charts for actinide recovery from electro-refining and direct oxide reduction residues are presented and discussed

  17. Aspartate Rescues S-phase Arrest Caused by Suppression of Glutamine Utilization in KRas-driven Cancer Cells.

    Science.gov (United States)

    Patel, Deven; Menon, Deepak; Bernfeld, Elyssa; Mroz, Victoria; Kalan, Sampada; Loayza, Diego; Foster, David A

    2016-04-22

    During G1-phase of the cell cycle, normal cells respond first to growth factors that indicate that it is appropriate to divide and then later in G1 to the presence of nutrients that indicate sufficient raw material to generate two daughter cells. Dividing cells rely on the "conditionally essential" amino acid glutamine (Q) as an anaplerotic carbon source for TCA cycle intermediates and as a nitrogen source for nucleotide biosynthesis. We previously reported that while non-transformed cells arrest in the latter portion of G1 upon Q deprivation, mutant KRas-driven cancer cells bypass the G1 checkpoint, and instead, arrest in S-phase. In this study, we report that the arrest of KRas-driven cancer cells in S-phase upon Q deprivation is due to the lack of deoxynucleotides needed for DNA synthesis. The lack of deoxynucleotides causes replicative stress leading to activation of the ataxia telangiectasia and Rad3-related protein (ATR)-mediated DNA damage pathway, which arrests cells in S-phase. The key metabolite generated from Q utilization was aspartate, which is generated from a transaminase reaction whereby Q-derived glutamate is converted to α-ketoglutarate with the concomitant conversion of oxaloacetate to aspartate. Aspartate is a critical metabolite for both purine and pyrimidine nucleotide biosynthesis. This study identifies the molecular basis for the S-phase arrest caused by Q deprivation in KRas-driven cancer cells that arrest in S-phase in response to Q deprivation. Given that arresting cells in S-phase sensitizes cells to apoptotic insult, this study suggests novel therapeutic approaches to KRas-driven cancers.

  18. Intersubunit communication in the dihydroorotase-aspartate transcarbamoylase complex of Aquifex aeolicus: Intersubunit Communication in a Pyrimidine Biosynthetic Complex

    Energy Technology Data Exchange (ETDEWEB)

    Evans, Hedeel Guy [Department of Chemistry, Eastern Michigan University, Ypsilanti Michigan 48197; Department of Biochemistry and Molecular Biology, Wayne State University, School of Medicine, Detroit Michigan 48201; Fernando, Roshini [Department of Chemistry, Eastern Michigan University, Ypsilanti Michigan 48197; Vaishnav, Asmita [Department of Biochemistry and Molecular Biology, Wayne State University, School of Medicine, Detroit Michigan 48201; Kotichukkala, Mahalakshmi [Department of Chemistry, Eastern Michigan University, Ypsilanti Michigan 48197; Heyl, Deborah [Department of Chemistry, Eastern Michigan University, Ypsilanti Michigan 48197; Martin, Philip D. [Department of Chemistry, Wayne State University, Detroit Michigan 48202; Hachem, Fatme [Department of Biochemistry and Molecular Biology, Wayne State University, School of Medicine, Detroit Michigan 48201; Brunzelle, Joseph S. [Life Sciences Collaborative Access Team, Northwestern University, Center for Synchrotron Research, Argonne Illinois 60439; Edwards, Brian F. P. [Department of Biochemistry and Molecular Biology, Wayne State University, School of Medicine, Detroit Michigan 48201; Evans, David R. [Department of Biochemistry and Molecular Biology, Wayne State University, School of Medicine, Detroit Michigan 48201

    2013-12-19

    Aspartate transcarbamoylase and dihydroorotase, enzymes that catalyze the second and third step in de novo pyrimidine biosynthesis, are associated in dodecameric complexes in Aquifex aeolicus and many other organisms. The architecture of the dodecamer is ideally suited to channel the intermediate, carbamoyl aspartate from its site of synthesis on the ATC subunit to the active site of DHO, which catalyzes the next step in the pathway, because both reactions occur within a large, internal solvent-filled cavity. Channeling usually requires that the reactions of the enzymes are coordinated so that the rate of synthesis of the intermediate matches its rate of utilization. The linkage between the ATC and DHO subunits was demonstrated by showing that the binding of the bisubstrate analog, N-phosphonacetyl-L-aspartate to the ATC subunit inhibits the activity of the distal DHO subunit. Structural studies identified a DHO loop, loop A, interdigitating between the ATC domains that would be expected to interfere with domain closure essential for ATC catalysis. Mutation of the DHO residues in loop A that penetrate deeply between the two ATC domains inhibits the ATC activity by interfering with the normal reciprocal linkage between the two enzymes. Moreover, a synthetic peptide that mimics that part of the DHO loop that binds between the two ATC domains was found to be an allosteric or noncompletive ATC inhibitor (Ki = 22 μM). A model is proposed suggesting that loop A is an important component of the functional linkage between the enzymes.

  19. Murine elongation factor 1 alpha (EF-1 alpha) is posttranslationally modified by novel amide-linked ethanolamine-phosphoglycerol moieties. Addition of ethanolamine-phosphoglycerol to specific glutamic acid residues on EF-1 alpha

    International Nuclear Information System (INIS)

    Elongation Factor 1 alpha (EF-1 alpha), an important eukaryotic translation factor, transports charged aminoacyl-tRNA from the cytosol to the ribosomes during poly-peptide synthesis. Metabolic radiolabeling with [3H] ethanolamine shows that, in all cells examined, EF-1 alpha is the major radiolabeled protein. Radiolabeled EF-1 alpha has an apparent Mr = 53,000 and a basic isoelectric point. It is cytosolic and does not contain N-linked oligosaccharides. Trypsin digestion of murine EF-1 alpha generated two major [3H]ethanolamine-labeled peptides. Three peptides were sequenced and were identical to two distinct regions of the human EF-1 alpha protein. Blank sequencing cycles coinciding with glutamic acid in the human cDNA-derived sequence were also found to release [3H]ethanolamine, and compositional analysis of these peptides confirmed the presence of glutamic acid. Dansylation analysis demonstrates that the amine group of the ethanolamine is blocked. These results indicate that EF-1 alpha is posttranslationally modified by the covalent attachment of ethanolamine via an amide bond to at least two specific glutamic acid residues (Glu-301 and Glu-374). The hydroxyl group of the attached ethanolamine was shown by mass spectrometry and compositional analysis, to be further modified by the addition of a phosphoglycerol unit. This novel posttranslational modification may represent an important alteration of EF-1 alpha, comparable to the regulatory effects of posttranslational methylation of EF-1 alpha lysine residues

  20. Amino acid biogeo- and stereochemistry in coastal Chilean sediments

    Science.gov (United States)

    Lomstein, Bente Aa.; Jørgensen, Bo B.; Schubert, Carsten J.; Niggemann, Jutta

    2006-06-01

    The spatial distribution of total hydrolysable amino acids (THAA) and amino acid enantiomers ( D- and L-forms) was investigated in sediments underlying two contrasting Chilean upwelling regions: at ˜23 °S off Antofagasta and at ˜36 °S off Concepción. The contribution of amino acids to total organic carbon (%T AAC: 7-14%) and total nitrogen (%T AAN: 23-38%) in surface sediments decreased with increasing water depth (from 126 to 1350 m) indicating that organic matter becomes increasingly decomposed in surface sediments at greater water depth. Changes in the ratio between the protein amino acid aspartate and its non-protein degradation product β-alanine confirmed this observation. Furthermore, estimates of THAA mineralization showed that sedimentary amino acid reactivity decreased with both increasing water depth as well as progressive degradation status of the organic matter that was incorporated into the sediment. Reactivity of organic matter in the sediment was also assessed using the Degradation Index (DI) developed by [Dauwe, B., Middelburg, J.J., 1998. Amino acids and hexosamines as indicators of organic matter degradation state in North Sea sediments. Limnol. Oceanogr.43, pp. 782-798.]. Off Concepción, DI was successfully applied to examine the degradation status of sedimentary organic matter at different water depths. However, unexpected results were obtained at the Antofagasta stations as DI increased with sediment depth, suggesting more degraded organic matter at the surface than deeper in the cores. The contribution of peptidoglycan amino acids to THAA was estimated from the concentrations of D-aspartate, D-glutamic acid, D-serine, and D-alanine. Peptidoglycan amino acids accounted for >18% of THAA in all investigated samples. In surface sediments peptidoglycan amino acids accounted for a progressively larger fraction of THAA at increasing water depths (up to >26%). Further, the contribution of peptidoglycan amino acids to THAA increased with

  1. The Hydroxyl Side Chain of a Highly Conserved Serine Residue Is Required for Cation Selectivity and Substrate Transport in the Glial Glutamate Transporter GLT-1/SLC1A2.

    Science.gov (United States)

    Simonin, Alexandre; Montalbetti, Nicolas; Gyimesi, Gergely; Pujol-Giménez, Jonai; Hediger, Matthias A

    2015-12-18

    Glutamate transporters maintain synaptic concentration of the excitatory neurotransmitter below neurotoxic levels. Their transport cycle consists of cotransport of glutamate with three sodium ions and one proton, followed by countertransport of potassium. Structural studies proposed that a highly conserved serine located in the binding pocket of the homologous GltPh coordinates L-aspartate as well as the sodium ion Na1. To experimentally validate these findings, we generated and characterized several mutants of the corresponding serine residue, Ser-364, of human glutamate transporter SLC1A2 (solute carrier family 1 member 2), also known as glutamate transporter GLT-1 and excitatory amino acid transporter EAAT2. S364T, S364A, S364C, S364N, and S364D were expressed in HEK cells and Xenopus laevis oocytes to measure radioactive substrate transport and transport currents, respectively. All mutants exhibited similar plasma membrane expression when compared with WT SLC1A2, but substitutions of serine by aspartate or asparagine completely abolished substrate transport. On the other hand, the threonine mutant, which is a more conservative mutation, exhibited similar substrate selectivity, substrate and sodium affinities as WT but a lower selectivity for Na(+) over Li(+). S364A and S364C exhibited drastically reduced affinities for each substrate and enhanced selectivity for L-aspartate over D-aspartate and L-glutamate, and lost their selectivity for Na(+) over Li(+). Furthermore, we extended the analysis of our experimental observations using molecular dynamics simulations. Altogether, our findings confirm a pivotal role of the serine 364, and more precisely its hydroxyl group, in coupling sodium and substrate fluxes.

  2. Bromopyruvate, an active site-directed inactivator of E. coli 2-keto-4-hydroxyglutarate(KHG) aldolase, modifies glutamic acid residue-45

    Energy Technology Data Exchange (ETDEWEB)

    Vlahos, C.J.; Dekker, E.E.

    1987-05-01

    E. coli KHG-aldolase (2-keto-4-hydroxyglutarate in equilibrium pyruvate + glyoxylate), a novel trimeric Class I aldolase, requires one active-site lysine residue (Lys 133)/subunit for Schiff-base formation as well as one arginine residue (Arg 49)/subunit for catalytic activity. The substrate analog, 3-bromopyruvate (BRPY), causes a time- and concentration-dependent loss of KHG-aldolase activity. This inactivation is regarded as active site-directed since: (a) BRPY modification results in complete loss of enzymatic activity; (b) saturation kinetics are exhibited, suggesting that a reversible complex is formed between the aldolase and BRPY prior to the rate-limiting inactivation step; (c) over 90% of the initial aldolase activity is protected by either substrate, pyruvate or KHG; (d) 1.1 mol of /sup 14/C-BRPY is bound/enzyme subunit. Peptide isolation and sequencing show that the incorporated radioactivity is associated with residue Glu-45. Denaturation of the enzyme with guanidine x HCl following treatment with excess /sup 14/C-BRPY allows for the incorporation of carbon-14 at Cys-159 and Cys-180 as well. The presence of pyruvate protects Glu-45 from being esterified but does not prevent the alkylation of the two cysteine residues. These results suggest that Glu-45 is essential for the catalytic activity of E. coli KHG-aldolase, most likely functioning as the active-site amphoteric proton donor/acceptor moiety that is involved in the overall mechanism of the reaction catalyzed by this enzyme.

  3. Alanine and aspartate aminotransferase and glutamine-cycling pathway: Their roles in pathogenesis of metabolic syndrome

    Institute of Scientific and Technical Information of China (English)

    Silvia Sookoian; Carlos J Pirola

    2012-01-01

    Although new research technologies are constantly used to look either for genes or biomarkers in the prediction of metabolic syndrome (MS),the pathogenesis and pathophysiology of this complex disease remains a major challenge.Interestingly,Cheng et al recently investigated possible pathways underlying MS by high-throughput metabolite profiling in two large and well characterized community-based cohorts.The authors explored by liquid chromatography and mass spectrometry the plasma concentrations of 45distinct metabolites and examined their relation to cardiometabolic risk,and observed that metabolic risk factors such as obesity,insulin resistance (IR),high blood pressure,and dyslipidemia were associated with several metabolites,including branched-chain amino acids,other hydrophobic amino acids,tryptophan breakdown products,and nucleotide metabolites.In addition,the authors found a significant association of IR traits with glutamine,glutamate and the glutamineto-glutamate ratio.These data provide new insight into the pathogenesis of MS-associated phenotypes and introduce a crucial role of glutamine-cycling pathway as prominently involved in the development of metabolic risk.We consider that the hypothesis about the role of abnormal glutamate metabolism in the pathogenesis of the MS is certainly challenging and suggests the critical role of the liver in the global metabolic modulation as glutamate metabolism is linked with aminotransferase reactions.We discuss here the critical role of the "liver metabolism" in the pathogenesis of the MS and IR,and postulate that before fatty liver develops,abnormal levels of liver enzymes,such as alanine and aspartate aminotransferases might reflect high levels of hepatic transamination of amino acids in the liver.

  4. Clinical experience with insulin detemir, biphasic insulin aspart and insulin aspart in people with type 2 diabetes: Results from the Kolkata cohort of the A 1 chieve study

    Directory of Open Access Journals (Sweden)

    Anirban Majumder

    2013-01-01

    Full Text Available Background: The A 1 chieve, a multicentric (28 countries, 24-week, non-interventional study evaluated the safety and effectiveness of insulin detemir, biphasic insulin aspart and insulin aspart in people with T2DM (n = 66,726 in routine clinical care across four continents. Materials and Methods: Data was collected at baseline, at 12 weeks and at 24 weeks. This short communication presents the results for patients enrolled from Kolkata, India. Results: A total of 576 patients were enrolled in the study. Four different insulin analogue regimens were used in the study. Patients had started on or were switched to biphasic insulin aspart (n = 417, insulin detemir (n = 70, insulin aspart (n = 55, basal insulin plus insulin aspart (n = 19 and other insulin combinations (n = 15. At baseline, glycaemic control was poor for both insulin naïve (mean HbA 1 c: 8.3% and insulin user (mean HbA 1 c: 8.6% groups. After 24 weeks of treatment, both the groups showed improvement in HbA 1 c (insulin naïve: −1.3%, insulin users: −1.4%. SADRs including major hypoglycaemic events or episodes did not occur in any of the study patients. Conclusion: Starting or switching to insulin analogues was associated with improvement in glycaemic control with a low rate of hypoglycaemia.

  5. Clinical experience with insulin detemir, biphasic insulin aspart and insulin aspart in people with type 2 diabetes: Results from the Hyderabad cohort of the A1chieve study

    Science.gov (United States)

    Santosh, R.; Mehrotra, Ravi; Sastry, N. G.

    2013-01-01

    Background: The A1chieve, a multicentric (28 countries), 24-week, non-interventional study evaluated the safety and effectiveness of insulin detemir, biphasic insulin aspart and insulin aspart in people with T2DM (n = 66,726) in routine clinical care across four continents. Materials and Methods: Data was collected at baseline, at 12 weeks and at 24 weeks. This short communication presents the results for patients enrolled from Hyderabad, India. Results: A total of 1249 patients were enrolled in the study. Four different insulin analogue regimens were used in the study. Patients had started on or were switched to biphasic insulin aspart (n = 893), insulin detemir (n = 158), insulin aspart (n = 124), basal insulin plus insulin aspart (n = 19) and other insulin combinations (n = 54). At baseline glycaemic control was poor for both insulin naïve (mean HbA1c: 9.0%) and insulin user (mean HbA1c: 9.5%) groups. After 24 weeks of treatment, both the groups showed improvement in HbA1c (insulin naïve: −0.9%, insulin users: −1.1%). SADRs including major hypoglycaemic events or episodes did not occur in any of the study patients. Conclusion: Starting or switching to insulin analogues was associated with improvement in glycaemic control with a low rate of hypoglycaemia. PMID:24404501

  6. Site-directed mutagenesis, kinetic and inhibition studies of aspartate ammonia lyase from Bacillus sp YM55-1

    NARCIS (Netherlands)

    Veetil, Vinod Puthan; Raj, Hans; Quax, Wim J.; Janssen, Dick B.; Poelarends, Gerrit J.

    2009-01-01

    Aspartate ammonia lyases (also referred to as aspartases) catalyze the reversible deamination of l-aspartate to yield fumarate and ammonia. In the proposed mechanism for these enzymes, an active site base abstracts a proton from C3 of l-aspartate to form an enzyme-stabilized enediolate intermediate.

  7. Maximization of organic acids production by Aspergillus niger in a bubble column bioreactor for V and Ni recovery enhancement from power plant residual ash in spent-medium bioleaching experiments.

    Science.gov (United States)

    Rasoulnia, P; Mousavi, S M

    2016-09-01

    Spent-medium bioleaching of V and Ni from a power plant residual ash (PPR ash) was conducted using organic acids produced by Aspergillus niger. The production of organic acids in a bubble column bioreactor was optimized through selecting three most influencing factors. Under optimum condition of aeration rate of 762.5(ml/min), sucrose concentration of 101.9(g/l) and inoculum size of 40(ml/l), respectively 17,185, 4539, 1042 and 502(ppm) of oxalic, gluconic, citric and malic acids were produced. Leaching experiments were carried out using biogenic produced organic acids under leaching environment temperature of 60°C and rotary shaking speed of 135rpm, with various pulp densities of 1, 2, 3, 5, 7 and 9(%w/v). The results showed that biogenic produced organic acids leached V much more efficiently than Ni so that even at high pulp density of 9(%w/v), 83% of V was recovered while Ni recovery yield was 30%.

  8. Maximization of organic acids production by Aspergillus niger in a bubble column bioreactor for V and Ni recovery enhancement from power plant residual ash in spent-medium bioleaching experiments.

    Science.gov (United States)

    Rasoulnia, P; Mousavi, S M

    2016-09-01

    Spent-medium bioleaching of V and Ni from a power plant residual ash (PPR ash) was conducted using organic acids produced by Aspergillus niger. The production of organic acids in a bubble column bioreactor was optimized through selecting three most influencing factors. Under optimum condition of aeration rate of 762.5(ml/min), sucrose concentration of 101.9(g/l) and inoculum size of 40(ml/l), respectively 17,185, 4539, 1042 and 502(ppm) of oxalic, gluconic, citric and malic acids were produced. Leaching experiments were carried out using biogenic produced organic acids under leaching environment temperature of 60°C and rotary shaking speed of 135rpm, with various pulp densities of 1, 2, 3, 5, 7 and 9(%w/v). The results showed that biogenic produced organic acids leached V much more efficiently than Ni so that even at high pulp density of 9(%w/v), 83% of V was recovered while Ni recovery yield was 30%. PMID:27295250

  9. Non-equivalence of key positively charged residues of the free fatty acid 2 receptor in the recognition and function of agonist versus antagonist ligands

    DEFF Research Database (Denmark)

    Sergeev, Eugenia; Hojgaard Hansen, Anders; Pandey, Sunil K;

    2016-01-01

    Short chain fatty acids (SCFAs) are produced in the gut by bacterial fermentation of poorly digested carbohydrates. A key mediator of their actions is the G protein-coupled Free Fatty Acid 2 (FFA2) receptor and this has been suggested as a therapeutic target for the treatment of both metabolic...

  10. Solder Flux Residues and Humidity-Related Failures in Electronics: Relative Effects of Weak Organic Acids Used in No-Clean Flux Systems

    DEFF Research Database (Denmark)

    Verdingovas, Vadimas; Jellesen, Morten Stendahl; Ambat, Rajan

    2015-01-01

    This paper presents the results of humidity testing of weak organic acids (WOAs), namely adipic, succinic, glutaric, dl-malic, and palmitic acids, which are commonly used as activators in no-clean solder fluxes. The study was performed under humidity conditions varying from 60% relative humidity ...

  11. The arginine residue within the C-terminal active core of Bombyx mori pheromone biosynthesis-activating neuropeptide (PBAN is essential for receptor binding and activation

    Directory of Open Access Journals (Sweden)

    Takeshi eKawai

    2012-03-01

    Full Text Available In most lepidopteran insects, the biosynthesis of sex pheromones is regulated by pheromone biosynthesis activating neuropeptide (PBAN. Bombyx mori PBAN (BomPBAN consists of 33 amino acid residues and contains a C-terminus FSPRLamide motif as the active core. Among neuropeptides containing the FXPRLamide motif, the arginine (Arg, R residue two positions from the C-terminus is highly conserved across several neuropeptides, which can be designated as RXamide peptides. The purpose of this study was to reveal the role of the Arg residue in the BomPBAN active core. We synthesized a ten-residue peptide corresponding to the C-terminal part of BomPBAN with a series of point mutants at the 2nd position (ie, Arg from the C-terminus, termed the C2 position, and measured their efficacy in stimulating Ca2+ influx in insect cells concomitantly expressing a fluorescent PBAN receptor chimera (PBANR-EGFP and loaded with the fluorescent Ca2+ indicator, Fura Red-AM. PBAN analogs with the C2 position replaced with alanine (Ala, A, aspartic acid (Asp, D, serine (Ser, S or L-2-aminooctanoic acid (Aoc decreased PBAN-like activity. RC2A (SKTRYFSPALamide and RC2D (SKTRYFSPDLamide had the lowest activity and could not inhibit the activity of PBAN C10 (SKTRYFSPRLamide. We also prepared Rhodamine Red-labeled PBAN analogs of the mutants and examined their ability to bind PBANR. In contrast to 100 nM Rhodamine Red-PBAN C10, none of the mutants at the same concentration exhibited PBANR binding. Taken together, our results demonstrate that the C2 Arg residue in BomPBAN is essential for PBANR binding and activation.

  12. Cauliflower mosaic virus produces an aspartic proteinase to cleave its polyproteins.

    Science.gov (United States)

    Torruella, M; Gordon, K; Hohn, T

    1989-10-01

    Cauliflower mosaic virus (CaMV), a plant pararetrovirus, produces polyproteins from its adjacent genes for the coat protein (ORF IV) and for enzymatic functions (ORF V). The N-terminal domain of the latter gene includes a sequence showing homology to the active site of other retroviral and acid proteases. We have now shown that this domain does indeed produce a functional aspartic protease that can process both the polyproteins. Mutations in the putative active site abolished virus infectivity. In transient expression studies in protoplasts, the N-terminal domain of ORF V was able to free active CAT enzyme from a precursor containing an N-terminal fusion of a portion of ORF IV. The junction between the two domains of this artificial polyprotein comprised sequences from the ORF IV product that had previously been shown to include a proteolytic processing site. The protease mutants were not able to free active CAT enzyme from this precursor. Direct analysis of cleavage at the same site in the ORF IV product using proteins expressed in Escherichia coli revealed the expected products. In vitro translation of a synthetic transcript covering ORF V was used to study the autocatalytic cleavage of the ORF product. Pulse-chase experiments showed that the 80 kd initial translation product was processed to yield a N-terminal doublet of polypeptides of 22 and 20 kd apparent mol. wt, which cover the protease domain. The mutants in the active site were not processed. PMID:2684630

  13. Consensus of sample-balanced classifiers for identifying ligand-binding residue by co-evolutionary physicochemical characteristics of amino acids

    KAUST Repository

    Chen, Peng

    2013-01-01

    Protein-ligand binding is an important mechanism for some proteins to perform their functions, and those binding sites are the residues of proteins that physically bind to ligands. So far, the state-of-the-art methods search for similar, known structures of the query and predict the binding sites based on the solved structures. However, such structural information is not commonly available. In this paper, we propose a sequence-based approach to identify protein-ligand binding residues. Due to the highly imbalanced samples between the ligand-binding sites and non ligand-binding sites, we constructed several balanced data sets, for each of which a random forest (RF)-based classifier was trained. The ensemble of these RF classifiers formed a sequence-based protein-ligand binding site predictor. Experimental results on CASP9 targets demonstrated that our method compared favorably with the state-of-the-art. © Springer-Verlag Berlin Heidelberg 2013.

  14. D-Aspartate Modulates Nociceptive-Specific Neuron Activity and Pain Threshold in Inflammatory and Neuropathic Pain Condition in Mice

    Directory of Open Access Journals (Sweden)

    Serena Boccella

    2015-01-01

    Full Text Available D-Aspartate (D-Asp is a free D-amino acid found in the mammalian brain with a temporal-dependent concentration based on the postnatal expression of its metabolizing enzyme D-aspartate oxidase (DDO. D-Asp acts as an agonist on NMDA receptors (NMDARs. Accordingly, high levels of D-Asp in knockout mice for Ddo gene (Ddo−/− or in mice treated with D-Asp increase NMDAR-dependent processes. We have here evaluated in Ddo−/− mice the effect of high levels of free D-Asp on the long-term plastic changes along the nociceptive pathway occurring in chronic and acute pain condition. We found that Ddo−/− mice show an increased evoked activity of the nociceptive specific (NS neurons of the dorsal horn of the spinal cord (L4–L6 and a significant decrease of mechanical and thermal thresholds, as compared to control mice. Moreover, Ddo gene deletion exacerbated the nocifensive responses in the formalin test and slightly reduced pain thresholds in neuropathic mice up to 7 days after chronic constriction injury. These findings suggest that the NMDAR agonist, D-Asp, may play a role in the regulation of NS neuron electrophysiological activity and behavioral responses in physiological and pathological pain conditions.

  15. D-Aspartate Modulates Nociceptive-Specific Neuron Activity and Pain Threshold in Inflammatory and Neuropathic Pain Condition in Mice

    Science.gov (United States)

    Boccella, Serena; Vacca, Valentina; Errico, Francesco; Marinelli, Sara; Squillace, Marta; Di Maio, Anna; Vitucci, Daniela; Palazzo, Enza; De Novellis, Vito; Maione, Sabatino; Pavone, Flaminia; Usiello, Alessandro

    2015-01-01

    D-Aspartate (D-Asp) is a free D-amino acid found in the mammalian brain with a temporal-dependent concentration based on the postnatal expression of its metabolizing enzyme D-aspartate oxidase (DDO). D-Asp acts as an agonist on NMDA receptors (NMDARs). Accordingly, high levels of D-Asp in knockout mice for Ddo gene (Ddo−/−) or in mice treated with D-Asp increase NMDAR-dependent processes. We have here evaluated in Ddo−/− mice the effect of high levels of free D-Asp on the long-term plastic changes along the nociceptive pathway occurring in chronic and acute pain condition. We found that Ddo−/− mice show an increased evoked activity of the nociceptive specific (NS) neurons of the dorsal horn of the spinal cord (L4–L6) and a significant decrease of mechanical and thermal thresholds, as compared to control mice. Moreover, Ddo gene deletion exacerbated the nocifensive responses in the formalin test and slightly reduced pain thresholds in neuropathic mice up to 7 days after chronic constriction injury. These findings suggest that the NMDAR agonist, D-Asp, may play a role in the regulation of NS neuron electrophysiological activity and behavioral responses in physiological and pathological pain conditions. PMID:25629055

  16. THE DISTRIBUTION FUNCTION OF RESIDUE-RESIDUE CONTACTS IN PROTEIN MOLECULES

    Institute of Scientific and Technical Information of China (English)

    Xiang-hong Wang; Jian-hong Ke; Zhen-quan Lin

    2005-01-01

    In protein molecules each residue has a different ability to form contacts. In this paper, we calculated the number of contacts per residue and investigated the distribution of residue-residue contacts from 495 globular protein molecules using Contacts of Structural Units (CSU) software. It was found that the probability P(n) of amino acid residues having n pairs of contacts in all contacts fits Gaussian distribution very well. The distribution function of residue-residue contacts can be expressed as: P(n) = P0 + aexp[-b(n - nc)2]. In our calculation, P0 = -0.06, a = 11.4, b = -0.04 and nc = 9.0. According to distribution function, we found that those hydrophobic (H) residues including Leu, Val, Ile, Met, Phe, Tyr, Cys, and Trp residues have large values of the most probable number of contact nc, and hydrophilic (P) residues including Ala, Gly, Thr,His, Glu, Gln, Asp, Asn, Lys, Ser, Arg, and Pro residues have the small ones. We also compare with Fauchere-Pliska hydrophobicity scale (FPH) and the most probable number of contact nc for 20 amino acid residues, and find that there exists a linear relationship between Fauchere-Pliska hydrophobicity scale (FPH) and the most probable number of contact nc,and it is expressed as: nc = a + b × FPH, here a = 8.87, and b = 1.15. It is important to further explain protein folding and its stability from residue-residue contacts.

  17. 离子色谱法测定硫酸头孢噻利中三氟乙酸残留%Determination of trifluoroacetic acid residue in cefoselis sulfate by ion chromatography

    Institute of Scientific and Technical Information of China (English)

    陈芳; 李润岩; 吴春敏

    2015-01-01

    建立了硫酸头孢噻利中三氟乙酸残留的离子色谱检验方法。实验优化了前处理条件和离子色谱分离条件,结果表明:三氟乙酸在0.1~10.0μg/m L范围内具有良好的线性关系(r=0.9997),精密度(n=6)为1.04%~1.51%,检出限为0.03μg/m L ,加标回收率为97.9%~98.9%。该方法灵敏、快速,高通量,可以为监测该药物中三氟乙酸残留提供科学依据。%A method was conducted for the detection of trifluoroacetic acid residues in cefoselis sulfate by ion chromatography .The operating conditions of pretreatment and the separation of ion chromatography were optimized .The line arrange of trifluoroacetic acid was 0 .1 ~10 .0μg/mL (r=0 .9997) ,T he precision for determining the trifluoroacetic acid pesticides by this method (n=6) varied from 1 .04% to 1 .51% and the limits of detection was 0 .03μg/mL .The spike recoveries ranged 97 .9% ~98 .9% .Proved by this testing ,this method w as sensitive , fast and suitable for the analysis of trifluoroacetic acid residue in cefoselis sulfate .

  18. Three amino acid residues in the envelope of human immunodeficiency virus type 1 CRF07_BC regulate viral neutralization susceptibility to the human monoclonal neutralizing antibody IgG1b12

    Institute of Scientific and Technical Information of China (English)

    Jianhui; Nie; Juan; Zhao; Qingqing; Chen; Weijin; Huang; Youchun; Wang

    2014-01-01

    The CD4 binding site(CD4bs) of envelope glycoprotein(Env) is an important conserved target for anti-human immunodeficiency virus type 1(HIV-1) neutralizing antibodies. Neutralizing monoclonal antibodies IgG1 b12(b12) could recognize conformational epitopes that overlap the CD4 bs of Env. Different virus strains, even derived from the same individual, showed distinct neutralization susceptibility to b12. We examined the key amino acid residues affecting b12 neutralization susceptibility using single genome amplification and pseudovirus neutralization assay. Eleven amino acid residues were identified that affect the sensitivity of Env to b12. Through site-directed mutagenesis, an amino acid substitution at position 182 in the V2 region of Env was confirmed to play a key role in regulating the b12 neutralization susceptibility. The introduction of V182 L to a resistant strain enhanced its sensitivity to b12 more than twofold. Correspondingly, the introduction of L182 V to a sensitive strain reduced its sensitivity to b12 more than tenfold. Amino acid substitution at positions 267 and 346 could both enhance the sensitivity to b12 more than twofold. However, no additive effect was observed when the three site mutageneses were introduced into the same strain, and the sensitivity was equivalent to the single V182 L mutation. CRF07_BC is a major circulating recombinant form of HIV-1 prevalent in China. Our data may provide important information for understanding the molecular mechanism regulating the neutralization susceptibility of CRF07_BC viruses to b12 and may be helpful for a vaccine design targeting the CD4 bs epitopes.

  19. Charge and geometry of residues in the loop 2 β hairpin differentially affect agonist and ethanol sensitivity in glycine receptors.

    Science.gov (United States)

    Perkins, Daya I; Trudell, James R; Asatryan, Liana; Davies, Daryl L; Alkana, Ronald L

    2012-05-01

    Recent studies highlighted the importance of loop 2 of α1 glycine receptors (GlyRs) in the propagation of ligand-binding energy to the channel gate. Mutations that changed polarity at position 52 in the β hairpin of loop 2 significantly affected sensitivity to ethanol. The present study extends the investigation to charged residues. We found that substituting alanine with the negative glutamate at position 52 (A52E) significantly left-shifted the glycine concentration response curve and increased sensitivity to ethanol, whereas the negative aspartate substitution (A52D) significantly right-shifted the glycine EC₅₀ but did not affect ethanol sensitivity. It is noteworthy that the uncharged glutamine at position 52 (A52Q) caused only a small right shift of the glycine EC₅₀ while increasing ethanol sensitivity as much as A52E. In contrast, the shorter uncharged asparagine (A52N) caused the greatest right shift of glycine EC₅₀ and reduced ethanol sensitivity to half of wild type. Collectively, these findings suggest that charge interactions determined by the specific geometry of the amino acid at position 52 (e.g., the 1-Å chain length difference between aspartate and glutamate) play differential roles in receptor sensitivity to agonist and ethanol. We interpret these results in terms of a new homology model of GlyR based on a prokaryotic ion channel and propose that these mutations form salt bridges to residues across the β hairpin (A52E-R59 and A52N-D57). We hypothesize that these electrostatic interactions distort loop 2, thereby changing agonist activation and ethanol modulation. This knowledge will help to define the key physical-chemical parameters that cause the actions of ethanol in GlyRs.

  20. A 193-amino acid fragment of the SARS coronavirus S protein efficiently binds angiotensin-converting enzyme 2.

    Science.gov (United States)

    Wong, Swee Kee; Li, Wenhui; Moore, Michael J; Choe, Hyeryun; Farzan, Michael

    2004-01-30

    The coronavirus spike (S) protein mediates infection of receptor-expressing host cells and is a critical target for antiviral neutralizing antibodies. Angiotensin-converting enzyme 2 (ACE2) is a functional receptor for the coronavirus (severe acute respiratory syndrome (SARS)-CoV) that causes SARS. Here we demonstrate that a 193-amino acid fragment of the S protein (residues 318-510) bound ACE2 more efficiently than did the full S1 domain (residues 12-672). Smaller S protein fragments, expressing residues 327-510 or 318-490, did not detectably bind ACE2. A point mutation at aspartic acid 454 abolished association of the full S1 domain and of the 193-residue fragment with ACE2. The 193-residue fragment blocked S protein-mediated infection with an IC(50) of less than 10 nm, whereas the IC(50) of the S1 domain was approximately 50 nm. These data identify an independently folded receptor-binding domain of the SARS-CoV S protein.

  1. Two Cytoplasmic Acylation Sites and an Adjacent Hydrophobic Residue, but No Other Conserved Amino Acids in the Cytoplasmic Tail of HA from Influenza A Virus Are Crucial for Virus Replication.

    Science.gov (United States)

    Siche, Stefanie; Brett, Katharina; Möller, Lars; Kordyukova, Larisa V; Mintaev, Ramil R; Alexeevski, Andrei V; Veit, Michael

    2015-12-01

    Recruitment of the matrix protein M1 to the assembly site of the influenza virus is thought to be mediated by interactions with the cytoplasmic tail of hemagglutinin (HA). Based on a comprehensive sequence comparison of all sequences present in the database, we analyzed the effect of mutating conserved residues in the cytosol-facing part of the transmembrane region and cytoplasmic tail of HA (A/WSN/33 (H1N1) strain) on virus replication and morphology of virions. Removal of the two cytoplasmic acylation sites and substitution of a neighboring isoleucine by glutamine prevented rescue of infectious virions. In contrast, a conservative exchange of the same isoleucine, non-conservative exchanges of glycine and glutamine, deletion of the acylation site at the end of the transmembrane region and shifting it into the tail did not affect virus morphology and had only subtle effects on virus growth and on the incorporation of M1 and Ribo-Nucleoprotein Particles (RNPs). Thus, assuming that essential amino acids are conserved between HA subtypes we suggest that, besides the two cytoplasmic acylation sites (including adjacent hydrophobic residues), no other amino acids in the cytoplasmic tail of HA are indispensable for virus assembly and budding. PMID:26670246

  2. 杨木废弃物稀酸水解预处理条件的响应面优化%Optimization of Dilute-sulfuric Acid Pretreatment of Poplar Residues by Using Response Surface Design

    Institute of Scientific and Technical Information of China (English)

    房桂干; 刘姗姗; 沈葵忠

    2014-01-01

    The dilute acid hydrolysis was applied to the poplar residues conversion,and the polysaccharides conversion rate was figured out for the assessment of conversion efficiency. Several parameters concerned with the conversion efficiency,such as bio-mass substrate size,dosage of acid,hydrolysis pressure( or temperature)and reaction time were investigated. The response surface experimental design was used to optimize the dilute acid hydrolysis conditions. It was proposed that proper particle sizes were 0. 075 to 0. 096 mm and the optimal conditions for the dilute sulfuric acid hydrolysis were illustrated as the solid to liquid ratio of 1:10,temperature of 158℃,reaction time of 5 min,and the fraction of sulfuric acid of 2. 5%. Under the optimal conditions,the polysaccharides conversion rate was up to 59. 23%. The HPLC analysis of hydrolyzates showed that the main component was xylose(29. 897 g/L)with a content of 64. 8% in total sugar amount,and the second one was glucose(8. 748 g/L)with a content of 18. 9%. Less monosaccharides further degraded in the dilute acid hydrolysis. The SEM observation and XRD analysis of substrate samples before and after the dilute acid hydrolysis showed that the fiber structure of the hydrolysis residue was damaged obviously,and the crystallinity decreased from 57. 45% of the raw material to 47. 37% of the hydrolysis residue. It could be expected that the hydrolysis residue be utilized to make bioethanol by enzymatic hydrolysis and fermentation.%以聚糖类转化率为考核指标,探讨了杨木废弃物稀酸水解预处理物料的适宜颗粒尺寸范围,并用响应面实验设计优化了稀酸水解条件。结果表明,稀酸水解预处理物料的适宜颗粒尺寸为0.075~0.096 mm,稀硫酸水解的优化工艺条件为:固液比1:10,温度158℃,时间5 min,硫酸质量分数2.5%。在此优化条件下,聚糖类转化率为59.23%。稀酸水解液的高效液相色谱分析表明,水

  3. Determination of amino acids in Chinese rice wine by fourier transform near-infrared spectroscopy.

    Science.gov (United States)

    Shen, Fei; Niu, Xiaoying; Yang, Danting; Ying, Yibin; Li, Bobin; Zhu, Geqing; Wu, Jian

    2010-09-01

    Chinese rice wine is abundant in amino acids. The possibility of quantitative detection of 16 free amino acids (aspartic acid, threonine, serine, glutamic acid, proline, glycine, alanine, valine, methionine, isoleucine, leucine, tyrosine, phenylalanine, lysine, histidine, and arginine) in Chinese rice wine by Fourier transform near-infrared (NIR) spectroscopy was investigated for the first time in this study. A total of 98 samples from vintage 2007 rice wines with different aging times were analyzed by NIR spectroscopy in transmission mode. Calibration models were developed using partial least-squares regression (PLSR) with high-performance liquid chromatography (HPLC) by postcolumn derivatization and diode array detection as a reference method. To validate the calibration models, full cross (leave-one-out) validation was employed. The results showed that the calibration statistics were good (rcal>0.94) for all amino acids except proline, histidine, and arginine. The correlation coefficient in cross validation (rcv) was >0.81 for 12 amino acids. The residual predictive deviation (RPD) value obtained was >1.5 in all amino acids except proline and arginine, and it was >2.0 in 6 amino acids. The results obtained in this study indicated that NIR spectroscopy could be used as an easy, rapid, and novel tool to quantitatively predict free amino acids in Chinese rice wine without sophisticated methods. PMID:20707307

  4. Intersubunit communication in the dihydroorotase–aspartate transcarbamoylase complex of Aquifex aeolicus

    OpenAIRE

    Evans, Hedeel Guy; Fernando, Roshini; Vaishnav, Asmita; Kotichukkala, Mahalakshmi; Heyl, Deborah; Hachem, Fatme; Brunzelle, Joseph S.; Edwards, Brian FP; Evans, David R.

    2013-01-01

    Aspartate transcarbamoylase and dihydroorotase, enzymes that catalyze the second and third step in de novo pyrimidine biosynthesis, are associated in dodecameric complexes in Aquifex aeolicus and many other organisms. The architecture of the dodecamer is ideally suited to channel the intermediate, carbamoyl aspartate from its site of synthesis on the ATC subunit to the active site of DHO, which catalyzes the next step in the pathway, because both reactions occur within a large, internal solve...

  5. The Pathway of Product Release from the R State of Aspartate Transcarbamoylase

    OpenAIRE

    Mendes, Kimberly R.; Kantrowitz, Evan R.

    2010-01-01

    The pathway of product release from the R state of aspartate transcarbamoylase has been determined here by solving the crystal structure of Escherichia coli aspartate transcarbamoylase (ATCase) locked in the R-quaternary structure by specific introduction of disulfide bonds. ATCase displays ordered substrate binding and product release, remaining in the R state until substrates are exhausted. The structure reported here represents ATCase in the R state bound to the final product molecule, pho...

  6. Effects of Exogenous Amino Acids on the Contents of Amino Acids in Tobacco Leaves

    Institute of Scientific and Technical Information of China (English)

    WU Xue-ping; LIU Guo-shun; ZHU Kai; PENG Sa; GUO Qiao-yan

    2005-01-01

    The effect of three amino acids on the growth of flue-cured tobacco was studied with water culture. The results showed that the three amino acids improved the growth of flue-cured tobacco and increased the contents of chlorophyll a,chlorophyll b and carotenoid in tobacco. At the same time, the activities of NR (nitrate reductase), INV(invertase) and root growth activity were also significantly enhanced. The exogenous glutamic, aspartate and phenylalanine all increased the amino acid contents of tobacco leaves. Of these three amino acids, glutamic had the greatest effect, the next was aspartate,and phenylalanine had the least effect. These three amino acids all had significantly increased the accumulation of amino acids in the leaves of individual plants of tobacco; and the magnitude of accumulation indicated aspartate > glutamic >phenylalanine.

  7. Selective stimulation of excitatory amino acid receptor subtypes and the survival of cerebellar granule cells in culture: effect of kainic acid

    DEFF Research Database (Denmark)

    Balázs, R; Hack, N; Jørgensen, Ole Steen

    1990-01-01

    Our previous studies showed that the survival of cerebellar granule cells in culture is promoted by treatment with N-methyl-D-aspartate. Here we report on the influence of another glutamate analogue, kainic acid, which, in contrast to N-methyl-D-aspartate, is believed to stimulate transmitter rec...

  8. The C-terminal 18 Amino Acid Region of Dengue Virus NS5 Regulates its Subcellular Localization and Contains a Conserved Arginine Residue Essential for Infectious Virus Production

    Science.gov (United States)

    Ng, Ivan H. W.; Chan, Kitti W. K.; Zhao, Yongqian; Ooi, Eng Eong; Lescar, Julien; Jans, David A.; Forwood, Jade K.

    2016-01-01

    Dengue virus NS5 is the most highly conserved amongst the viral non-structural proteins and is responsible for capping, methylation and replication of the flavivirus RNA genome. Interactions of NS5 with host proteins also modulate host immune responses. Although replication occurs in the cytoplasm, an unusual characteristic of DENV2 NS5 is that it localizes to the nucleus during infection with no clear role in replication or pathogenesis. We examined NS5 of DENV1 and 2, which exhibit the most prominent difference in nuclear localization, employing a combination of functional and structural analyses. Extensive gene swapping between DENV1 and 2 NS5 identified that the C-terminal 18 residues (Cter18) alone was sufficient to direct the protein to the cytoplasm or nucleus, respectively. The low micromolar binding affinity between NS5 Cter18 and the nuclear import receptor importin-alpha (Impα), allowed their molecular complex to be purified, crystallised and visualized at 2.2 Å resolution using x-ray crystallography. Structure-guided mutational analysis of this region in GFP-NS5 clones of DENV1 or 2 and in a DENV2 infectious clone reveal residues important for NS5 subcellular localization. Notably, the trans conformation adopted by Pro-884 allows proper presentation for binding Impα and mutating this proline to Thr, as present in DENV1 NS5, results in mislocalizaion of NS5 to the cytoplasm without compromising virus fitness. In contrast, a single mutation to alanine at NS5 position R888, a residue conserved in all flaviviruses, resulted in a completely non-viable virus, and the R888K mutation led to a severely attenuated phentoype, even though NS5 was located in the nucleus. R888 forms a hydrogen bond with Y838 that is also conserved in all flaviviruses. Our data suggests an evolutionarily conserved function for NS5 Cter18, possibly in RNA interactions that are critical for replication, that is independent of its role in subcellular localization. PMID:27622521

  9. The C-terminal 18 Amino Acid Region of Dengue Virus NS5 Regulates its Subcellular Localization and Contains a Conserved Arginine Residue Essential for Infectious Virus Production.

    Science.gov (United States)

    Tay, Moon Y F; Smith, Kate; Ng, Ivan H W; Chan, Kitti W K; Zhao, Yongqian; Ooi, Eng Eong; Lescar, Julien; Luo, Dahai; Jans, David A; Forwood, Jade K; Vasudevan, Subhash G

    2016-09-01

    Dengue virus NS5 is the most highly conserved amongst the viral non-structural proteins and is responsible for capping, methylation and replication of the flavivirus RNA genome. Interactions of NS5 with host proteins also modulate host immune responses. Although replication occurs in the cytoplasm, an unusual characteristic of DENV2 NS5 is that it localizes to the nucleus during infection with no clear role in replication or pathogenesis. We examined NS5 of DENV1 and 2, which exhibit the most prominent difference in nuclear localization, employing a combination of functional and structural analyses. Extensive gene swapping between DENV1 and 2 NS5 identified that the C-terminal 18 residues (Cter18) alone was sufficient to direct the protein to the cytoplasm or nucleus, respectively. The low micromolar binding affinity between NS5 Cter18 and the nuclear import receptor importin-alpha (Impα), allowed their molecular complex to be purified, crystallised and visualized at 2.2 Å resolution using x-ray crystallography. Structure-guided mutational analysis of this region in GFP-NS5 clones of DENV1 or 2 and in a DENV2 infectious clone reveal residues important for NS5 subcellular localization. Notably, the trans conformation adopted by Pro-884 allows proper presentation for binding Impα and mutating this proline to Thr, as present in DENV1 NS5, results in mislocalizaion of NS5 to the cytoplasm without compromising virus fitness. In contrast, a single mutation to alanine at NS5 position R888, a residue conserved in all flaviviruses, resulted in a completely non-viable virus, and the R888K mutation led to a severely attenuated phentoype, even though NS5 was located in the nucleus. R888 forms a hydrogen bond with Y838 that is also conserved in all flaviviruses. Our data suggests an evolutionarily conserved function for NS5 Cter18, possibly in RNA interactions that are critical for replication, that is independent of its role in subcellular localization. PMID:27622521

  10. Amino acid substitutions of cysteine residues near the amino terminus of Wheat streak mosaic virus HC-Pro abolishes virus transmission by the wheat curl mite

    Science.gov (United States)

    The amino-terminal half of HC-Pro of Wheat streak mosaic virus (WSMV) is required for semi-persistent transmission by the wheat curl mite (Aceria tosichella Keifer). The amino-proximal region of WSMV HC-Pro is cysteine-rich with a zinc finger-like motif. Amino acid substitutions were made in this re...

  11. Clinical experience with insulin detemir, biphasic insulin aspart and insulin aspart in people with type 2 diabetes: Results from the Rajasthan cohort of the A 1 chieve study

    Directory of Open Access Journals (Sweden)

    Akhil Joshi

    2013-01-01

    Full Text Available Background: The A 1 chieve, a multicentric (28 countries, 24-week, non-interventional study evaluated the safety and effectiveness of insulin detemir, biphasic insulin aspart and insulin aspart in people with T2DM (n = 66,726 in routine clinical care across four continents. Materials and Methods: Data was collected at baseline, at 12 weeks and at 24 weeks. This short communication presents the results for patients enrolled from Rajasthan, India. Results: A total of 477 patients were enrolled in the study. Four different insulin analogue regimens were used in the study. Patients had started on or were switched to biphasic insulin aspart (n = 340, insulin detemir (n = 90, insulin aspart (n = 37, basal insulin plus insulin aspart (n = 7 and other insulin combinations (n = 2. At baseline glycaemic control was poor for both insulin naïve (mean HbA 1 c: 8.3% and insulin user (mean HbA 1 c: 8.4% groups. After 24 weeks of treatment, both the groups showed improvement in HbA 1 c (insulin naïve: −0.9%, insulin users: −1.2%. Major hypoglycaemic events decreased from 0.5 events/patient-year to 0.0 events/patient-year in insulin naïve group while no change from baseline (1.3 events/patients-year was observed for insulin users. SADRs were not reported in any of the study patients. Conclusion: Starting or switching to insulin analogues was associated with improvement in glycaemic control with a low rate of hypoglycaemia.

  12. 精氨酸-甘氨酸-天冬氨酸与核糖核酸酶修饰碲化镉量子点探针对黑素瘤A375细胞的靶向研究%Arginine-glycine-aspartic acid-and RNase A-conjugated CdTe quantum dot-based nanoprobes for active targeting of human A375 malignant melanoma cells in vitro

    Institute of Scientific and Technical Information of China (English)

    陈晓罡; 张振; 费烨; 陈向东

    2013-01-01

    Objective To prepare arginine-glycine-aspartic acid (RGD)-and ribonuclease A (RNase A)-conjugated CdTe quantum dot (QD) nanoprobes,and to observe their capability to target human A375 malignant melanoma cells.Methods RNase A-modified CdTe quantum dots (CdTe RQDs) were obtained by using a microwave-based heating method,and then chemically conjugated to the RGD peptide to prepare RGD-CdTe RQD nanoprobes,which were then physically and chemically characterized by transmission electron microscopy,powder crystal diffraction,fluorescence spectrophotometry,and ultraviolet absorption spectrophotometry.A375 cells were cultured in vitro and incubated with various concentrations (20,40,80 nmol/L) of RGD-CdTe RQD nanoprobes for different durations (12,24,36,72 hours).Then,methyl thiazolyl tetrazolium (MTT) assay was conducted to estimate the proliferative activity of A375 cells.To observe the targeting capability of RGD-CdTe RQD nanoprobes,A375 cells were treated with RGD-CdTe RQD nanoprobes at the concentration determined by MTT assay for one hour followed by laser confocal microscopy.Results CdTe RQDs with good dispersion and biocompatibility were obtained by using a microwave-based heating method,and then successfully conjugated to the RGD peptide to form RGD-CdTe RQD nanoprobes.The treatment with RGD-CdTe RQDs of 20 nmol/L for 12 hours exhibited the weakest effect on the proliferative activity of A375 cells,and hence,20 nmol/L was selected for the fluorescence imaging assay.Laser confocal microscopy revealed that RGD-CdTe RQD nanoprobes were able to actively target A375 cells.Conclusion RGD-CdTe RQD nanoprobes with a favorable capability to actively target A375 cells are successfully prepared in this study.%目的 制备精氨酸-甘氨酸-天冬氨酸(RGD)与核糖核酸酶(RNase A)修饰的碲化镉(CdTe)量子点(quantum dot,QDs)的纳米探针,观察其对恶性黑素瘤A375细胞的靶向效果.方法 利用微波加热方法得到核糖核酸酶修

  13. 酱油渣中油脂提取工艺的研究及其脂肪酸成分分析%Fat extraction from soy sauce residues and fatty acids composition analysis

    Institute of Scientific and Technical Information of China (English)

    杨莹莹; 姚舜; 万海清; 余佳; 宋航

    2011-01-01

    Fat extraction from soy sauce residues and the analysis of composition and contents of fatty acids was studied. The extraction conditions were investigated and optimized by single factor and orthogonal experiments. The extracted fatty acids were analyzed by GC-MS. The results showed that the optimum extraction conditions were as follows: the ratio of petroleum ether to 80%vol ethanol 3:2, solid-liquid ratio 1 -1, extraction temperature 65℃, extraction time 2h and extraction 3 times. Under these conditions, the optimal entraction rate was 6.3%. Results of GC/MS indicated that there were 4 kinds of fatty acids in soy sauce oil, and among which the content of palmitic acid was 46.90% and the linoleic acid was 33.26%. This study was expected to provide support for further exploitation of the oil from soy sauce residues.%提取酱油渣中油脂,并对油脂中脂肪酸成分及含量进行了分析.通过单因素和正交试验,研究了油脂的最佳提取条件,采用气相-质谱(GC/MS)联用分析其脂肪酸组成及含量.试验表明:以石油醚和80%vol乙醇为溶剂,料液比1∶7,温度65℃,提取时间2h,3次提取,可以得到油脂的最佳提取率为6.3%.GC/MS分析表明,油脂中含有4种脂肪酸,其中软脂酸含量较高,为46.90%,亚油酸的含量次之,为33.26%.以上研究为酱油渣中油脂的进一步开发利用提供了依据.

  14. H9N2 influenza virus acquires intravenous pathogenicity on the introduction of a pair of di-basic amino acid residues at the cleavage site of the hemagglutinin and consecutive passages in chickens

    Directory of Open Access Journals (Sweden)

    Sakoda Yoshihiro

    2011-02-01

    Full Text Available Abstract Background Outbreaks of avian influenza (AI caused by infection with low pathogenic H9N2 viruses have occurred in poultry, resulting in serious economic losses in Asia and the Middle East. It has been difficult to eradicate the H9N2 virus because of its low pathogenicity, frequently causing in apparent infection. It is important for the control of AI to assess whether the H9N2 virus acquires pathogenicity as H5 and H7 viruses. In the present study, we investigated whether a non-pathogenic H9N2 virus, A/chicken/Yokohama/aq-55/2001 (Y55 (H9N2, acquires pathogenicity in chickens when a pair of di-basic amino acid residues is introduced at the cleavage site of its HA molecule. Results rgY55sub (H9N2, which had four basic amino acid residues at the HA cleavage site, replicated in MDCK cells in the absence of trypsin after six consecutive passages in the air sacs of chicks, and acquired intravenous pathogenicity to chicken after four additional passages. More than 75% of chickens inoculated intravenously with the passaged virus, rgY55sub-P10 (H9N2, died, indicating that it is pathogenic comparable to that of highly pathogenic avian influenza viruses (HPAIVs defined by World Organization for Animal Health (OIE. The chickens inoculated with the virus via the intranasal route, however, s