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Sample records for amino acid transport systems

  1. Identification of a novel system L amino acid transporter structurally distinct from heterodimeric amino acid transporters.

    Science.gov (United States)

    Babu, Ellappan; Kanai, Yoshikatsu; Chairoungdua, Arthit; Kim, Do Kyung; Iribe, Yuji; Tangtrongsup, Sahatchai; Jutabha, Promsuk; Li, Yuewei; Ahmed, Nesar; Sakamoto, Shinichi; Anzai, Naohiko; Nagamori, Seishi; Endou, Hitoshi

    2003-10-31

    A cDNA that encodes a novel Na+-independent neutral amino acid transporter was isolated from FLC4 human hepatocarcinoma cells by expression cloning. When expressed in Xenopus oocytes, the encoded protein designated LAT3 (L-type amino acid transporter 3) transported neutral amino acids such as l-leucine, l-isoleucine, l-valine, and l-phenylalanine. The LAT3-mediated transport was Na+-independent and inhibited by 2-aminobicyclo[2.2.1]heptane-2-carboxylic acid, consistent with the properties of system L. Distinct from already known system L transporters LAT1 and LAT2, which form heterodimeric complex with 4F2 heavy chain, LAT3 was functional by itself in Xenopus oocytes. The deduced amino acid sequence of LAT3 was identical to the gene product of POV1 reported as a prostate cancer-up-regulated gene whose function was not determined, whereas it did not exhibit significant similarity to already identified transporters. The Eadie-Hofstee plots of LAT3-mediated transport were curvilinear, whereas the low affinity component is predominant at physiological plasma amino acid concentration. In addition to amino acid substrates, LAT3 recognized amino acid alcohols. The transport of l-leucine was electroneutral and mediated by a facilitated diffusion. In contrast, l-leucinol, l-valinol, and l-phenylalaninol, which have a net positive charge induced inward currents under voltage clamp, suggesting these compounds are transported by LAT3. LAT3-mediated transport was inhibited by the pretreatment with N-ethylmaleimide, consistent with the property of system L2 originally characterized in hepatocyte primary culture. Based on the substrate selectivity, affinity, and N-ethylmaleimide sensitivity, LAT3 is proposed to be a transporter subserving system L2. LAT3 should denote a new family of organic solute transporters. PMID:12930836

  2. [Inherited amino acid transport disorders].

    Science.gov (United States)

    Igarashi, Y; Tada, K

    1992-07-01

    Disorders due to inherited amino acids transport defect are reviewed. The disorders were categorized into three types of transport defects, namely, brush-border membrane of epithelial cells of small intestine and kidney tubules (Hartnup disease, blue diaper syndrome, cystinuria, iminoglycinuria and lysine malabsorption syndrome), basolateral membrane (lysinuric protein intolerance) and membrane of intracellular organelles (cystinosis and hyperornitinemia-hyperammonemia-homocitrullinuria syndrome). Pathogenesis, clinical feature, laboratory findings, diagnosis, genetics and treatment of these disorders are described, briefly. There is not much data for the transport systems themselves, so that further investigation in molecular and gene levels for transport systems is necessary to clarify the characteristics of the transport and heterogeneity of phenotypes in inherited amino acids transport disorders. PMID:1404888

  3. Effect of Cholesterol on the Branched-Chain Amino Acid Transport System of Streptococcus cremoris

    NARCIS (Netherlands)

    Zheng, Tan; Driessen, Arnold J.M.; Konings, Wilhelmus

    1988-01-01

    The effect of cholesterol on the activity of the branched-chain amino acid transport system of Streptococcus cremoris was studied in membrane vesicles of S. cremoris fused with liposomes made of egg yolk phosphatidylcholine, soybean phosphatidylethanolamine, and various amounts of cholesterol. Chole

  4. Transport of methylmercury—cysteine conjugate by system L—tpye amino acid transporters and its transportermediated toxicity

    Institute of Scientific and Technical Information of China (English)

    KanaY; KimDK

    2002-01-01

    Methylmercury(MeHg) is widely known for its potent neurotoxicity and the causal substance of Minamata disease.Since the conjugates of MeHg with thiol compounds are easily formed in vivo,the metabolism and transport of glutathione,cysteine and their derivatives are important determinants of tissue distribution and elimination of MeHg.It has been proposed that the amino acid transport system L,which transports large neutral amino acids,is one of the major routes for MeHg mobilization.We have identified two isoforms of system L amino acid transporters:L-type amino acid transkporter-1(LAT1) and LAT2 and found that they transport MeHg as a cysteine-conjugate (MeHg-Cys).We have further found that a classical system L inhibitor BCH[2-aminobicyclo-(2,2,1)-heptane-2-carboxylic acid] rescued T24 human bladder carcinoma cells expressing LAT1 form the toxicity of MeHg-Cysl.We concluded that the cytotoxicity of MeHg is mediated by system L transporters.The fact that BCH reduced the toxicity of MeHg-Cys suggests that the high-affinity inhibitors of system L transporters could be a new rationable to avoid MeHg-toxicity.

  5. Quinone-amino acid conjugates targeting Leishmania amino acid transporters.

    Science.gov (United States)

    Prati, Federica; Goldman-Pinkovich, Adele; Lizzi, Federica; Belluti, Federica; Koren, Roni; Zilberstein, Dan; Bolognesi, Maria Laura

    2014-01-01

    The aim of the present study was to investigate the feasibility of targeting Leishmania transporters via appropriately designed chemical probes. Leishmania donovani, the parasite that causes visceral leishmaniasis, is auxotrophic for arginine and lysine and has specific transporters (LdAAP3 and LdAAP7) to import these nutrients. Probes 1-15 were originated by conjugating cytotoxic quinone fragments (II and III) with amino acids (i.e. arginine and lysine) by means of an amide linkage. The toxicity of the synthesized conjugates against Leishmania extracellular (promastigotes) and intracellular (amastigotes) forms was investigated, as well their inhibition of the relevant amino acid transporters. We observed that some conjugates indeed displayed toxicity against the parasites; in particular, 7 was identified as the most potent derivative (at concentrations of 1 µg/mL and 2.5 µg/mL residual cell viability was reduced to 15% and 48% in promastigotes and amastigotes, respectively). Notably, 6, while retaining the cytotoxic activity of quinone II, displayed no toxicity against mammalian THP1 cells. Transport assays indicated that the novel conjugates inhibited transport activity of lysine, arginine and proline transporters. Furthermore, our analyses suggested that the toxic conjugates might be translocated by the transporters into the cells. The non-toxic probes that inhibited transport competed with the natural substrates for binding to the transporters without being translocated. Thus, it is likely that 6, by exploiting amino acid transporters, can selectively deliver its toxic effects to Leishmania cells. This work provides the first evidence that amino acid transporters of the human pathogen Leishmania might be modulated by small molecules, and warrants their further investigation from drug discovery and chemical biology perspectives. PMID:25254495

  6. Quinone-amino acid conjugates targeting Leishmania amino acid transporters.

    Directory of Open Access Journals (Sweden)

    Federica Prati

    Full Text Available The aim of the present study was to investigate the feasibility of targeting Leishmania transporters via appropriately designed chemical probes. Leishmania donovani, the parasite that causes visceral leishmaniasis, is auxotrophic for arginine and lysine and has specific transporters (LdAAP3 and LdAAP7 to import these nutrients. Probes 1-15 were originated by conjugating cytotoxic quinone fragments (II and III with amino acids (i.e. arginine and lysine by means of an amide linkage. The toxicity of the synthesized conjugates against Leishmania extracellular (promastigotes and intracellular (amastigotes forms was investigated, as well their inhibition of the relevant amino acid transporters. We observed that some conjugates indeed displayed toxicity against the parasites; in particular, 7 was identified as the most potent derivative (at concentrations of 1 µg/mL and 2.5 µg/mL residual cell viability was reduced to 15% and 48% in promastigotes and amastigotes, respectively. Notably, 6, while retaining the cytotoxic activity of quinone II, displayed no toxicity against mammalian THP1 cells. Transport assays indicated that the novel conjugates inhibited transport activity of lysine, arginine and proline transporters. Furthermore, our analyses suggested that the toxic conjugates might be translocated by the transporters into the cells. The non-toxic probes that inhibited transport competed with the natural substrates for binding to the transporters without being translocated. Thus, it is likely that 6, by exploiting amino acid transporters, can selectively deliver its toxic effects to Leishmania cells. This work provides the first evidence that amino acid transporters of the human pathogen Leishmania might be modulated by small molecules, and warrants their further investigation from drug discovery and chemical biology perspectives.

  7. Quinone-Amino Acid Conjugates Targeting Leishmania Amino Acid Transporters

    OpenAIRE

    Federica Prati; Adele Goldman-Pinkovich; Federica Lizzi; Federica Belluti; Roni Koren; Dan Zilberstein; Maria Laura Bolognesi

    2014-01-01

    The aim of the present study was to investigate the feasibility of targeting Leishmania transporters via appropriately designed chemical probes. Leishmania donovani, the parasite that causes visceral leishmaniasis, is auxotrophic for arginine and lysine and has specific transporters (LdAAP3 and LdAAP7) to import these nutrients. Probes 1-15 were originated by conjugating cytotoxic quinone fragments (II and III) with amino acids (i.e. arginine and lysine) by means of an amide linkage. The toxi...

  8. The contribution of SNAT1 to system A amino acid transporter activity in human placental trophoblast

    Energy Technology Data Exchange (ETDEWEB)

    Desforges, M., E-mail: michelle.desforges@manchester.ac.uk [Maternal and Fetal Health Research Centre, Developmental Biomedicine, School of Medicine, Manchester Academic Health Sciences Centre, University of Manchester, St. Mary' s Hospital, Level 5-Research, Oxford Road, Manchester M13 9WL (United Kingdom); Greenwood, S.L.; Glazier, J.D.; Westwood, M.; Sibley, C.P. [Maternal and Fetal Health Research Centre, Developmental Biomedicine, School of Medicine, Manchester Academic Health Sciences Centre, University of Manchester, St. Mary' s Hospital, Level 5-Research, Oxford Road, Manchester M13 9WL (United Kingdom)

    2010-07-16

    Research highlights: {yields} mRNA levels for SNAT1 are higher than other system A subtype mRNAs in primary human cytotrophoblast. {yields} SNAT1 knockdown in cytotrophoblast cells significantly reduces system A activity. {yields} SNAT1 is a key contributor to system A-mediated amino acid transport in human placenta. -- Abstract: System A-mediated amino acid transport across the placenta is important for the supply of neutral amino acids needed for fetal growth. All three system A subtypes (SNAT1, 2, and 4) are expressed in human placental trophoblast suggesting there is an important biological role for each. Placental system A activity increases as pregnancy progresses, coinciding with increased fetal nutrient demands. We have previously shown SNAT4-mediated system A activity is higher in first trimester than at term, suggesting that SNAT1 and/or SNAT2 are responsible for the increased system A activity later in gestation. However, the relative contribution of each subtype to transporter activity in trophoblast at term has yet to be evaluated. The purpose of this study was to identify the predominant subtype of system A in cytotrophoblast cells isolated from term placenta, maintained in culture for 66 h, by: (1) measuring mRNA expression of the three subtypes and determining the Michaelis-Menten constants for uptake of the system A-specific substrate, {sup 14}C-MeAIB, (2) investigating the contribution of SNAT1 to total system A activity using siRNA. Results: mRNA expression was highest for the SNAT1 subtype of system A. Kinetic analysis of {sup 14}C-MeAIB uptake revealed two distinct transport systems; system 1: K{sub m} = 0.38 {+-} 0.12 mM, V{sub max} = 27.8 {+-} 9.0 pmol/mg protein/20 min, which resembles that reported for SNAT1 and SNAT2 in other cell types, and system 2: K{sub m} = 45.4 {+-} 25.0 mM, V{sub max} = 1190 {+-} 291 pmol/mg protein/20 min, which potentially represents SNAT4. Successful knockdown of SNAT1 mRNA using target-specific si

  9. Glycinergic-Fipronil Uptake Is Mediated by an Amino Acid Carrier System and Induces the Expression of Amino Acid Transporter Genes in Ricinus communis Seedlings.

    Science.gov (United States)

    Xie, Yun; Zhao, Jun-Long; Wang, Chuan-Wei; Yu, Ai-Xin; Liu, Niu; Chen, Li; Lin, Fei; Xu, Han-Hong

    2016-05-18

    Phloem-mobile insecticides are efficient for piercing and sucking insect control. Introduction of sugar or amino acid groups to the parent compound can improve the phloem mobility of insecticides, so a glycinergic-fipronil conjugate (GlyF), 2-(3-(3-cyano-1-(2,6-dichloro-4-(trifluoromethyl)phenyl)-4-((trifluoromethyl)sulfinyl)-1H-pyrazole-5-yl)ureido) acetic acid, was designed and synthesized. Although the "Kleier model" predicted that this conjugate is not phloem mobile, GlyF can be continually detected during a 5 h collection of Ricinus communis phloem sap. Furthermore, an R. communis seedling cotyledon disk uptake experiment demonstrates that the uptake of GlyF is sensitive to pH, carbonyl cyanide m-chlorophenylhydrazone (CCCP), temperature, and p-chloromercuribenzenesulfonic acid (pCMBS) and is likely mediated by amino acid carrier system. To explore the roles of amino acid transporters (AATs) in GlyF uptake, a total of 62 AAT genes were identified from the R. communis genome in silico. Phylogenetic analysis revealed that AATs in R. communis were organized into the ATF (amino acid transporter) and APC (amino acid, polyaminem and choline transporter) superfamilies, with five subfamilies in ATF and two in APC. Furthermore, the expression profiles of 20 abundantly expressed AATs (cycle threshold (Ct) values communis seedlings. On the basis of the observation that the expression profile of the four candidate genes is similar to the time course observation for GlyF foliar disk uptake, it is suggested that those four genes are possible candidates involved in the uptake of GlyF. These results contribute to a better understanding of the mechanism of GlyF uptake as well as phloem loading from a molecular biology perspective and facilitate functional characterization of candidate AAT genes in future studies.

  10. The small SLC43 family: facilitator system l amino acid transporters and the orphan EEG1.

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    Bodoy, Susanna; Fotiadis, Dimitrios; Stoeger, Claudia; Kanai, Yoshikatsu; Palacín, Manuel

    2013-01-01

    The SLC43 family is composed of only three genes coding for the plasma membrane facilitator system l amino acid transporters LAT3 (SLC43A1; TC 2.A.1.44.1) and LAT4 (SLC43A2; TC 2.A.1.44.2), and the orphan protein EEG1 (SLC43A3; TC 2.A.1.44.3). Besides the known mechanism of transport of LAT3 and LAT4, their physiological roles still remain quite obscure. Morphants suggested a role of LAT3 in renal podocyte development in zebrafish. Expression in liver and skeletal muscle, and up-regulation by starvation suggest a role of LAT3 in the flux of branched-chain amino acids (BCAAs) from liver and skeletal muscle to the bloodstream. Finally, LAT3 is up-regulated in androgen-dependent cancers, suggesting a role in mTORC1 signaling in this type of tumors. In addition, LAT4 might contribute to the transfer of BCAAs from mother to fetus. Unfortunately, the EEG1 mouse model (EEG1(Y221∗)) described here has not yet offered a clue to the physiological role of this orphan protein.

  11. Biodistribution of [{sup 11}C] methylaminoisobutyric acid, a tracer for PET studies on system A amino acid transport in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Sutinen, E.; Jyrkkioe, S. [Dept. of Oncology and Radiotherapy, Turku University Central Hospital (Finland); Turku PET Centre, Turku University Central Hospital (Finland); Groenroos, T.; Haaparanta, M.; Lehikoinen, P.; Naagren, K. [Turku PET Centre, Turku University Central Hospital (Finland)

    2001-07-01

    [N-methyl-{sup 11}C]{alpha}-Methylaminoisobutyric acid ({sup 11}C-MeAIB) is a potentially useful tracer for positron emission tomography (PET) studies on hormonally regulated system A amino acid transport. {sup 11}C-MeAIB is a metabolically stable amino acid analogue specific for system A amino acid transport. We evaluated the biodistribution of {sup 11}C-MeAIB in rats and humans to estimate the usefulness of the tracer for in vivo human PET studies, for example, on regulation of system A amino acid transport and on tumour imaging. Healthy Sprague-Dawley rats (n=14) were killed 5, 20, 40 or 60 min after the injection of {sup 11}C-MeAIB, and the tissue samples were weighed and counted for {sup 11}C radioactivity. Ten lymphoma patients with relatively limited tumour burden underwent whole-body (WB) PET imaging with {sup 11}C-MeAIB. In addition, three other patients had dynamic PET scanning of the head and neck area, and the tracer uptake was quantitated by calculating the kinetic influx constants (K{sub i} values) for the tracer. In animal studies, the highest activity was detected in the kidney, pancreas, adrenal gland and intestines. In humans, the highest activity was found in the salivary glands, and after that in the kidney and pancreas, similar to the results in animal studies. Rapid uptake was also detected in the skeletal muscle. In the graphical analysis, linear plots were obtained, and the mean fractional tracer uptake values (K{sub i}) of the parotid glands (n=3) and cervical muscles (n=3) were 0.039{+-}0.008 min{sup -1} and 0.013{+-}0.006 min{sup -1}, respectively. The K{sub i} value of the tumour (n=1) was 0.064 min{sup -1}. Higher uptake of {sup 11}C-MeAIB into the tumour tissue was encountered. These results encourage further {sup 11}C-MeAIB PET studies in humans on the physiology and pathology of system A amino acid transport and on tumour detection. (orig.)

  12. Biodistribution of [11C] methylaminoisobutyric acid, a tracer for PET studies on system A amino acid transport in vivo

    International Nuclear Information System (INIS)

    [N-methyl-11C]α-Methylaminoisobutyric acid (11C-MeAIB) is a potentially useful tracer for positron emission tomography (PET) studies on hormonally regulated system A amino acid transport. 11C-MeAIB is a metabolically stable amino acid analogue specific for system A amino acid transport. We evaluated the biodistribution of 11C-MeAIB in rats and humans to estimate the usefulness of the tracer for in vivo human PET studies, for example, on regulation of system A amino acid transport and on tumour imaging. Healthy Sprague-Dawley rats (n=14) were killed 5, 20, 40 or 60 min after the injection of 11C-MeAIB, and the tissue samples were weighed and counted for 11C radioactivity. Ten lymphoma patients with relatively limited tumour burden underwent whole-body (WB) PET imaging with 11C-MeAIB. In addition, three other patients had dynamic PET scanning of the head and neck area, and the tracer uptake was quantitated by calculating the kinetic influx constants (Ki values) for the tracer. In animal studies, the highest activity was detected in the kidney, pancreas, adrenal gland and intestines. In humans, the highest activity was found in the salivary glands, and after that in the kidney and pancreas, similar to the results in animal studies. Rapid uptake was also detected in the skeletal muscle. In the graphical analysis, linear plots were obtained, and the mean fractional tracer uptake values (Ki) of the parotid glands (n=3) and cervical muscles (n=3) were 0.039±0.008 min-1 and 0.013±0.006 min-1, respectively. The Ki value of the tumour (n=1) was 0.064 min-1. Higher uptake of 11C-MeAIB into the tumour tissue was encountered. These results encourage further 11C-MeAIB PET studies in humans on the physiology and pathology of system A amino acid transport and on tumour detection. (orig.)

  13. Canine amino acid transport system Xc(-): cDNA sequence, distribution and cystine transport activity in lens epithelial cells.

    Science.gov (United States)

    Maruo, Takuya; Kanemaki, Nobuyuki; Onda, Ken; Sato, Reiichiro; Ichihara, Nobuteru; Ochiai, Hideharu

    2014-04-01

    The cystine transport activity of a lens epithelial cell line originated from a canine mature cataract was investigated. The distinct cystine transport activity was observed, which was inhibited to 28% by extracellular 1 mM glutamate. The cDNA sequences of canine cysteine/glutamate exchanger (xCT) and 4F2hc were determined. The predicted amino acid sequences were 527 and 533 amino acid polypeptides, respectively. The amino acid sequences of canine xCT and 4F2hc showed high similarities (>80%) to those of humans. The expression of xCT in lens epithelial cell line was confirmed by western blot analysis. RT-PCR analysis revealed high level expression only in the brain, and it was below the detectable level in other tissues.

  14. Protein Characterization of Na+-Independent System L Amino Acid Transporter 3 in Mice : A Potential Role in Supply of Branched-Chain Amino Acids under Nutrient Starvation

    OpenAIRE

    Fukuhara, Daisuke; Kanai, Yoshikatsu; Chairoungdua, Arthit; Babu, Ellappan; Bessho, Fumio; Kawano, Toshio; Akimoto, Yoshihiro; Endou, Hitoshi; Yan, Kunimasa

    2007-01-01

    We recently cloned the human Na+-independent system L neutral amino acid transporter LAT3. The aim of the present study was to characterize the molecular nature of mouse LAT3 at the protein level. Isolated mouse LAT3 showed 83% identity to human LAT3. Xenopus oocytes injected with mouse LAT3 cRNA showed the same functional property as human LAT3. Reverse transcriptase-polymerase chain reaction revealed apparent transcripts of mouse LAT3 in the liver, skeletal muscle, and pancreas, an expressi...

  15. Expression of heteromeric amino acid transporters along the murine intestine.

    Science.gov (United States)

    Dave, Mital H; Schulz, Nicole; Zecevic, Marija; Wagner, Carsten A; Verrey, Francois

    2004-07-15

    Members of the new heterodimeric amino acid transporter family are composed of two subunits, a catalytic multitransmembrane spanning protein (light chain) and a type II glycoprotein (heavy chain). These transporters function as exchangers and thereby extend the transmembrane amino acid transport selectivity to specific amino acids. The heavy chain rBAT associates with the light chain b degrees (,+)AT to form a cystine and cationic amino acid transporter. The other heavy chain, 4F2hc, can interact with seven different light chains to form various transporters corresponding to systems L, y(+)L, asc or x(-)(c). The importance of some of these transporters in intestinal and renal (re)absorption of amino acids is highlighted by the fact that mutations in either the rBAT or b degrees (,+)AT subunit result in cystinuria whereas a defect in the y(+)-LAT1 light chain causes lysinuric protein intolerance. Here we investigated the localization of these transporters in intestine since both diseases are also characterized by altered intestinal amino acid absorption. Real time PCR showed organ-specific expression patterns for all transporter subunit mRNAs along the intestine and Western blotting confirmed these findings on the protein level. Immunohistochemistry demonstrated basolateral coexpression of 4F2hc, LAT2 and y(+)-LAT1 in stomach and small intestine, whereas rBAT and b degrees (,+)AT were found colocalizing on the apical side of small intestine epithelium. In stomach, 4F2hc and LAT2 were localized in H(+)/K(+)-ATPase-expressing parietal cells. The abundant expression of several members of the heterodimeric transporter family along the murine small intestine suggests their involvement in amino acids absorption. Furthermore, strong expression of rBAT, b degrees (,+)AT and y(+)-LAT1 in the small intestine explains the reduced intestinal absorption of some amino acid in patients with cystinuria or lysinuric protein intolerance.

  16. Amino Acid Transporters and Release of Hydrophobic Amino Acids in the Heterocyst-Forming Cyanobacterium Anabaena sp. Strain PCC 7120

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    Rafael Pernil

    2015-04-01

    Full Text Available Anabaena sp. strain PCC 7120 is a filamentous cyanobacterium that can use inorganic compounds such as nitrate or ammonium as nitrogen sources. In the absence of combined nitrogen, it can fix N2 in differentiated cells called heterocysts. Anabaena also shows substantial activities of amino acid uptake, and three ABC-type transporters for amino acids have been previously characterized. Seven new loci encoding predicted amino acid transporters were identified in the Anabaena genomic sequence and inactivated. Two of them were involved in amino acid uptake. Locus alr2535-alr2541 encodes the elements of a hydrophobic amino acid ABC-type transporter that is mainly involved in the uptake of glycine. ORF all0342 encodes a putative transporter from the dicarboxylate/amino acid:cation symporter (DAACS family whose inactivation resulted in an increased uptake of a broad range of amino acids. An assay to study amino acid release from Anabaena filaments to the external medium was set up. Net release of the alanine analogue α-aminoisobutyric acid (AIB was observed when transport system N-I (a hydrophobic amino acid ABC-type transporter was engaged in the uptake of a specific substrate. The rate of AIB release was directly proportional to the intracellular AIB concentration, suggesting leakage from the cells by diffusion.

  17. System a amino acid transport-targeted brain and systemic tumor PET imaging agents 2-amino-3-[18 F]fluoro-2-methylpropanoic acid and 3-[18 F]fluoro-2-methyl-2-(methylamino)propanoic acid

    International Nuclear Information System (INIS)

    Introduction: Amino acid based radiotracers target tumor cells through increased uptake by membrane-associated amino acid transport (AAT) systems. In the present study, four structurally related non-natural 18 F-labeled amino acids, (R)- and (S)-[18 F]FAMP 1 and (R)- and (S)-[18 F]MeFAMP 2 have been prepared and evaluated in vitro and in vivo for their potential utility in brain and systemic tumor imaging based upon primarily system A transport with positron emission tomography (PET). Methods: The transport of enantiomers of [18 F]FAMP 1 and [18 F]MeFAMP 2 was measured through in vitro uptake assays in human derived cancer cells including A549 (lung), DU145 (prostate), SKOV3 (ovary), MDA MB468 (breast) and U87 (brain) in the presence and absence of amino acid transporter inhibitors. The in vivo biodistribution of these tracers was evaluated using tumor mice xenografts at 15, 30, 60 and 120 min post injection. Results: All four tracers showed moderate to high levels of uptake (1–9%ID/5 × 105 cells) by the cancer cell lines tested in vitro. AAT cell inhibition assays demonstrated that (R)-[18 F]1 and (S)-[18 F]1 entered these tumor cells via mixed AATs, likely but not limited to system A and system L. In contrast, (R)-[18 F]2 and (S)-[18 F]2 showed high selectivity for system A AAT. Similar to the results of in vitro cell studies, the tumor uptake of all four tracers was good to high and persisted over the 2 hours time course of in vivo studies. The accumulation of these tracers was higher in tumor than most normal tissues including blood, brain, muscle, bone, heart, and lung, and the tracers with the highest in vitro selectivity for system A AAT generally demonstrated the best tumor imaging properties. Higher uptake of these tracers was observed in the pancreas, kidney and spleen compared to tumors. Conclusions: These preclinical studies demonstrate good imaging properties in a wide range of tumors for all four amino acids evaluated with (R)-[18 F]2 having the

  18. The EGF Receptor Promotes the Malignant Potential of Glioma by Regulating Amino Acid Transport System xc(-).

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    Tsuchihashi, Kenji; Okazaki, Shogo; Ohmura, Mitsuyo; Ishikawa, Miyuki; Sampetrean, Oltea; Onishi, Nobuyuki; Wakimoto, Hiroaki; Yoshikawa, Momoko; Seishima, Ryo; Iwasaki, Yoshimi; Morikawa, Takayuki; Abe, Shinya; Takao, Ayumi; Shimizu, Misato; Masuko, Takashi; Nagane, Motoo; Furnari, Frank B; Akiyama, Tetsu; Suematsu, Makoto; Baba, Eishi; Akashi, Koichi; Saya, Hideyuki; Nagano, Osamu

    2016-05-15

    Extracellular free amino acids contribute to the interaction between a tumor and its microenvironment through effects on cellular metabolism and malignant behavior. System xc(-) is composed of xCT and CD98hc subunits and functions as a plasma membrane antiporter for the uptake of extracellular cystine in exchange for intracellular glutamate. Here, we show that the EGFR interacts with xCT and thereby promotes its cell surface expression and function in human glioma cells. EGFR-expressing glioma cells manifested both enhanced antioxidant capacity as a result of increased cystine uptake, as well as increased glutamate, which promotes matrix invasion. Imaging mass spectrometry also revealed that brain tumors formed in mice by human glioma cells stably overexpressing EGFR contained higher levels of reduced glutathione compared with those formed by parental cells. Targeted inhibition of xCT suppressed the EGFR-dependent enhancement of antioxidant capacity in glioma cells, as well as tumor growth and invasiveness. Our findings establish a new functional role for EGFR in promoting the malignant potential of glioma cells through interaction with xCT at the cell surface. Cancer Res; 76(10); 2954-63. ©2016 AACR.

  19. Osmotically inducible uptake of betaine via amino acid transport system A in SV-3T3 cells.

    Science.gov (United States)

    Petronini, P G; De Angelis, E; Borghetti, A F; Wheeler, K P

    1994-05-15

    The osmotically inducible uptake of betaine (NNN-trimethylglycine) by SV-3T3 cells has been studied and compared with the similar process in MDCK cells. Betaine uptake by SV-3T3 cells could be described in terms of a saturable, Na(+)-dependent, component plus a small non-saturable, Na(+)-independent, component. Transport was active, producing considerable accumulation of betaine in the cells. After exposure of the cells to hypertonic conditions for 6 h, there was a marked increase in betaine uptake. Kinetic analysis indicated that this increase resulted from an increase in the Vmax. value of the saturable component, from about 88 to 185 nmol of betaine/5 min per mg of protein, the corresponding Km values of about 15 and 10 mM not being significantly different. This induction of transport activity was detectable only after about 2 h exposure of the cells to hypertonic medium, closely paralleling an induction of influx of N-methylaminoisobutyric acid, and was prevented by the presence of cycloheximide. Betaine influx was markedly inhibited by several neutral amino acids, particularly those transported by system A, such as N-methylaminoisobutyric acid and the imino acid proline. A high concentration (25 mM) of betaine also significantly inhibited the uptake of proline by SV-3T3 cells. Although very similar results were obtained with MDCK cells, prolonged exposure of cells to hypertonic conditions revealed distinct differences. When the hypertonic incubation was extended from 6 h to 24 h, betaine transport in SV-3T3 cells either remained the same or decreased, whereas it showed a further marked increase in MDCK cells, and also became sensitive to inhibition by gamma-aminobutyric acid. mRNA for the betaine transporter BGT-1 [Yamauchi, Uchida, Kwon, Preston, Brooks Robey, Garcia-Perez, Burg and Handler (1992) J. Biol. Chem. 267, 649-652] was detectable in MDCK cells exposed to hypertonic medium for 24 h, but not in SV-3T3 cells under any conditions. It is concluded that

  20. Structural and functional dynamics of Excitatory Amino Acid Transporters (EAAT

    Directory of Open Access Journals (Sweden)

    Thomas Rauen

    2014-09-01

    Full Text Available Glutamate transporters control the glutamate homeostasis in the central nervous system, and, thus, are not only crucial for physiological excitatory synaptic signaling, but also for the prevention of a large number of neurodegenerative diseases that are associated with excessive and prolonged presence of the neurotransmitter glutamate in the extracellular space. Until now, five subtypes of high-affinity glutamate transporters (excitatory amino acid transporters, EAATs 1–5 have been identified. These 5 high-affinity glutamate transporter subtypes belong to the solute carrier 1 (SLC1 family of transmembrane proteins: EAAT1/GLAST (SLC1A3, EAAT2/GLT1 (SLC1A2, EAAT3/EAAC1 (SLC1A1, EAAT4 (SLC1A6 and EAAT5 (SLC1A7. EAATs are secondary-active transporters, taking up glutamate into the cell against a substantial concentration gradient. The driving force for concentrative uptake is provided by the co-transport of Na+ ions and the counter-transport of one K+ in a step independent of the glutamate translocation step. Due to the electrogenicity of transport, the transmembrane potential can also act as driving force. Glutamate transporters are also able to run in reverse, resulting in glutamate release from cells. Due to these important physiological functions, glutamate transporter expression and, therefore, the transport rate, are tightly regulated. The EAAT protein family are structurally expected to be highly similar, however, these transporters show a functional diversity that ranges from high capacity glutamate uptake systems (EAATs 1–3 to receptor-like glutamate activated anion channels (EAATs 4–5. Here, we provide an update on most recent progress made on EAAT’s molecular transport mechanism, structure-function relationships, pharmacology, and will add recent insights into mechanism of rapid membrane trafficking of glutamate transporters.

  1. Automated Synthesis of 18F-Fluoropropoxytryptophan for Amino Acid Transporter System Imaging

    Directory of Open Access Journals (Sweden)

    I-Hong Shih

    2014-01-01

    Full Text Available Objective. This study was to develop a cGMP grade of [18F]fluoropropoxytryptophan (18F-FTP to assess tryptophan transporters using an automated synthesizer. Methods. Tosylpropoxytryptophan (Ts-TP was reacted with K18F/kryptofix complex. After column purification, solvent evaporation, and hydrolysis, the identity and purity of the product were validated by radio-TLC (1M-ammonium acetate : methanol = 4 : 1 and HPLC (C-18 column, methanol : water = 7 : 3 analyses. In vitro cellular uptake of 18F-FTP and 18F-FDG was performed in human prostate cancer cells. PET imaging studies were performed with 18F-FTP and 18F-FDG in prostate and small cell lung tumor-bearing mice (3.7 MBq/mouse, iv. Results. Radio-TLC and HPLC analyses of 18F-FTP showed that the Rf and Rt values were 0.9 and 9 min, respectively. Radiochemical purity was >99%. The radiochemical yield was 37.7% (EOS 90 min, decay corrected. Cellular uptake of 18F-FTP and 18F-FDG showed enhanced uptake as a function of incubation time. PET imaging studies showed that 18F-FTP had less tumor uptake than 18F-FDG in prostate cancer model. However, 18F-FTP had more uptake than 18F-FDG in small cell lung cancer model. Conclusion. 18F-FTP could be synthesized with high radiochemical yield. Assessment of upregulated transporters activity by 18F-FTP may provide potential applications in differential diagnosis and prediction of early treatment response.

  2. Amino Acid Transport System N: Molecular Structure, Distribution and Functional Analysis of Canine SLC38A5 (SNAT5) in Lens Epithelial Cells.

    OpenAIRE

    2014-01-01

    Na-dependent of neutral amino acid transport activity in canine lens epithelial cells (LEC) line was investigated. The transporter activity of glutamine was 11.17 ± 3.17 nmol/mg protein/min, and it was reduced by 75% in the absence of sodium. The full-length cDNA sequence of canine sodium-dependent neutral amino acid transporter 5 (SNAT5) was 2151 bp long and was predicted to encode the 536 amino acid polypeptides. The deduced amino acid sequence of canine SNAT5 showed >80% similarities with ...

  3. Transport of aromatic amino acids by Brevibacterium linens.

    OpenAIRE

    Boyaval, P; Moreira, E; Desmazeaud, M. J.

    1983-01-01

    Whole metabolizing Brevibacterium linens cells were used to study the transport of aromatic amino acids. Kinetic results followed the Michaelis-Menten equation with apparent Km values for phenylalanine, tyrosine, and tryptophan of 24, 3.5, and 1.8 microM. Transport of these amino acids was optimum at pH 7.5 and 25 degrees C for phenylalanine and pH 8.0 and 35 degrees C for tyrosine and tryptophan. Crossed inhibitions were all noncompetitive. The only marked stereospecificity was for the L for...

  4. Amino acids

    Science.gov (United States)

    ... amino acids are: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan , and valine. Nonessential amino acids "Nonessential" means that our bodies produce an amino ...

  5. Plasmodium falciparum malaria elicits inflammatory responses that dysregulate placental amino acid transport.

    Directory of Open Access Journals (Sweden)

    Philippe Boeuf

    2013-02-01

    Full Text Available Placental malaria (PM can lead to poor neonatal outcomes, including low birthweight due to fetal growth restriction (FGR, especially when associated with local inflammation (intervillositis or IV. The pathogenesis of PM-associated FGR is largely unknown, but in idiopathic FGR, impaired transplacental amino acid transport, especially through the system A group of amino acid transporters, has been implicated. We hypothesized that PM-associated FGR could result from impairment of transplacental amino acid transport triggered by IV. In a cohort of Malawian women and their infants, the expression and activity of system A (measured by Na⁺-dependent ¹⁴C-MeAIB uptake were reduced in PM, especially when associated with IV, compared to uninfected placentas. In an in vitro model of PM with IV, placental cells exposed to monocyte/infected erythrocytes conditioned medium showed decreased system A activity. Amino acid concentrations analyzed by reversed phase ultra performance liquid chromatography in paired maternal and cord plasmas revealed specific alterations of amino acid transport by PM, especially with IV. Overall, our data suggest that the fetoplacental unit responds to PM by altering its placental amino acid transport to maintain adequate fetal growth. However, IV more profoundly compromises placental amino acid transport function, leading to FGR. Our study offers the first pathogenetic explanation for FGR in PM.

  6. Neutral amino acid transport across brain microvessel endothelial cell monolayers

    International Nuclear Information System (INIS)

    Brain microvessel endothelial cells (BMEC) which form the blood-brain barrier (BBB) possess an amino acid carrier specific for large neutral amino acids (LNAA). The carrier is important for facilitating the delivery of nutrient LNAA's and centrally acting drugs that are LNAA's, to the brain. Bovine BMEC's were isolated and grown up to complete monolayers on regenerated cellulose-membranes in primary culture. To study the transendothelial transport of leucine, the monolayers were placed in a side-by-side diffusion cell, and transport across the monolayers followed with [3H]-leucine. The transendothelial transport of leucine in this in vitro model was determined to be bidirectional, and time-, temperature-, and concentration-dependent. The transport of leucine was saturable and the apparent K/sub m/ and V/sub max/, 0.18 mM and 6.3 nmol/mg/min, respectively. Other LNAA's, including the centrally acting drugs, α-methyldopa, L-DOPA, α-methyl-tyrosine, and baclofen, inhibited leucine transport. The leucine carrier was also found to be stereospecific and not sensitive to inhibitors of active transport. These results are consistent with previous in vitro and in vivo studies. Primary cultures of BMEC's appear to be a potentially important tool for investigating at the cellular level, the transport mechanisms of the BBB

  7. Neutral amino acid transport across brain microvessel endothelial cell monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Audus, K.L.; Borchardt, R.T.

    1986-03-01

    Brain microvessel endothelial cells (BMEC) which form the blood-brain barrier (BBB) possess an amino acid carrier specific for large neutral amino acids (LNAA). The carrier is important for facilitating the delivery of nutrient LNAA's and centrally acting drugs that are LNAA's, to the brain. Bovine BMEC's were isolated and grown up to complete monolayers on regenerated cellulose-membranes in primary culture. To study the transendothelial transport of leucine, the monolayers were placed in a side-by-side diffusion cell, and transport across the monolayers followed with (/sup 3/H)-leucine. The transendothelial transport of leucine in this in vitro model was determined to be bidirectional, and time-, temperature-, and concentration-dependent. The transport of leucine was saturable and the apparent K/sub m/ and V/sub max/, 0.18 mM and 6.3 nmol/mg/min, respectively. Other LNAA's, including the centrally acting drugs, ..cap alpha..-methyldopa, L-DOPA, ..cap alpha..-methyl-tyrosine, and baclofen, inhibited leucine transport. The leucine carrier was also found to be stereospecific and not sensitive to inhibitors of active transport. These results are consistent with previous in vitro and in vivo studies. Primary cultures of BMEC's appear to be a potentially important tool for investigating at the cellular level, the transport mechanisms of the BBB.

  8. Excitatory amino acid transporters as potential drug targets

    DEFF Research Database (Denmark)

    Bunch, Lennart; Erichsen, Mette Navy; Jensen, Anders Asbjørn

    2009-01-01

    BACKGROUND: Excitatory amino acid transporters (EAATs) are transmembrane proteins responsible for the uptake of (S)-glutamate (Glu) from the synaptic cleft, thereby terminating the glutamatergic neurotransmitter signal. Today five subtypes have been identified. Except for EAAT2, their individual...... and detailed understanding of EAATs be obtained. Thus we encourage collaboration between organic chemists and molecular pharmacologists, who, together, may pave the way for new EAAT ligands of importance....

  9. Expression pattern of peptide and amino acid genes in digestive tract of transporter juvenile turbot ( Scophthalmus maximus L.)

    Science.gov (United States)

    Xu, Dandan; He, Gen; Mai, Kangsen; Zhou, Huihui; Xu, Wei; Song, Fei

    2016-04-01

    Turbot ( Scophthalmus maximus L.), a carnivorous fish species with high dietary protein requirement, was chosen to examine the expression pattern of peptide and amino acid transporter genes along its digestive tract which was divided into six segments including stomach, pyloric caeca, rectum, and three equal parts of the remainder of the intestine. The results showed that the expression of two peptide and eleven amino acid transporters genes exhibited distinct patterns. Peptide transporter 1 (PepT1) was rich in proximal intestine while peptide transporter 2 (PepT2) was abundant in distal intestine. A number of neutral and cationic amino acid transporters expressed richly in whole intestine including B0-type amino acid transporter 1 (B0AT1), L-type amino acid transporter 2 (LAT2), T-type amino acid transporter 1 (TAT1), proton-coupled amino acid transporter 1 (PAT1), y+L-type amino acid transporter 1 (y+LAT1), and cationic amino acid transporter 2 (CAT2) while ASC amino acid transporter 2 (ASCT2), sodium-coupled neutral amino acid transporter 2 (SNAT2), and y+L-type amino acid transporter 2 (y+LAT2) abundantly expressed in stomach. In addition, system b0,+ transporters (rBAT and b0,+AT) existed richly in distal intestine. These findings comprehensively characterized the distribution of solute carrier family proteins, which revealed the relative importance of peptide and amino acid absorption through luminal membrane. Our findings are helpful to understand the mechanism of the utilization of dietary protein in fish with a short digestive tract.

  10. The putative Cationic Amino acid Transporter 9 is targeted to vesicles and may be involved in plant amino acid homeostasis

    Directory of Open Access Journals (Sweden)

    Huaiyu eYang

    2015-04-01

    Full Text Available Amino acids are major primary metabolites. Their uptake, translocation, compartmentation and re-mobilization require a diverse set of cellular transporters. Here, the broadly expressed gene product of CATIONIC AMINO ACID TRANSPORTER 9 (CAT9 was identified as mainly localized to vesicular membranes that are involved in vacuolar trafficking, including those of the trans-Golgi network. In order to probe whether and how these compartments are involved in amino acid homeostasis, a loss-of-function cat9-1 mutant and ectopic over-expressor plants were isolated. Under restricted nitrogen supply in soil, cat9-1 showed a chlorotic phenotype, which was reversed in the over-expressors. The total soluble amino acid pools were affected in the mutants, but this was only significant under poor nitrogen supply. Upon nitrogen starvation, the major soluble amino acid leaf pools decreased. This decrease was lower in cat9-1 and augmented in the over-expressor. Over-expression generally affected total soluble amino acid concentrations and finally improved the survival upon severe nitrogen starvation. The results potentially identify a novel function of vesicular amino acid transport mediated by CAT9 in the cellular nitrogen-dependent amino acid homeostasis.

  11. Molecular and Functional Characterisation of a new Mammalian Family of Proton-coupled Amino Acid Transporters

    OpenAIRE

    Foltz, Martin

    2006-01-01

    Proton-coupled amino acid transport (PAT) systems in the apical membrane of epithelial cells of the small intestine and the renal tubule have been demonstrated by use of the human intestinal cell line Caco-2 and renal brush border membrane vesicles. The present thesis summarises the revelation of the molecular entity of the PAT system and provides deeper insights into this new mammalian family of proton/amino acid cotransporters. The identified family comprises four structural similar murine ...

  12. Expression cloning of a Na(+)-independent neutral amino acid transporter from rat kidney.

    OpenAIRE

    Tate, S S; Yan, N; Udenfriend, S

    1992-01-01

    Uptake of long-chain and aromatic neutral amino acids into cells is known to be catalyzed by the Na(+)-independent system L transporter, which is ubiquitous in animal cells and tissues. We have used a Xenopus oocyte expression system to clone the cDNA of a system L transporter from a rat kidney cDNA library. The 2.3-kilobase cDNA codes for a protein of 683 amino acids. The transporter has four putative membrane-spanning domains and bears no sequence or structural homology to any known animal ...

  13. Light-activated amino acid transport in Halobacterium halobium envelope vesicles

    Science.gov (United States)

    Macdonald, R. E.; Lanyi, J. K.

    1977-01-01

    Vesicles prepared from Halobacterium halobium cell envelopes accumulate amino acids in response to light-induced electrical and chemical gradients. Nineteen of 20 commonly occurring amino acids have been shown to be actively accumulated by these vesicles in response to illumination or in response to an artificially created Na+ gradient. On the basis of shared common carriers the transport systems can be divided into eight classes, each responsible for the transport of one or several amino acids: arginine, lysine, histidine; asparagine, glutamine; alanine, glycine, threonine, serine; leucine, valine, isoleucine, methionine; phenylalanine, tyrosine, tryptophan; aspartate; glutamate; proline. Available evidence suggests that these carriers are symmetrical in that amino acids can be transported equally well in both directions across the vesicle membranes. A tentative working model to account for these observations is presented.

  14. Transport and signaling via the amino acid binding site of the yeast Gap1 amino acid transceptor.

    Science.gov (United States)

    Van Zeebroeck, Griet; Bonini, Beatriz Monge; Versele, Matthias; Thevelein, Johan M

    2009-01-01

    Transporter-related nutrient sensors, called transceptors, mediate nutrient activation of signaling pathways through the plasma membrane. The mechanism of action of transporting and nontransporting transceptors is unknown. We have screened 319 amino acid analogs to identify compounds that act on Gap1, a transporting amino acid transceptor in yeast that triggers activation of the protein kinase A pathway. We identified competitive and noncompetitive inhibitors of transport, either with or without agonist action for signaling, including nontransported agonists. Using substituted cysteine accessibility method (SCAM) analysis, we identified Ser388 and Val389 as being exposed into the amino acid binding site, and we show that agonist action for signaling uses the same binding site as used for transport. Our results provide the first insight, to our knowledge, into the mechanism of action of transceptors. They indicate that signaling requires a ligand-induced specific conformational change that may be part of but does not require the complete transport cycle. PMID:19060912

  15. Extraction and Transport of Amino Acids Using Kryptofix 5 as Carrier through Liquid Membrane

    OpenAIRE

    Pankaj Raizada; Uma Sharma

    2013-01-01

    The present work explores membrane-mediated extraction and transport studies of amino acids through artificial bulk liquid membrane system with kryptofix 5 as a carrier. The various reaction parameters such as amino acid concentration, carrier concentration, time, pH, and stirring effect were studied to optimize reaction conditions. The stirring of source and receiving phases increased the efficiency of extraction process. Noncyclic receptor kryptofix 5 with five oxyethylene units an...

  16. The D‐amino acid transport by the invertebrate SLC6 transporters KAAT1 and CAATCH1 from Manduca sexta

    OpenAIRE

    Vollero, Alessandra; Imperiali, Francesca G.; Cinquetti, Raffaella; Margheritis, Eleonora; Peres, Antonio; Bossi, Elena

    2016-01-01

    Abstract The ability of the SLC6 family members, the insect neutral amino acid cotransporter KAAT1(K+‐coupled amino acid transporter 1) and its homologous CAATCH1(cation anion activated amino acid transporter/channel), to transport D‐amino acids has been investigated through heterologous expression in Xenopus laevis oocytes and electrophysiological techniques. In the presence of D‐isomers of leucine, serine, and proline, the ms KAAT1 generates inward, transport‐associated, currents with varia...

  17. Amino acid transport in taxonomically diverse cyanobacteria and identification of two genes encoding elements of a neutral amino acid permease putatively involved in recapture of leaked hydrophobic amino acids.

    Science.gov (United States)

    Montesinos, M L; Herrero, A; Flores, E

    1997-02-01

    The activities of uptake of thirteen 14C-labeled amino acids were determined in nine cyanobacteria, including the unicellular strains Synechococcus sp. strain PCC 7942 and Synechocystis sp. strain PCC 6803; the filamentous strain Pseudanabaena sp. strain PCC 6903, and the filamentous, heterocyst-forming strains Anabaena sp. strains PCC 7120 and PCC 7937; Nostoc sp. strains PCC 7413 and PCC 7107; Calothrix sp. strain PCC 7601 (which is a mutant unable to develop heterocysts); and Fischerella muscicola UTEX 1829. Amino acid transport mutants, selected as mutants resistant to some amino acid analogs, were isolated from the Anabaena, Nostoc, Calothrix, and Pseudanabaena strains. All of the tested cyanobacteria bear at least a neutral amino acid transport system, and some strains also bear transport systems specific for basic or acidic amino acids. Two genes, natA and natB, encoding elements (conserved component, NatA, and periplasmic binding protein, NatB) of an ABC-type permease for neutral amino acids were identified by insertional mutagenesis of strain PCC 6803 open reading frames from the recently published genomic DNA sequence of this cyanobacterium. DNA sequences homologous to natA and natB from strain PCC 6803 were detected by hybridization in eight cyanobacterial strains tested. Mutants unable to transport neutral amino acids, including natA and natB insertional mutants, accumulated in the extracellular medium a set of amino acids that always included Ala, Val, Phe, Ile, and Leu. A general role for a cyanobacterial neutral amino acid permease in recapture of hydrophobic amino acids leaked from the cells is suggested.

  18. A plasma membrane association module in yeast amino acid transporters

    NARCIS (Netherlands)

    Popov-Čeleketić, Dušan; Bianchi, Frans; Ruiz, Stephanie J; Meutiawati, Febrina; Poolman, Bert

    2016-01-01

    Amino acid permeases (AAPs) in the plasma membrane (PM) of Saccharomyces cerevisiae are responsible for the uptake of amino acids and involved in regulation of their cellular levels. Here, we report on a strong and complex module for PM association found in the C-terminal tail of AAPs. Using in sili

  19. Aphid amino acid transporter regulates glutamine supply to intracellular bacterial symbionts.

    Science.gov (United States)

    Price, Daniel R G; Feng, Honglin; Baker, James D; Bavan, Selvan; Luetje, Charles W; Wilson, Alex C C

    2014-01-01

    Endosymbiotic associations have played a major role in evolution. However, the molecular basis for the biochemical interdependence of these associations remains poorly understood. The aphid-Buchnera endosymbiosis provides a powerful system to elucidate how these symbioses are regulated. In aphids, the supply of essential amino acids depends on an ancient nutritional symbiotic association with the gamma-proteobacterium Buchnera aphidicola. Buchnera cells are densely packed in specialized aphid bacteriocyte cells. Here we confirm that five putative amino acid transporters are highly expressed and/or highly enriched in Acyrthosiphon pisum bacteriocyte tissues. When expressed in Xenopus laevis oocytes, two bacteriocyte amino acid transporters displayed significant levels of glutamine uptake, with transporter ACYPI001018, LOC100159667 (named here as Acyrthosiphon pisum glutamine transporter 1, ApGLNT1) functioning as the most active glutamine transporter. Transporter ApGLNT1 has narrow substrate selectivity, with high glutamine and low arginine transport capacity. Notably, ApGLNT1 has high binding affinity for arginine, and arginine acts as a competitive inhibitor for glutamine transport. Using immunocytochemistry, we show that ApGLNT1 is localized predominantly to the bacteriocyte plasma membrane, a location consistent with the transport of glutamine from A. pisum hemolymph to the bacteriocyte cytoplasm. On the basis of functional transport data and localization, we propose a substrate feedback inhibition model in which the accumulation of the essential amino acid arginine in A. pisum hemolymph reduces the transport of the precursor glutamine into bacteriocytes, thereby regulating amino acid biosynthesis in the bacteriocyte. Structural similarities in the arrangement of hosts and symbionts across endosymbiotic systems suggest that substrate feedback inhibition may be mechanistically important in other endosymbioses.

  20. Evolutionary systems biology of amino acid biosynthetic cost in yeast.

    Directory of Open Access Journals (Sweden)

    Michael D Barton

    Full Text Available Every protein has a biosynthetic cost to the cell based on the synthesis of its constituent amino acids. In order to optimise growth and reproduction, natural selection is expected, where possible, to favour the use of proteins whose constituents are cheaper to produce, as reduced biosynthetic cost may confer a fitness advantage to the organism. Quantifying the cost of amino acid biosynthesis presents challenges, since energetic requirements may change across different cellular and environmental conditions. We developed a systems biology approach to estimate the cost of amino acid synthesis based on genome-scale metabolic models and investigated the effects of the cost of amino acid synthesis on Saccharomyces cerevisiae gene expression and protein evolution. First, we used our two new and six previously reported measures of amino acid cost in conjunction with codon usage bias, tRNA gene number and atomic composition to identify which of these factors best predict transcript and protein levels. Second, we compared amino acid cost with rates of amino acid substitution across four species in the genus Saccharomyces. Regardless of which cost measure is used, amino acid biosynthetic cost is weakly associated with transcript and protein levels. In contrast, we find that biosynthetic cost and amino acid substitution rates show a negative correlation, but for only a subset of cost measures. In the economy of the yeast cell, we find that the cost of amino acid synthesis plays a limited role in shaping transcript and protein expression levels compared to that of translational optimisation. Biosynthetic cost does, however, appear to affect rates of amino acid evolution in Saccharomyces, suggesting that expensive amino acids may only be used when they have specific structural or functional roles in protein sequences. However, as there appears to be no single currency to compute the cost of amino acid synthesis across all cellular and environmental

  1. Human radiation dosimetry of [{sup 11}C]MeAIB, a new tracer for imaging of system A amino acid transport

    Energy Technology Data Exchange (ETDEWEB)

    Tolvanen, Tuula; Havu-Auren, Katja; Kotoneva, Eira [Turku University Hospital, Turku PET Centre, P.O. Box 52, Turku (Finland); Naagren, Kjell; Yu, Meixiang [Radiopharmaceutical Chemistry Laboratory, Turku PET Centre, Turku (Finland); Sutinen, Eija; Jyrkkioe, Sirkku [Turku University Hospital, Department of Oncology and Radiotherapy, Turku (Finland); Asola, Markku [Satakunta Central Hospital, Pori (Finland); Nuutila, Pirjo [Turku University Hospital, Turku PET Centre, P.O. Box 52, Turku (Finland); Turku University Hospital, Department of Medicine, Turku (Finland); Minn, Heikki [Turku University Hospital, Turku PET Centre, P.O. Box 52, Turku (Finland); Turku University Hospital, Department of Oncology and Radiotherapy, Turku (Finland)

    2006-10-15

    [N-methyl-{sup 11}C]{alpha}-methylaminoisobutyric acid ([{sup 11}C]MeAIB) is a promising positron emission tomography (PET) tracer for imaging hormonally regulated system A amino acid transport. Uptake of [{sup 11}C]MeAIB is totally specific for amino acid transport since [{sup 11}C]MeAIB is metabolically stable both extra- and intracellularly. The aim of this study was to measure cumulated radioactivity in different organs and estimate the absorbed radiation doses to humans with the Medical Internal Radiation Dosimetry (MIRD) method. Radiation absorbed doses were calculated from PET images for 25 volunteers. Dynamic acquisition data were obtained for the thoracic, abdominal, femoral and head and neck regions. The median dose of intravenously injected [{sup 11}C]MeAIB was 422{+-}35 MBq, with a range of 295-493 MBq. After PET imaging the radioactivity in voided urine was measured. Experimental human data were used for residence time estimates. Radiation doses were calculated with commonly used software. The effective dose for a 70-kg adult was 0.004 mSv/MBq, corresponding to a 1.72 mSv effective dose from the PET study with injection of 430 MBq [{sup 11}C]MeAIB. The highest absorbed doses were in the pancreas (0.018 mGy/MBq), kidneys (0.017 mGy/MBq), intestine (0.014 mGy/MBq), liver (0.008 mGy/MBq) and stomach (0.005 mGy/MBq). Only 0.57% of injected activity was excreted to urine within 1 h after injection. Biodistribution of [{sup 11}C]MeAIB in the abdominal region reflected the high activity of the transportation of amino acids via system A and these organs also had the highest radiation doses. An effective dose of 0.004 mSv/MBq is fully justified when [{sup 11}C]MeAIB PET is performed to study system A activity in vivo. (orig.)

  2. Induction of amino acid transporters expression by endurance exercise in rat skeletal muscle

    Energy Technology Data Exchange (ETDEWEB)

    Murakami, Taro, E-mail: tamuraka@sgk.ac.jp; Yoshinaga, Mariko

    2013-10-04

    Highlights: •Regulation of amino acid transporter expression in working muscle remains unclear. •Expression of amino acid transporters for leucine were induced by a bout of exercise. •Requirement of leucine in muscle cells might regulate expression of its transporters. •This information is beneficial for understanding the muscle remodeling by exercise. -- Abstract: We here investigated whether an acute bout of endurance exercise would induce the expression of amino acid transporters that regulate leucine transport across plasma and lysosomal membranes in rat skeletal muscle. Rats ran on a motor-driven treadmill at a speed of 28 m/min for 90 min. Immediately after the exercise, we observed that expression of mRNAs encoding L-type amino acid transporter 1 (LAT1) and CD98 was induced in the gastrocnemius, soleus, and extensor digitorum longus (EDL) muscles. Sodium-coupled neutral amino acid transporter 2 (SNAT2) mRNA was also induced by the exercise in those three muscles. Expression of proton-assisted amino acid transporter 1 (PAT1) mRNA was slightly but not significantly induced by a single bout of exercise in soleus and EDL muscles. Exercise-induced mRNA expression of these amino acid transporters appeared to be attenuated by repeated bouts of the exercise. These results suggested that the expression of amino acid transporters for leucine may be induced in response to an increase in the requirement for this amino acid in the cells of working skeletal muscles.

  3. Transport of D-serine via the amino acid transporter ATB(0,+) expressed in the colon.

    Science.gov (United States)

    Hatanaka, Takahiro; Huang, Wei; Nakanishi, Takeo; Bridges, Christy C; Smith, Sylvia B; Prasad, Puttur D; Ganapathy, Malliga E; Ganapathy, Vadivel

    2002-02-22

    D-Serine, synthesized endogenously in the brain, is an important modulator of glutamatergic neurotransmission. Since colonic bacteria produce D-serine, we asked the question whether there are transport mechanisms in the colon that might make this exogenously produced D-serine available to the host. Here we identify for the first time an amino acid transporter in the intestine for high-affinity active transport of D-serine. This transporter, called ATB(0,+), is a Na(+)- and Cl(-)-coupled transporter for L-enantiomers of neutral and cationic amino acids. Here we demonstrate that ATB(0,+) is also capable of mediating the Na(+)- and Cl(-)-coupled transport of D-serine. The affinity of ATB(0,+) for L-serine and D-serine is similar, the K(t) value for the two enantiomers being approximately 150 microM. In addition to D-serine, ATB(0,+) transports D-alanine, D-methionine, D-leucine, and D-tryptophan. However, several other neutral and cationic amino acids that are transportable substrates for ATB(0,+) as L-enantiomers are not transported when presented as D-enantiomers. ATB(0,+) is expressed in the intestinal tract, interestingly not in the proximal intestine but in the distal intestine. Expression is most predominant in the colon where the transporter is localized to the luminal membrane of colonocytes, making this transporter uniquely suitable for absorption of bacteria-derived D-serine. PMID:11846403

  4. Amino acid absorption and homeostasis in mice lacking the intestinal peptide transporter PEPT1.

    Science.gov (United States)

    Nässl, Anna-Maria; Rubio-Aliaga, Isabel; Fenselau, Henning; Marth, Mena Katharina; Kottra, Gabor; Daniel, Hannelore

    2011-07-01

    The intestinal peptide transporter PEPT1 mediates the uptake of di- and tripeptides derived from dietary protein breakdown into epithelial cells. Whereas the transporter appears to be essential to compensate for the reduced amino acid delivery in patients with mutations in amino acid transporter genes, such as in cystinuria or Hartnup disease, its physiological role in overall amino acid absorption is still not known. To assess the quantitative importance of PEPT1 in overall amino acid absorption and metabolism, PEPT1-deficient mice were studied by using brush border membrane vesicles, everted gut sacs, and Ussing chambers, as well as by transcriptome and proteome analysis of intestinal tissue samples. Neither gene expression nor proteome profiling nor functional analysis revealed evidence for any compensatory changes in the levels and/or function of transporters for free amino acids in the intestine. However, most plasma amino acid levels were increased in Pept1(-/-) compared with Pept1(+/+) animals, suggesting that amino acid handling is altered. Plasma appearance rates of (15)N-labeled amino acids determined after intragastric administration of a low dose of protein remained unchanged, whereas administration of a large protein load via gavage revealed marked differences in plasma appearance of selected amino acids. PEPT1 seems, therefore, important for overall amino acid absorption only after high dietary protein intake when amino acid transport processes are saturated and PEPT1 can provide additional absorption capacity. Since renal amino acid excretion remained unchanged, elevated basal concentrations of plasma amino acids in PEPT1-deficient animals seem to arise mainly from alterations in hepatic amino acid metabolism. PMID:21350187

  5. Transport of d-Serine via the Amino Acid Transporter ATB0,+ Expressed in the Colon

    OpenAIRE

    Hatanaka, Takahiro; Huang, Wei; Nakanishi, Takeo; Bridges, Christy C.; Smith, Sylvia B.; Prasad, Puttur D; Ganapathy, Malliga E.; Ganapathy, Vadivel

    2002-01-01

    d-Serine, synthesized endogenously in the brain, is an important modulator of glutamatergic neurotransmission. Since colonic bacteria produce d-serine, we asked the question whether there are transport mechanisms in the colon that might make this exogenously produced d-serine available to the host. Here we identify for the first time an amino acid transporter in the intestine for high-affinity active transport of d-serine. This transporter, called ATB0,+, is a Na+- and Cl−-coupled transporter...

  6. Liquid Membrane Transport Behavior of Functional Substituted Crown Ethers for Amino Acids

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Three functional substituted crown ethers were synthesized as liquid membrane transport carriers for amino acids. The result obtained shows that this kind of ditopic ligands can transport sodium salt of amino acids in good rate value especially the one with two pyridinyl groups as binding site outside the macrocycle.

  7. Designing Novel Nanoformulations Targeting Glutamate Transporter Excitatory Amino Acid Transporter 2: Implications in Treating Drug Addiction

    OpenAIRE

    Rao, PSS; Yallapu, Murali M.; Sari, Youssef; Fisher, Paul B.; Kumar, Santosh

    2015-01-01

    Chronic drug abuse is associated with elevated extracellular glutamate concentration in the brain reward regions. Deficit of glutamate clearance has been identified as a contributing factor that leads to enhanced glutamate concentration following extended drug abuse. Importantly, normalization of glutamate level through induction of glutamate transporter 1 (GLT1)/ excitatory amino acid transporter 2 (EAAT2) expression has been described in several in vivo studies. GLT1 upregulators including ...

  8. Identification of a disulfide bridge important for transport function of SNAT4 neutral amino acid transporter.

    Directory of Open Access Journals (Sweden)

    Rugmani Padmanabhan Iyer

    Full Text Available SNAT4 is a member of system N/A amino acid transport family that primarily expresses in liver and muscles and mediates the transport of L-alanine. However, little is known about the structure and function of the SNAT family of transporters. In this study, we showed a dose-dependent inhibition in transporter activity of SNAT4 with the treatment of reducing agents, dithiothreitol (DTT and Tris(2-carboxyethylphosphine (TCEP, indicating the possible involvement of disulfide bridge(s. Mutation of residue Cys-232, and the two highly conserved residues Cys-249 and Cys-321, compromised the transport function of SNAT4. However, this reduction was not caused by the decrease of SNAT4 on the cell surface since the cysteine-null mutant generated by replacing all five cysteines with alanine was equally capable of being expressed on the cell surface as wild-type SNAT4. Interestingly, by retaining two cysteine residues, 249 and 321, a significant level of L-alanine uptake was restored, indicating the possible formation of disulfide bond between these two conserved residues. Biotinylation crosslinking of free thiol groups with MTSEA-biotin provided direct evidence for the existence of a disulfide bridge between Cys-249 and Cys-321. Moreover, in the presence of DTT or TCEP, transport activity of the mutant retaining Cys-249 and Cys-321 was reduced in a dose-dependent manner and this reduction is gradually recovered with increased concentration of H2O2. Disruption of the disulfide bridge also decreased the transport of L-arginine, but to a lesser degree than that of L-alanine. Together, these results suggest that cysteine residues 249 and 321 form a disulfide bridge, which plays an important role in substrate transport but has no effect on trafficking of SNAT4 to the cell surface.

  9. Extraction and Transport of Amino Acids Using Kryptofix 5 as Carrier through Liquid Membrane

    Directory of Open Access Journals (Sweden)

    Pankaj Raizada

    2013-01-01

    Full Text Available The present work explores membrane-mediated extraction and transport studies of amino acids through artificial bulk liquid membrane system with kryptofix 5 as a carrier. The various reaction parameters such as amino acid concentration, carrier concentration, time, pH, and stirring effect were studied to optimize reaction conditions. The stirring of source and receiving phases increased the efficiency of extraction process. Noncyclic receptor kryptofix 5 with five oxyethylene units and terminal aromatic donor end groups governs its transport and extraction efficiency. The extraction and transport efficiency followed the following trend: valine > alanine > glycine > threonine. Supported liquid membrane (SLM studies were performed using cellulose nitrate, PTFE, eggshell, and onion membranes. The egg shell membrane support proved to be most efficient due to intricate network of water insoluble proteins fibers with very high surface area and homogeneity.

  10. Transport of amino acids and GABA analogues via the human proton-coupled amino acid transporter, hPAT1

    DEFF Research Database (Denmark)

    Larsen, Mie; Larsen, Birger Brodin; Frølund, Bente;

    2008-01-01

    and Pro in Caco-2 cell monolayers is hPAT1-mediated. The apical uptake of Pro is decreased at apical hyperosmolarity conditions. Furthermore we identified the two GABA-analogues, muscimol and THPO as novel hPAT1 substrates. THPO had an affinity for hPAT1 of 11.3mM, whereas muscimol had one of the highest......, which has been shown to function as a carboxylic acid bioisostere for substrates of the GABA receptor and transport systems....

  11. Amino Acid Synthesis in a Supercritical Carbon Dioxide - Water System

    Directory of Open Access Journals (Sweden)

    Akiyoshi Hoshino

    2009-06-01

    Full Text Available Mars is a CO2-abundant planet, whereas early Earth is thought to be also CO2-abundant. In addition, water was also discovered on Mars in 2008. From the facts and theory, we assumed that soda fountains were present on both planets, and this affected amino acid synthesis. Here, using a supercritical CO2/liquid H2O (10:1 system which mimicked crust soda fountains, we demonstrate production of amino acids from hydroxylamine (nitrogen source and keto acids (oxylic acid sources. In this research, several amino acids were detected with an amino acid analyzer. Moreover, alanine polymers were detected with LC-MS. Our research lights up a new pathway in the study of life’s origin.

  12. Radioiodinated 4-iodo-L-meta-tyrosine, a system L selective artificial amino acid: molecular design and transport characterization in Chinese hamster ovary cells (CHO-K1 cells)

    International Nuclear Information System (INIS)

    Introduction: High expression of the system L amino acid transporter has been observed in clinically important tissues including tumors and the blood-brain barrier. We examined amino acid transport system L selectivity of 14C(U)-L-tyrosine (14C-Tyr), 125I-4-iodo-L-meta-tyrosine (4-125I-mTyr), 125I-6-iodo-L-meta-tyrosine (6-125I-mTyr), 125I-3-iodo-α-methyl-L-tyrosine (125I-IMT) and 125I-3-iodo-L-tyrosine (3-125I-Tyr) using Chinese hamster ovary cells (CHO-K1). Methods: Cells in the exponential growth phase were incubated with 18.5 kBq of labeled amino acid in 2 mL of phosphate-buffered saline-based uptake solution and an uptake solution with/without Na+ at 37oC or 4oC. We examined the effects of the following compounds (1.0 mM) on transport: 2-(methylamino)isobutyric acid (a specific inhibitor of system A, in Na+-containing uptake solution); 2-amino-bicyclo[2,2,1]heptane-2-carboxylic acid (a specific inhibitor of system L, in Na+-free uptake solution); sodium azide and 2,4-dinitrophenol (NaN3 and DNP, inhibitors of the generation of adenosine triphosphate); p-aminohippurate and tetraethylammonium (PAH and TEA, inhibitors of organic anion and cation transporters); and L- and D-isomers of natural amino acids. Results: 14C-Tyr exhibited affinity for systems L, A and ASC. 4-125I-mTyr and 3-125I-Tyr exhibited high specificity for system L, whereas 6-125I-mTyr and 125I-IMT exhibited affinity for both systems L and ASC. Uptake of 4-125I-mTyr was markedly reduced by incubation at 4 oC, and was not significantly inhibited by NaN3, DNP, PAH or TEA. The inhibition profiles of the L- and D-isomers of natural amino acids indicated that system L mediates the transport of 4-125I-mTyr. Conclusions: 4-125I-mTyr exhibited the greatest system L specificity (93.46±0.13%) of all of the tested amino acids.

  13. Regulation of amino acid transporters in pluripotent cell populations in the embryo and in culture; novel roles for sodium-coupled neutral amino acid transporters.

    Science.gov (United States)

    Tan, Boon Siang Nicholas; Rathjen, Peter D; Harvey, Alexandra J; Gardner, David K; Rathjen, Joy

    2016-08-01

    The developmental outcomes of preimplantation mammalian embryos are regulated directly by the surrounding microenvironment, and inappropriate concentrations of amino acids, or the loss of amino acid-sensing mechanisms, can be detrimental and impact further development. A specific role for l-proline in the differentiation of embryonic stem (ES) cells, a cell population derived from the blastocyst, has been shown in culture. l-proline acts as a signalling molecule, exerting its effects through cell uptake and subsequent metabolism. Uptake in ES cells occurs predominantly through the sodium-coupled neutral amino acid transporter 2, Slc38a2 (SNAT2). Dynamic expression of amino acid transporters has been shown in the early mammalian embryo, reflecting functional roles for amino acids in embryogenesis. The expression of SNAT2 and family member Slc38a1 (SNAT1) was determined in mouse embryos from the 2-cell stage through to the early post-implantation pre-gastrulation embryo. Key changes in expression were validated in cell culture models of development. Both transporters showed temporal dynamic expression patterns and changes in intracellular localisation as differentiation progressed. Changes in transporter expression likely reflect different amino acid requirements during development. Findings include the differential expression of SNAT1 in the inner and outer cells of the compacted morula and nuclear localisation of SNAT2 in the trophectoderm and placental lineages. Furthermore, SNAT2 expression was up-regulated in the epiblast prior to primitive ectoderm formation, an expression pattern consistent with a role for the transporter in later developmental decisions within the pluripotent lineage. We propose that the differential expression of SNAT2 in the epiblast provides evidence for an l-proline-mediated mechanism contributing to the regulation of embryonic development. PMID:27373508

  14. Human intestine luminal ACE2 and amino acid transporter expression increased by ACE-inhibitors.

    Science.gov (United States)

    Vuille-dit-Bille, Raphael N; Camargo, Simone M; Emmenegger, Luca; Sasse, Tom; Kummer, Eva; Jando, Julia; Hamie, Qeumars M; Meier, Chantal F; Hunziker, Schirin; Forras-Kaufmann, Zsofia; Kuyumcu, Sena; Fox, Mark; Schwizer, Werner; Fried, Michael; Lindenmeyer, Maja; Götze, Oliver; Verrey, François

    2015-04-01

    Sodium-dependent neutral amino acid transporter B(0)AT1 (SLC6A19) and imino acid (proline) transporter SIT1 (SLC6A20) are expressed at the luminal membrane of small intestine enterocytes and proximal tubule kidney cells where they exert key functions for amino acid (re)absorption as documented by their role in Hartnup disorder and iminoglycinuria, respectively. Expression of B(0)AT1 was shown in rodent intestine to depend on the presence of the carboxypeptidase angiotensin-converting enzyme 2 (ACE2). This enzyme belongs to the renin-angiotensin system and its expression is induced by treatment with ACE-inhibitors (ACEIs) or angiotensin II AT1 receptor blockers (ARBs) in many rodent tissues. We show here in the Xenopus laevis oocyte expression system that human ACE2 also functionally interacts with SIT1. To investigate in human intestine the potential effect of ACEIs or ARBs on ACE2, we analysed intestinal biopsies taken during routine gastroduodenoscopy and ileocolonoscopy from 46 patients of which 9 were under ACEI and 13 ARB treatment. Analysis of transcript expression by real-time PCR and of proteins by immunofluorescence showed a co-localization of SIT1 and B(0)AT1 with ACE2 in the brush-border membrane of human small intestine enterocytes and a distinct axial expression pattern of the tested gene products along the intestine. Patients treated with ACEIs displayed in comparison with untreated controls increased intestinal mRNA levels of ACE2, peptide transporter PEPT1 (SLC15A1) and AA transporters B(0)AT1 and PAT1 (SLC36A1). This study unravels in human intestine the localization and distribution of intestinal transporters involved in amino acid absorption and suggests that ACEIs impact on their expression.

  15. Proton-dependent glutamine uptake by aphid bacteriocyte amino acid transporter ApGLNT1.

    Science.gov (United States)

    Price, Daniel R G; Wilson, Alex C C; Luetje, Charles W

    2015-10-01

    Aphids house large populations of the gammaproteobacterial symbiont Buchnera aphidicola in specialized bacteriocyte cells. The combined biosynthetic capability of the holobiont (Acyrthosiphon pisum and Buchnera) is sufficient for biosynthesis of all twenty protein coding amino acids, including amino acids that animals alone cannot synthesize; and that are present at low concentrations in A. pisum's plant phloem sap diet. Collaborative holobiont amino acid biosynthesis depends on glutamine import into bacteriocytes, which serves as a nitrogen-rich amino donor for biosynthesis of other amino acids. Recently, we characterized A. pisum glutamine transporter 1 (ApGLNT1), a member of the amino acid/auxin permease family, as the dominant bacteriocyte plasma membrane glutamine transporter. Here we show ApGLNT1 to be structurally and functionally related to mammalian proton-dependent amino acid transporters (PATs 1-4). Using functional expression in Xenopus laevis oocytes, combined with two-electrode voltage clamp electrophysiology we demonstrate that ApGLNT1 is electrogenic and that glutamine induces large inward currents. ApGLNT1 glutamine induced currents are dependent on external glutamine concentration, proton (H+) gradient across the membrane, and membrane potential. Based on these transport properties, ApGLNT1-mediated glutamine uptake into A. pisum bacteriocytes can be regulated by changes in either proton gradients across the plasma membrane or membrane potential. PMID:26028424

  16. Characterization and Regulation of the Amino Acid Transporter SNAT2 in the Small Intestine of Piglets.

    Science.gov (United States)

    Li, Guangran; Li, Jianjun; Tan, Bie; Wang, Jing; Kong, Xiangfeng; Guan, Guiping; Li, Fengna; Yin, Yulong

    2015-01-01

    The sodium-dependent neutral amino acid transporter 2 (SNAT2), which has dual transport/receptor functions, is well documented in eukaryotes and some mammalian systems, but has not yet been verified in piglets. The objective of this study was to investigate the characteristics and regulation of SNAT2 in the small intestine of piglets. The 1,521-bp porcine full cDNA sequence of SNAT2 (KC769999) from the small intestine of piglets was cloned. The open reading frame of cDNA encodes 506 deduced amino acid residues with a calculated molecular mass of 56.08 kDa and an isoelectric point (pI) of 7.16. Sequence alignment and phylogenetic analysis revealed that SNAT2 is highly evolutionarily conserved in mammals. SNAT2 mRNA can be detected in the duodenum, jejunum and ileum by real-time quantitative PCR. During the suckling period from days 1 to 21, the duodenum had the highest abundance of SNAT2 mRNA among the three segments of the small intestine. There was a significant decrease in the expression of SNAT2 mRNA in the duodenal and jejunal mucosa and in the expression of SNAT2 protein in the jejunal and ileal mucosa on day 1 after weaning (P absorption of amino acids and signal transduction in the porcine small intestine.

  17. Computational modelling of placental amino acid transfer as an integrated system.

    Science.gov (United States)

    Panitchob, N; Widdows, K L; Crocker, I P; Johnstone, E D; Please, C P; Sibley, C P; Glazier, J D; Lewis, R M; Sengers, B G

    2016-07-01

    Placental amino acid transfer is essential for fetal development and its impairment is associated with poor fetal growth. Amino acid transfer is mediated by a broad array of specific plasma membrane transporters with overlapping substrate specificity. However, it is not fully understood how these different transporters work together to mediate net flux across the placenta. Therefore the aim of this study was to develop a new computational model to describe how human placental amino acid transfer functions as an integrated system. Amino acid transfer from mother to fetus requires transport across the two plasma membranes of the placental syncytiotrophoblast, each of which contains a distinct complement of transporter proteins. A compartmental modelling approach was combined with a carrier based modelling framework to represent the kinetics of the individual accumulative, exchange and facilitative classes of transporters on each plasma membrane. The model successfully captured the principal features of transplacental transfer. Modelling results clearly demonstrate how modulating transporter activity and conditions such as phenylketonuria, can increase the transfer of certain groups of amino acids, but that this comes at the cost of decreasing the transfer of others, which has implications for developing clinical treatment options in the placenta and other transporting epithelia. PMID:27045077

  18. Characterization and Regulation of the Amino Acid Transporter SNAT2 in the Small Intestine of Piglets.

    Directory of Open Access Journals (Sweden)

    Guangran Li

    Full Text Available The sodium-dependent neutral amino acid transporter 2 (SNAT2, which has dual transport/receptor functions, is well documented in eukaryotes and some mammalian systems, but has not yet been verified in piglets. The objective of this study was to investigate the characteristics and regulation of SNAT2 in the small intestine of piglets. The 1,521-bp porcine full cDNA sequence of SNAT2 (KC769999 from the small intestine of piglets was cloned. The open reading frame of cDNA encodes 506 deduced amino acid residues with a calculated molecular mass of 56.08 kDa and an isoelectric point (pI of 7.16. Sequence alignment and phylogenetic analysis revealed that SNAT2 is highly evolutionarily conserved in mammals. SNAT2 mRNA can be detected in the duodenum, jejunum and ileum by real-time quantitative PCR. During the suckling period from days 1 to 21, the duodenum had the highest abundance of SNAT2 mRNA among the three segments of the small intestine. There was a significant decrease in the expression of SNAT2 mRNA in the duodenal and jejunal mucosa and in the expression of SNAT2 protein in the jejunal and ileal mucosa on day 1 after weaning (P < 0.05. Studies with enterocytes in vitro showed that amino acid starvation and supplementation with glutamate, arginine or leucine enhanced, while supplementation with glutamine reduced, SNAT2 mRNA expression (P < 0.05. These results regarding the characteristics and regulation of SNAT2 should help to provide some information to further clarify its roles in the absorption of amino acids and signal transduction in the porcine small intestine.

  19. Prenatal testosterone-induced fetal growth restriction is associated with down-regulation of rat placental amino acid transport

    Directory of Open Access Journals (Sweden)

    Hankins Gary DV

    2011-08-01

    Full Text Available Abstract Background Exposure of pregnant mothers to elevated concentrations of circulating testosterone levels is associated with fetal growth restriction and delivery of small-for-gestational-age babies. We examined whether maternal testosterone crosses the placenta to directly suppress fetal growth or if it modifies placental function to reduce the capacity for transport of nutrients to the fetus. Methods Pregnant rats were exposed to testosterone propionate (TP; 0.5 mg/kg by daily subcutaneous injection from gestational days (GD 15-19. Maternal and fetal testosterone levels, placental nutrient transport activity and expression of transporters and birth weight of pups and their anogenital distances were determined. Results This dose of TP doubled maternal testosterone levels but had no effect on fetal testosterone levels. Maternal daily weight gain was significantly lower only on GD 19 in TP treated dams compared to controls. Placental weight and birth weight of pups were significantly reduced, but the anogenital distance of pups were unaffected by TP treatment. Maternal plasma amino acids concentrations were altered following testosterone exposure, with decreases in glutamine, glycine, tyrosine, serine, proline, and hydroxyproline and increases in asparagine, isoleucine, leucine, lysine, histidine and arginine. In the TP dams, placental system A amino acid transport activity was significantly reduced while placental glucose transport capacity was unaffected. Decreased expression of mRNA and protein levels of slc38a2/Snat2, an amino acid transporter, suggests that reduced transporter proteins may be responsible for the decrease in amino acid transport activity. Conclusions Taken together, these data suggest that increased maternal testosterone concentrations do not cross the placenta to directly suppress fetal growth but affects amino acid nutrient delivery to the fetus by downregulating specific amino acid transporter activity.

  20. The D-amino acid transport by the invertebrate SLC6 transporters KAAT1 and CAATCH1 from Manduca sexta.

    Science.gov (United States)

    Vollero, Alessandra; Imperiali, Francesca G; Cinquetti, Raffaella; Margheritis, Eleonora; Peres, Antonio; Bossi, Elena

    2016-02-01

    The ability of the SLC6 family members, the insect neutral amino acid cotransporter KAAT1(K(+)-coupled amino acid transporter 1) and its homologous CAATCH1(cation anion activated amino acid transporter/channel), to transport D-amino acids has been investigated through heterologous expression in Xenopus laevis oocytes and electrophysiological techniques. In the presence of D-isomers of leucine, serine, and proline, the msKAAT1 generates inward, transport-associated, currents with variable relative potencies, depending on the driving ion Na(+) or K(+). Higher concentrations of D-leucine (≥1 mmol/L) give rise to an anomalous response that suggests the existence of a second binding site with inhibitory action on the transport process. msCAATCH1 is also able to transport the D-amino acids tested, including D-leucine, whereas L-leucine acts as a blocker. A similar behavior is exhibited by the KAAT1 mutant S308T, confirming the relevance of the residue in this position in L-leucine binding and the different interaction of D-leucine with residues involved in transport mechanism. D-leucine and D-serine on various vertebrate orthologs B(0)AT1 (SLC6A19) elicited only a very small current and singular behavior was not observed, indicating that it is specific of the insect neutral amino acid transporters. These findings highlight the relevance of D-amino acid absorption in the insect nutrition and metabolism and may provide new evidences in the molecular transport mechanism of SLC6 family. PMID:26884475

  1. Human L-type amino acid transporter 1 (LAT1): characterization of function and expression in tumor cell lines.

    Science.gov (United States)

    Yanagida, O; Kanai, Y; Chairoungdua, A; Kim, D K; Segawa, H; Nii, T; Cha, S H; Matsuo, H; Fukushima, J; Fukasawa, Y; Tani, Y; Taketani, Y; Uchino, H; Kim, J Y; Inatomi, J; Okayasu, I; Miyamoto, K; Takeda, E; Goya, T; Endou, H

    2001-10-01

    System L is a major nutrient transport system responsible for the transport of large neutral amino acids including several essential amino acids. We previously identified a transporter (L-type amino acid transporter 1: LAT1) subserving system L in C6 rat glioma cells and demonstrated that LAT1 requires 4F2 heavy chain (4F2hc) for its functional expression. Since its oncofetal expression was suggested in the rat liver, it has been proposed that LAT1 plays a critical role in cell growth and proliferation. In the present study, we have examined the function of human LAT1 (hLAT1) and its expression in human tissues and tumor cell lines. When expressed in Xenopus oocytes with human 4F2hc (h4F2hc), hLAT1 transports large neutral amino acids with high affinity (K(m)= approximately 15- approximately 50 microM) and L-glutamine and L-asparagine with low affinity (K(m)= approximately 1.5- approximately 2 mM). hLAT1 also transports D-amino acids such as D-leucine and D-phenylalanine. In addition, we show that hLAT1 accepts an amino acid-related anti-cancer agent melphalan. When loaded intracellularly, L-leucine and L-glutamine but not L-alanine are effluxed by extracellular substrates, confirming that hLAT1 mediates an amino acid exchange. hLAT1 mRNA is highly expressed in the human fetal liver, bone marrow, placenta, testis and brain. We have found that, while all the tumor cell lines examined express hLAT1 messages, the expression of h4F2hc is varied particularly in leukemia cell lines. In Western blot analysis, hLAT1 and h4F2hc have been confirmed to be linked to each other via a disulfide bond in T24 human bladder carcinoma cells. Finally, in in vitro translation, we show that hLAT1 is not a glycosylated protein even though an N-glycosylation site has been predicted in its extracellular loop, consistent with the property of the classical 4F2 light chain. The properties of the hLAT1/h4F2hc complex would support the roles of this transporter in providing cells with essential

  2. Aminoaciduria and altered renal expression of luminal amino acid transporters in mice lacking novel gene collectrin.

    Science.gov (United States)

    Malakauskas, Sandra M; Quan, Hui; Fields, Timothy A; McCall, Shannon J; Yu, Ming-Jiun; Kourany, Wissam M; Frey, Campbell W; Le, Thu H

    2007-02-01

    Defects in renal proximal tubule transport manifest in a number of human diseases. Although variable in clinical presentation, disorders such as Hartnup disease, Dent's disease, and Fanconi syndrome are characterized by wasting of solutes commonly recovered by the proximal tubule. One common feature of these disorders is aminoaciduria. There are distinct classes of amino acid transporters located in the apical and basal membranes of the proximal tubules that reabsorb >95% of filtered amino acids, yet few details are known about their regulation. We present our physiological characterization of a mouse line with targeted deletion of the gene collectrin that is highly expressed in the kidney. Collectrin-deficient mice display a reduced urinary concentrating capacity due to enhanced solute clearance resulting from profound aminoaciduria. The aminoaciduria is generalized, characterized by loss of nearly every amino acid, and results in marked crystalluria. Furthermore, in the kidney, collectrin-deficient mice have decreased plasma membrane populations of amino acid transporter subtypes B(0)AT1, rBAT, and b(0,+)AT, as well as altered cellular distribution of EAAC1. Our data suggest that collectrin is a novel mediator of renal amino acid transport and may provide further insight into the pathogenesis of a number of human disease correlates. PMID:16985211

  3. A new structural class of subtype-selective inhibitor of cloned excitatory amino acid transporter, EAAT2

    DEFF Research Database (Denmark)

    Bräuner-Osborne, Hans; Hermit, M B; Nielsen, B;

    2000-01-01

    We have studied the pharmacological effects of (RS)-2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propionic acid (AMPA) and the enantiomers of (RS)-2-amino-3-(3-hydroxy-1,2, 5-thiadiazol-4-yl)propionic acid (TDPA) on cloned human excitatory amino acid transporter subtypes 1, 2 and 3 (EAAT1-3) expres...

  4. Increased Rat Placental Fatty Acid, but Decreased Amino Acid and Glucose Transporters Potentially Modify Intrauterine Programming.

    Science.gov (United States)

    Nüsken, Eva; Gellhaus, Alexandra; Kühnel, Elisabeth; Swoboda, Isabelle; Wohlfarth, Maria; Vohlen, Christina; Schneider, Holm; Dötsch, Jörg; Nüsken, Kai-Dietrich

    2016-07-01

    Regulation of placental nutrient transport significantly affects fetal development and may modify intrauterine growth restriction (IUGR) and fetal programming. We hypothesized that placental nutrient transporters are differentially affected both by utero-placental insufficiency and prenatal surgical stress. Pregnant rats underwent bilateral uterine artery and vein ligation (LIG), sham operation (SOP) or no operation (controls, C) on gestational day E19. Placentas were obtained by caesarean section 4 h (LIG, n=20 placentas; SOP, n=24; C, n=12), 24 h (LIG, n=28; SOP, n=20; C, n=12) and 72 h (LIG, n=20; SOP, n=20; C, n=24) after surgery. Gene and protein expression of placental nutrient transporters for fatty acids (h-FABP, CD36), amino acids (SNAT1, SNAT2) and glucose (GLUT-1, Connexin 26) were examined by qRT-PCR, western blot and immunohistochemistry. Interestingly, the mean protein expression of h-FABP was doubled in placentas of LIG and SOP animals 4, 24 (SOP significant) and 72 h (SOP significant) after surgery. CD36 protein was significantly increased in LIG after 72 h. SNAT1 and SNAT2 protein and gene expressions were significantly reduced in LIG and SOP after 24 h. Further significantly reduced proteins were GLUT-1 in LIG (4 h, 72 h) and SOP (24 h), and Connexin 26 in LIG (72 h). In conclusion, placental nutrient transporters are differentially affected both by reduced blood flow and stress, probably modifying the already disturbed intrauterine milieu and contributing to IUGR and fetal programming. Increased fatty acid transport capacity may affect energy metabolism and could be a compensatory reaction with positive effects on brain development. J. Cell. Biochem. 117: 1594-1603, 2016. © 2015 Wiley Periodicals, Inc. PMID:26590355

  5. Third generation capture system: precipitating amino acid solvent systems

    NARCIS (Netherlands)

    Sanchez Fernandez, E.; Misiak, K.; Ham, L. van der; Goetheer, E.L.V.

    2013-01-01

    This work summarises the results of the design of novel separation processes for CO2 removal from flue gas based on precipitating amino acid solvents. The processes here described (DECAB, DECAB Plus and pH-swing) use a combination of enhanced CO2 absorption (based on the Le Chatelier’s principle) an

  6. Circumvention of defective neutral amino acid transport in Hartnup disease using tryptophan ethyl ester.

    OpenAIRE

    Jonas, A J; Butler, I J

    1989-01-01

    Tryptophan ethyl ester, a lipid-soluble tryptophan derivative, was used to bypass defective gastrointestinal neutral amino acid transport in a child with Hartnup disease. The child's baseline tryptophan concentrations in serum (20 +/- 6 microM) and cerebrospinal fluid (1.0 +/- 0.2 microM) were persistently less than 50% of normal values. Cerebrospinal fluid 5-hydroxyindoleacetic acid (5-HIAA), a serotonin metabolite, was also less than 50% of normal (21 +/- 2 ng/ml). Serum tryptophan concentr...

  7. The importance of the excitatory amino acid transporter 3 (EAAT3)

    DEFF Research Database (Denmark)

    E. Bjørn-Yoshimoto, Walden; Underhill, Suzanne M.

    2016-01-01

    Abstract The neuronal excitatory amino acid transporter 3 (EAAT3) is fairly ubiquitously expressed in the brain, though it does not necessarily maintain the same function everywhere. It is important in maintaining low local concentrations of glutamate, where its predominant post-synaptic localiza......Abstract The neuronal excitatory amino acid transporter 3 (EAAT3) is fairly ubiquitously expressed in the brain, though it does not necessarily maintain the same function everywhere. It is important in maintaining low local concentrations of glutamate, where its predominant post...... neurons, it is important in supplying glutamate as a precursor for GABA synthesis. Several diseases implicate EAAT3, and modulation of this transporter could prove a useful therapeutic approach. Regulation of EAAT3 could be targeted at several points for functional modulation, including the level...

  8. Stimulation of the amino acid transporter SLC6A19 by JAK2

    Energy Technology Data Exchange (ETDEWEB)

    Bhavsar, Shefalee K.; Hosseinzadeh, Zohreh; Merches, Katja; Gu, Shuchen [Department of Physiology I, University of Tuebingen (Germany); Broeer, Stefan [Research School of Biology, Australian National University (Australia); Lang, Florian, E-mail: florian.lang@uni-tuebingen.de [Department of Physiology I, University of Tuebingen (Germany)

    2011-10-28

    Highlights: Black-Right-Pointing-Pointer The amino acid transporter SLC6A19 is upregulated by Janus kinase-2 JAK2. Black-Right-Pointing-Pointer The {sup V617F}JAK2 mutant, causing myeloproliferative disease, is more effective. Black-Right-Pointing-Pointer JAK2 inhibitor AG490 reverses stimulation of SLC6A19 by {sup V617F}JAK2. Black-Right-Pointing-Pointer JAK2 enhances SLC6A19 protein insertion into the cell membrane. Black-Right-Pointing-Pointer SLC6A19 may contribute to amino acid uptake into {sup V617F}JAK2 expressing tumor cells. -- Abstract: JAK2 (Janus kinase-2) is expressed in a wide variety of cells including tumor cells and contributes to the proliferation and survival of those cells. The gain of function mutation {sup V617F}JAK2 mutant is found in the majority of myeloproliferative diseases. Cell proliferation depends on the availability of amino acids. Concentrative cellular amino acid uptake is in part accomplished by Na{sup +} coupled amino acid transport through SLC6A19 (B(0)AT). The present study thus explored whether JAK2 activates SLC6A19. To this end, SLC6A19 was expressed in Xenopus oocytes with or without wild type JAK2, {sup V617F}JAK2 or inactive {sup K882E}JAK2 and electrogenic amino acid transport determined by dual electrode voltage clamp. In SLC6A19-expressing oocytes but not in oocytes injected with water or JAK2 alone, the addition of leucine (2 mM) to the bath generated a current (I{sub le}), which was significantly increased following coexpression of JAK2 or {sup V617F}JAK2, but not by coexpression of {sup K882E}JAK2. Coexpression of JAK2 enhanced the maximal transport rate without significantly modifying the affinity of the carrier. Exposure of the oocytes to the JAK2 inhibitor AG490 (40 {mu}M) resulted in a gradual decline of I{sub le}. According to chemiluminescence JAK2 enhanced the carrier protein abundance in the cell membrane. The decline of I{sub le} following inhibition of carrier insertion by brefeldin A (5 {mu}M) was similar

  9. Expression of apical Na(+)-L-glutamine co-transport activity, B(0)-system neutral amino acid co-transporter (B(0)AT1) and angiotensin-converting enzyme 2 along the jejunal crypt-villus axis in young pigs fed a liquid formula

    Science.gov (United States)

    Gut apical amino acid (AA) transport activity is high at birth and during suckling, thus being essential to maintain luminal nutrient-dependent mucosal growth through providing AA as essential metabolic fuel, substrates and nutrient stimuli for cellular growth. Because system-B(0) Na(+)-neutral AA c...

  10. Regulation of amino acid transporter trafficking by mTORC1 in primary human trophoblast cells is mediated by the ubiquitin ligase Nedd4-2.

    Science.gov (United States)

    Rosario, Fredrick J; Dimasuay, Kris Genelyn; Kanai, Yoshikatsu; Powell, Theresa L; Jansson, Thomas

    2016-04-01

    Changes in placental amino acid transfer directly contribute to altered fetal growth, which increases the risk for perinatal complications and predisposes for the development of obesity, diabetes and cardiovascular disease later in life. Placental amino acid transfer is critically dependent on the expression of specific transporters in the plasma membrane of the trophoblast, the transporting epithelium of the human placenta. However, the molecular mechanisms regulating this process are largely unknown. Nedd4-2 is an ubiquitin ligase that catalyses the ubiquitination of proteins, resulting in proteasomal degradation. We hypothesized that inhibition of mechanistic target of rapamycin complex 1 (mTORC1) decreases amino acid uptake in primary human trophoblast (PHT) cells by activation of Nedd4-2, which increases transporter ubiquitination resulting in decreased transporter expression in the plasma membrane. mTORC 1 inhibition increased the expression of Nedd4-2, promoted ubiquitination and decreased the plasma membrane expression of SNAT2 (an isoform of the System A amino acid transporter) and LAT1 (a System L amino acid transporter isoform), resulting in decreased cellular amino acid uptake. Nedd4-2 silencing markedly increased the trafficking of SNAT2 and LAT1 to the plasma membrane, which stimulated cellular amino acid uptake. mTORC1 inhibition by silencing of raptor failed to decrease amino acid transport following Nedd4-2 silencing. In conclusion, we have identified a novel link between mTORC1 signalling and ubiquitination, a common posttranslational modification. Because placental mTORC1 is inhibited in fetal growth restriction and activated in fetal overgrowth, we propose that regulation of placental amino acid transporter ubiquitination by mTORC1 and Nedd4-2 constitutes a molecular mechanisms underlying abnormal fetal growth.

  11. Imaging the L-type amino acid transporter-1 (LAT1 with Zr-89 immunoPET.

    Directory of Open Access Journals (Sweden)

    Oluwatayo F Ikotun

    Full Text Available The L-type amino acid transporter-1 (LAT1, SLC7A5 is upregulated in a wide range of human cancers, positively correlated with the biological aggressiveness of tumors, and a promising target for both imaging and therapy. Radiolabeled amino acids such as O-(2-[(18F]fluoroethyl-L-tyrosine (FET that are transport substrates for system L amino acid transporters including LAT1 have met limited success for oncologic imaging outside of the brain, and thus new strategies are needed for imaging LAT1 in systemic cancers. Here, we describe the development and biological evaluation of a novel zirconium-89 labeled antibody, [(89Zr]DFO-Ab2, targeting the extracellular domain of LAT1 in a preclinical model of colorectal cancer. This tracer demonstrated specificity for LAT1 in vitro and in vivo with excellent tumor imaging properties in mice with xenograft tumors. PET imaging studies showed high tumor uptake, with optimal tumor-to-non target contrast achieved at 7 days post administration. Biodistribution studies demonstrated tumor uptake of 10.5 ± 1.8 percent injected dose per gram (%ID/g at 7 days with a tumor to muscle ratio of 13 to 1. In contrast, the peak tumor uptake of the radiolabeled amino acid [(18F]FET was 4.4 ± 0.5 %ID/g at 30 min after injection with a tumor to muscle ratio of 1.4 to 1. Blocking studies with unlabeled anti-LAT1 antibody demonstrated a 55% reduction of [(89Zr]DFO-Ab2 accumulation in the tumor at 7 days. These results are the first report of direct PET imaging of LAT1 and demonstrate the potential of immunoPET agents for imaging specific amino acid transporters.

  12. Dietary amino acid-induced systemic lupus erythematosus.

    Science.gov (United States)

    Montanaro, A; Bardana, E J

    1991-05-01

    The effects of dietary manipulations on autoimmune disease are understood poorly. In this article, we detail our experience with a human subject who developed autoimmune hemolytic anemia while participating in a research study that required the ingestion of alfalfa seeds. Subsequent experimental studies in primates ingesting alfalfa sprout seeds and L-canavanine (a prominent amino acid constituent of alfalfa) is presented. The results of these studies indicate a potential toxic and immunoregulatory role of L-canavanine in the induction of a systemic lupus-like disease in primates. PMID:1862241

  13. Evidence for transport intermediates in aromatic amino acid synthesis of non-green tissues

    International Nuclear Information System (INIS)

    Quinate (QA) is the predominant pre-aromatic compound formed at high rates in leaves of many plants at the early vegetation stage and transported through the phloem. The transfer of 3-dehydroquinate, 3-dehydroshikimate and (SkA) across the plastidial membranes has been evidenced. The question was whether the rate of QA uptake is comparable to that of the 3 SkA-pathway intermediates. To demonstrate this, /U-14C/QA and /U-14C/SkA were applied to Brassica rapa roots. Both compounds were uptaken at considerable rates and incorporated into aromatic amino acids (Phe + Tyr + Trp formation, in nmol/g fresh wt x h: applying 145 μmol QA: 21.2; applying 156 μmol Ska: 31.8). Thus, QA is a possible candidate for transport into non-green tissues for aromatic amino acid synthesis

  14. Evidence for transport intermediates in aromatic amino acid synthesis of non-green tissues

    Energy Technology Data Exchange (ETDEWEB)

    Leuschner, C.; Schultz, G. (Botanisches Institut, Hannover (West Germany))

    1990-05-01

    Quinate (QA) is the predominant pre-aromatic compound formed at high rates in leaves of many plants at the early vegetation stage and transported through the phloem. The transfer of 3-dehydroquinate, 3-dehydroshikimate and (SkA) across the plastidial membranes has been evidenced. The question was whether the rate of QA uptake is comparable to that of the 3 SkA-pathway intermediates. To demonstrate this, /U-{sup 14}C/QA and /U-{sup 14}C/SkA were applied to Brassica rapa roots. Both compounds were uptaken at considerable rates and incorporated into aromatic amino acids (Phe + Tyr + Trp formation, in nmol/g fresh wt x h: applying 145 {mu}mol QA: 21.2; applying 156 {mu}mol Ska: 31.8). Thus, QA is a possible candidate for transport into non-green tissues for aromatic amino acid synthesis.

  15. Accumulation, selection and covariation of amino acids in sieve tube sap of tansy (Tanacetum vulgare) and castor bean (Ricinus communis): evidence for the function of a basic amino acid transporter and the absence of a γ-amino butyric acid transporter.

    Science.gov (United States)

    Bauer, Susanne N; Nowak, Heike; Keller, Frank; Kallarackal, Jose; Hajirezaei, Mohamad-Reza; Komor, Ewald

    2014-09-01

    Sieve tube sap was obtained from Tanacetum by aphid stylectomy and from Ricinus after apical bud decapitation. The amino acids in sieve tube sap were analyzed and compared with those from leaves. Arginine and lysine accumulated in the sieve tube sap of Tanacetum more than 10-fold compared to the leaf extracts and they were, together with asparagine and serine, preferably selected into the sieve tube sap, whereas glycine, methionine/tryptophan and γ-amino butyric acid were partially or completely excluded. The two basic amino acids also showed a close covariation in sieve tube sap. The acidic amino acids also grouped together, but antagonistic to the other amino acids. The accumulation ratios between sieve tube sap and leaf extracts were smaller in Ricinus than in Tanacetum. Arginine, histidine, lysine and glutamine were enriched and preferentially loaded into the phloem, together with isoleucine and valine. In contrast, glycine and methionine/tryptophan were partially and γ-amino butyric acid almost completely excluded from sieve tube sap. The covariation analysis grouped arginine together with several neutral amino acids. The acidic amino acids were loaded under competition with neutral amino acids. It is concluded from comparison with the substrate specificities of already characterized plant amino acid transporters, that an AtCAT1-like transporter functions in phloem loading of basic amino acids, whereas a transporter like AtGAT1 is absent in phloem. Although Tanacetum and Ricinus have different minor vein architecture, their phloem loading specificities for amino acids are relatively similar. PMID:24446756

  16. Accumulation, selection and covariation of amino acids in sieve tube sap of tansy (Tanacetum vulgare) and castor bean (Ricinus communis): evidence for the function of a basic amino acid transporter and the absence of a γ-amino butyric acid transporter.

    Science.gov (United States)

    Bauer, Susanne N; Nowak, Heike; Keller, Frank; Kallarackal, Jose; Hajirezaei, Mohamad-Reza; Komor, Ewald

    2014-09-01

    Sieve tube sap was obtained from Tanacetum by aphid stylectomy and from Ricinus after apical bud decapitation. The amino acids in sieve tube sap were analyzed and compared with those from leaves. Arginine and lysine accumulated in the sieve tube sap of Tanacetum more than 10-fold compared to the leaf extracts and they were, together with asparagine and serine, preferably selected into the sieve tube sap, whereas glycine, methionine/tryptophan and γ-amino butyric acid were partially or completely excluded. The two basic amino acids also showed a close covariation in sieve tube sap. The acidic amino acids also grouped together, but antagonistic to the other amino acids. The accumulation ratios between sieve tube sap and leaf extracts were smaller in Ricinus than in Tanacetum. Arginine, histidine, lysine and glutamine were enriched and preferentially loaded into the phloem, together with isoleucine and valine. In contrast, glycine and methionine/tryptophan were partially and γ-amino butyric acid almost completely excluded from sieve tube sap. The covariation analysis grouped arginine together with several neutral amino acids. The acidic amino acids were loaded under competition with neutral amino acids. It is concluded from comparison with the substrate specificities of already characterized plant amino acid transporters, that an AtCAT1-like transporter functions in phloem loading of basic amino acids, whereas a transporter like AtGAT1 is absent in phloem. Although Tanacetum and Ricinus have different minor vein architecture, their phloem loading specificities for amino acids are relatively similar.

  17. Plasma amino acids

    Science.gov (United States)

    Amino acids blood test ... types of methods used to determine the individual amino acid levels in the blood. ... test is done to measure the level of amino acids in the blood. An increased level of a ...

  18. Pharmacokinetics of amino acid ester prodrugs of acyclovir after oral administration: interaction with the transporters on Caco-2 cells.

    Science.gov (United States)

    Katragadda, Suresh; Jain, Ritesh; Kwatra, Deep; Hariharan, Sudharshan; Mitra, Ashim K

    2008-10-01

    In vivo systemic absorption of the amino acid prodrugs of acyclovir (ACV) after oral administration was evaluated in rats. Stability of the prodrugs, L-alanine-ACV (AACV), L-serine-ACV (SACV), L-isoleucine-ACV (IACV), gamma-glutamate-ACV (EACV) and L-valine-ACV (VACV) was evaluated in various tissues. Interaction of these prodrugs with the transporters on Caco-2 cells was studied. In vivo systemic bioavailability of these prodrugs upon oral administration was evaluated in jugular vein cannulated rats. The amino acid ester prodrugs showed affinity towards various amino acid transporters as well as the peptide transporter on the Caco-2 cells. In terms of stability, EACV was most enzymatically stable compared to other prodrugs especially in liver homogenate. In oral absorption studies, ACV and AACV showed high terminal elimination rate constants (lambda(z)). SACV and VACV exhibited approximately five-fold increase in area under the curve (AUC) values relative to ACV (pACV. C(last(T)) (concentration at the last time point) of SACV was observed to be 0.18+/-0.06 microM in plasma which is two times better than VACV and three times better than ACV. Amino acid ester prodrugs of ACV were absorbed at varying amounts (C(max)) and eliminated at varying rates (lambda(z)) thereby leading to varying extents (AUC). The amino acid ester prodrug SACV owing to its enhanced stability, higher AUC and better concentration at last time point seems to be a promising candidate for the oral treatment of herpes infections.

  19. A single amino acid change converts the sugar sensor SGLT3 into a sugar transporter.

    Directory of Open Access Journals (Sweden)

    Laura Bianchi

    Full Text Available BACKGROUND: Sodium-glucose cotransporter proteins (SGLT belong to the SLC5A family, characterized by the cotransport of Na(+ with solute. SGLT1 is responsible for intestinal glucose absorption. Until recently the only role described for SGLT proteins was to transport sugar with Na(+. However, human SGLT3 (hSGLT3 does not transport sugar but causes depolarization of the plasma membrane when expressed in Xenopus oocytes. For this reason SGLT3 was suggested to be a sugar sensor rather than a transporter. Despite 70% amino acid identity between hSGLT3 and hSGLT1, their sugar transport, apparent sugar affinities, and sugar specificity differ greatly. Residue 457 is important for the function of SGLT1 and mutation at this position in hSGLT1 causes glucose-galactose malabsorption. Moreover, the crystal structure of vibrio SGLT reveals that the residue corresponding to 457 interacts directly with the sugar molecule. We thus wondered if this residue could account for some of the functional differences between SGLT1 and SGLT3. METHODOLOGY/PRINCIPAL FINDINGS: We mutated the glutamate at position 457 in hSGLT3 to glutamine, the amino acid present in all SGLT1 proteins, and characterized the mutant. Surprisingly, we found that E457Q-hSGLT3 transported sugar, had the same stoichiometry as SGLT1, and that the sugar specificity and apparent affinities for most sugars were similar to hSGLT1. We also show that SGLT3 functions as a sugar sensor in a living organism. We expressed hSGLT3 and E457Q-hSGLT3 in C. elegans sensory neurons and found that animals sensed glucose in an hSGLT3-dependent manner. CONCLUSIONS/SIGNIFICANCE: In summary, we demonstrate that hSGLT3 functions as a sugar sensor in vivo and that mutating a single amino acid converts this sugar sensor into a sugar transporter similar to SGLT1.

  20. Basic Amino Acid Transport in Plasma Membrane Vesicles of Penicillium chrysogenum

    NARCIS (Netherlands)

    Hillenga, Dirk J.; Versantvoort, Hanneke J.M.; Driessen, Arnold J.M.; Konings, Wil N.

    1996-01-01

    The characteristics of the basic amino acid permease (system VI) of the filamentous fungus Penicillium chrysogenum were studied in plasma membranes fused with liposomes containing the beef heart mitochondrial cytochrome c oxidase. In the presence of reduced cytochrome c, the hybrid membranes accumul

  1. Structural basis for amino acid export by DMT superfamily transporter YddG.

    Science.gov (United States)

    Tsuchiya, Hirotoshi; Doki, Shintaro; Takemoto, Mizuki; Ikuta, Tatsuya; Higuchi, Takashi; Fukui, Keita; Usuda, Yoshihiro; Tabuchi, Eri; Nagatoishi, Satoru; Tsumoto, Kouhei; Nishizawa, Tomohiro; Ito, Koichi; Dohmae, Naoshi; Ishitani, Ryuichiro; Nureki, Osamu

    2016-05-30

    The drug/metabolite transporter (DMT) superfamily is a large group of membrane transporters ubiquitously found in eukaryotes, bacteria and archaea, and includes exporters for a remarkably wide range of substrates, such as toxic compounds and metabolites. YddG is a bacterial DMT protein that expels aromatic amino acids and exogenous toxic compounds, thereby contributing to cellular homeostasis. Here we present structural and functional analyses of YddG. Using liposome-based analyses, we show that Escherichia coli and Starkeya novella YddG export various amino acids. The crystal structure of S. novella YddG at 2.4 Å resolution reveals a new membrane transporter topology, with ten transmembrane segments in an outward-facing state. The overall structure is basket-shaped, with a large substrate-binding cavity at the centre of the molecule, and is composed of inverted structural repeats related by two-fold pseudo-symmetry. On the basis of this intramolecular symmetry, we propose a structural model for the inward-facing state and a mechanism of the conformational change for substrate transport, which we confirmed by biochemical analyses. These findings provide a structural basis for the mechanism of transport of DMT superfamily proteins.

  2. Structural basis for amino acid export by DMT superfamily transporter YddG.

    Science.gov (United States)

    Tsuchiya, Hirotoshi; Doki, Shintaro; Takemoto, Mizuki; Ikuta, Tatsuya; Higuchi, Takashi; Fukui, Keita; Usuda, Yoshihiro; Tabuchi, Eri; Nagatoishi, Satoru; Tsumoto, Kouhei; Nishizawa, Tomohiro; Ito, Koichi; Dohmae, Naoshi; Ishitani, Ryuichiro; Nureki, Osamu

    2016-06-16

    The drug/metabolite transporter (DMT) superfamily is a large group of membrane transporters ubiquitously found in eukaryotes, bacteria and archaea, and includes exporters for a remarkably wide range of substrates, such as toxic compounds and metabolites. YddG is a bacterial DMT protein that expels aromatic amino acids and exogenous toxic compounds, thereby contributing to cellular homeostasis. Here we present structural and functional analyses of YddG. Using liposome-based analyses, we show that Escherichia coli and Starkeya novella YddG export various amino acids. The crystal structure of S. novella YddG at 2.4 Å resolution reveals a new membrane transporter topology, with ten transmembrane segments in an outward-facing state. The overall structure is basket-shaped, with a large substrate-binding cavity at the centre of the molecule, and is composed of inverted structural repeats related by two-fold pseudo-symmetry. On the basis of this intramolecular symmetry, we propose a structural model for the inward-facing state and a mechanism of the conformational change for substrate transport, which we confirmed by biochemical analyses. These findings provide a structural basis for the mechanism of transport of DMT superfamily proteins. PMID:27281193

  3. Plasma amino acids

    Science.gov (United States)

    Plasma amino acids is a screening test done on infants that looks at the amounts of amino ... Laboratory error High or low amounts of individual plasma amino acids must be considered with other information. ...

  4. Differences in the effect of ionizing radiation on NA+-dependent amino acid transport in human T (Molt-4) and human B (RPMI 1788) lymphoid cells

    International Nuclear Information System (INIS)

    We have investigated the effects of ionizing radiation (0.10 to 10 krad) on the Na+-dependent transport of 2-aminoisobutyric acid and the involvement of a plasma membrane sulfhydryl-protein component which modulates this transport system in a human T (Molt-4) and a B (RPMI 1788) lymphoid cell line. The radiosensitivity of this transport system and a putative sulfhydryl membrane regulatory component correlated with the known radiosensitivity of these two cell lines, i.e., DNA synthesis and survival, were much more sensitive to the effects of γ irradiation in Molt-4 than in RPMI 1788 cells. Ionizing radiation affected Na+-dependent amino acid transport in Molt-4 cells by a process which affects the maximal rate of uptake of the amino acid (i.e., V/sub max/) into the cell. No change in Na+-independent amino acid transport was observed when Molt-4 cells were subjected to radiation levels as high as 5 krad. These data coupled with the observations from other laboratories have led us to hypothesize that the radiation-induced interphase death of Molt-4 cells may be due to two factors: (i) damage to a plasma membrane sulfhydryl-protein component associated with the modulation of Na+-dependent transport of amino acids which are involved in DNA synthesis and (ii) damage to nuclear processes, which is enhanced when Na+-dependent amino acid transport is inhibited

  5. Potential Biomarker of L type Amino Acid Transporter 1 in Breast Cancer Progression

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Zhongxing; Cho, Heidi T.; Williams, Larry; Zhu, Aizhi; Liang, Ke; Huang, Ke; Wu, Hui; Jiang, Chunsu; Hong, Samuel; Crowe, Ronald; Goodman, Mark M.; Shim, Hyunsuk [Emory Univ. School of Medicine, Atlanta (United States)

    2011-06-15

    L type amino acid transporter 1 (LAT1) is essential for the transport of large neutral amino acids. However, its role in breast cancer growth remains largely unknown. The purpose of the study is to investigate whether LAT1 is a potential biomarker for the diagnosis and treatment of breast cancer. LAT1 mRNA and protein levels in breast cancer cell lines and tissues were analyzed. In addition, the effects of targeting LAT1 for the inhibition of breast cancer cell tumorigenesis were assessed with soft agar assay. The imaging of xenograft with 1 amino 3 [{sup 18F}]fluorocyclo butane 1 carboxylic acid ([{sup 18F}]FACBC) PET was assessed for its diagnostic biomarker potential. Normal breast tissue or low malignant cell lines expressed low levels of LAT1 mRNA and protein, while highly malignant cancer cell lines and high grade breast cancer tissue expressed high levels of LAT1. In addition, higher expression levels of LAT1 in breast cancer tissues were consistent with advanced stage breast cancer. Furtermore, the blockade of LAT1 with its inhibitor, 2 amino bicyclo[2.2.1]heptane 2 carboxylic acid (BCH), or the knockdown of LAT1 with siRNA, inhibited proliferation and tumorigenesis of breast cancer cells. A leucine analog, [{sup 18F}]FACBC, has been demonstrated to be an excellent PET tracer for the non invasive imaging og malignant breast cancer using an orthotopic animal model. The overexpression of LAT1 is required for the progression of breast cancer. LAT1 represents a potential biomarker for therapy and diagnosis of breast cancer. [{sup 18F}]FACBC that correlates with LAT1 function is a potential PET tracer for malignant breast tumor imaging.

  6. Expression of L amino acid transport system 1 and analysis of iodine-123-methyltyrosine tumor uptake in a pancreatic xenotransplantation model using fused high-resolution-micro-SPECT-MRI

    Institute of Scientific and Technical Information of China (English)

    Corinna von Forstner; Maaz Zuhayra; Ole Ammerpohl; Yi Zhao; Sanjay Tiwari; Olav Jansen; Holger Kalthoff; Eberhard Henze; Jan-Hendrik Egberts

    2011-01-01

    BACKGROUND: The specificity in discriminating pancreatitis is limited in the positron emission tomography (PET) using Fluorine-18-fluorodeoxyglucose.Furthermore,PETisnot widely available compared to the single photon emission computed tomography (SPECT). Since amino acids play a minor role in metabolism of inflammatory cells, the potential of the SPECT tracer, 3-[123I]iodo-L-α-methyltyrosine (123I-IMT), for detecting pancreatic cancer was examined in xenotransplantation models of humanpancreaticcarcinomainmice. METHODS:  123I-IMT was injected to eight mice inoculated with subcutaneous or orthotopic pancreatic tumors. Fused high-resolution-micro-SPECT (Hi-SPECT) and magnetic resonance imaging were performed. The gene expression level of L amino acid transport-system 1 (LAT1) was analyzed and correlated with tumor uptake of 123I-IMT. RESULTS: A high uptake of 123I-IMT was detected in all tumor-bearing mice. The median tumor-to-background ratio (T/B) was 12.1 (2.0-13.2) for orthotopic and 8.4 (1.8-11.1) for subcutaneous xenotransplantation, respectively. Accordingly, the LAT1 expression in transplanted Colo357 cells was increased compared to non-malignant controls. CONCLUSIONS: Our mouse model could show a high 123I-IMT uptake in pancreatic cancer. Fused MRI scans facilitate precise evaluation of uptake in the specific regions of interest. Further studies are required to confirm these findings in tumors derived from other human pancreatic cancer cells. Since amino acids play a minor role in the metabolism of inflammatory cells, the potential for application of 123I-IMT to distinguish pancreatic tumor from inflammatory pancreatitis warrants further investigation.

  7. Changes in the amino acid composition of buffalo milk after chemical activation of its lactoperoxidase system

    Directory of Open Access Journals (Sweden)

    M. Tsankova

    2010-02-01

    Full Text Available The amino acid content of bulked buffalo milk, collected from 130 buffaloes reared at a buffalo farm in the settlement of Dimitrievo, Stara Zagora region, was investigated during the period January-April 2006. The activation of the lactoperoxidase system (LPS was done by supplementation of sodium percarbonate, providing 16 ppm active oxygen and 10 ppm thiocyanate to 1 l of milk. The amino acid content was assayed by an amino acid analyzer. It was found out that the total content of amino acids in inactivated milk was insignificantly lower than that in activated one. More considerable increase was established for the amino acids valine, methionine, and lysine, but the differences were not statistically significant. The total amount of essential amino acids was higher in the milk with chemically activated LPS. The limiting essential amino acid in the studied buffalo milk was methionine.

  8. Protein Restriction with Amino Acid-Balanced Diets Shrinks Circulating Pool Size of Amino Acid by Decreasing Expression of Specific Transporters in the Small Intestine.

    Science.gov (United States)

    Qiu, Kai; Qin, Chun Fu; Luo, Min; Zhang, Xin; Sun, Wen Juan; Jiao, Ning; Li, De Fa; Yin, Jing Dong

    2016-01-01

    Dietary protein restriction is not only beneficial to health and longevity in humans, but also protects against air pollution and minimizes feeding cost in livestock production. However, its impact on amino acid (AA) absorption and metabolism is not quite understood. Therefore, the study aimed to explore the effect of protein restriction on nitrogen balance, circulating AA pool size, and AA absorption using a pig model. In Exp.1, 72 gilts weighting 29.9 ± 1.5 kg were allocated to 1 of the 3 diets containing 14, 16, or 18% CP for a 28-d trial. Growth (n = 24), nitrogen balance (n = 6), and the expression of small intestinal AA and peptide transporters (n = 6) were evaluated. In Exp.2, 12 barrows weighting 22.7 ± 1.3 kg were surgically fitted with catheters in the portal and jejunal veins as well as the carotid artery and assigned to a diet containing 14 or 18% CP. A series of blood samples were collected before and after feeding for determining the pool size of circulating AA and AA absorption in the portal vein, respectively. Protein restriction did not sacrifice body weight gain and protein retention, since nitrogen digestibility was increased as dietary protein content reduced. However, the pool size of circulating AA except for lysine and threonine, and most AA flux through the portal vein were reduced in pigs fed the low protein diet. Meanwhile, the expression of peptide transporter 1 (PepT-1) was stimulated, but the expression of the neutral and cationic AA transporter systems was depressed. These results evidenced that protein restriction with essential AA-balanced diets, decreased AA absorption and reduced circulating AA pool size. Increased expression of small intestinal peptide transporter PepT-1 could not compensate for the depressed expression of jejunal AA transporters for AA absorption.

  9. Protein Restriction with Amino Acid-Balanced Diets Shrinks Circulating Pool Size of Amino Acid by Decreasing Expression of Specific Transporters in the Small Intestine

    Science.gov (United States)

    Luo, Min; Zhang, Xin; Sun, Wen Juan; Jiao, Ning; Li, De Fa; Yin, Jing Dong

    2016-01-01

    Dietary protein restriction is not only beneficial to health and longevity in humans, but also protects against air pollution and minimizes feeding cost in livestock production. However, its impact on amino acid (AA) absorption and metabolism is not quite understood. Therefore, the study aimed to explore the effect of protein restriction on nitrogen balance, circulating AA pool size, and AA absorption using a pig model. In Exp.1, 72 gilts weighting 29.9 ± 1.5 kg were allocated to 1 of the 3 diets containing 14, 16, or 18% CP for a 28-d trial. Growth (n = 24), nitrogen balance (n = 6), and the expression of small intestinal AA and peptide transporters (n = 6) were evaluated. In Exp.2, 12 barrows weighting 22.7 ± 1.3 kg were surgically fitted with catheters in the portal and jejunal veins as well as the carotid artery and assigned to a diet containing 14 or 18% CP. A series of blood samples were collected before and after feeding for determining the pool size of circulating AA and AA absorption in the portal vein, respectively. Protein restriction did not sacrifice body weight gain and protein retention, since nitrogen digestibility was increased as dietary protein content reduced. However, the pool size of circulating AA except for lysine and threonine, and most AA flux through the portal vein were reduced in pigs fed the low protein diet. Meanwhile, the expression of peptide transporter 1 (PepT-1) was stimulated, but the expression of the neutral and cationic AA transporter systems was depressed. These results evidenced that protein restriction with essential AA-balanced diets, decreased AA absorption and reduced circulating AA pool size. Increased expression of small intestinal peptide transporter PepT-1 could not compensate for the depressed expression of jejunal AA transporters for AA absorption. PMID:27611307

  10. Cationic amino acid transporter 2 enhances innate immunity during Helicobacter pylori infection.

    Directory of Open Access Journals (Sweden)

    Daniel P Barry

    Full Text Available Once acquired, Helicobacter pylori infection is lifelong due to an inadequate innate and adaptive immune response. Our previous studies indicate that interactions among the various pathways of arginine metabolism in the host are critical determinants of outcomes following infection. Cationic amino acid transporter 2 (CAT2 is essential for transport of L-arginine (L-Arg into monocytic immune cells during H. pylori infection. Once within the cell, this amino acid is utilized by opposing pathways that lead to elaboration of either bactericidal nitric oxide (NO produced from inducible NO synthase (iNOS, or hydrogen peroxide, which causes macrophage apoptosis, via arginase and the polyamine pathway. Because of its central role in controlling L-Arg availability in macrophages, we investigated the importance of CAT2 in vivo during H. pylori infection. CAT2(-/- mice infected for 4 months exhibited decreased gastritis and increased levels of colonization compared to wild type mice. We observed suppression of gastric macrophage levels, macrophage expression of iNOS, dendritic cell activation, and expression of granulocyte-colony stimulating factor in CAT2(-/- mice suggesting that CAT2 is involved in enhancing the innate immune response. In addition, cytokine expression in CAT2(-/- mice was altered from an antimicrobial Th1 response to a Th2 response, indicating that the transporter has downstream effects on adaptive immunity as well. These findings demonstrate that CAT2 is an important regulator of the immune response during H. pylori infection.

  11. Transport mechanisms of trans-1-amino-3-fluoro[1-14C]cyclobutanecarboxylic acid in prostate cancer cells

    International Nuclear Information System (INIS)

    Introduction: We investigated the mechanisms of trans-1-amino-3-fluoro[1-14C]cyclobutanecarboxylic acid (anti-[14C]FACBC) transport by human-derived prostate cancer (PCa) cells and normal human prostatic epithelial cells (PrECs). Methods: Using PCa cells (DU145, PC-3, LNCaP) and PrECs, we performed the following in vitro experiments: time-course, kinetics, competitive inhibition by synthetic/naturally occurring amino acids (AAs), exchange transport with synthetic/naturally occurring AAs and pH-dependency of anti-[14C]FACBC uptake. We also examined the amino acid transporter (AAT) expression using flow cytometry. Results: The uptake of anti-[14C]FACBC by LNCaP and DU145 cells was higher than that by PC-3 and PrECs. The Km values for anti-[14C]FACBC were 64.4 and 191.7 μmol/L in the DU145 cells and PrECs, respectively. Total levels of anti-[14C]FACBC uptake were positively correlated with the expression level of system ASC in PCa cells. The contributions of Na+-dependent AATs to anti-[14C]FACBC uptake were greater than those of Na+-independent AATs, especially in PCa cells. In the presence of Na+, glutamine and serine showed the strongest inhibitory effect against anti-[14C]FACBC uptake, suggesting that system ASC, especially ASCT2, is an important AAT for anti-[14C]FACBC. In contrast, phenylalanine and 2-amino-bicyclo[2,2,1]heptane-2-carboxylic acid, but not N-ethylmaleimide, almost completely inhibited the anti-[14C]FACBC uptake in the absence of Na+, indicating the contribution of LAT1. In the exchange transport experiments, glutamine showed the strongest transstimulation of intracellular anti-[14C]FACBC efflux in DU145 cells. Furthermore, the contributions of Na+-independent AATs to the uptake of anti-[14C]FACBC in DU145 and PrECs were greater under acidic pH conditions than under neutral or alkaline pH conditions. Conclusions: Total uptake of anti-[14C]FACBC by PCa cells correlates with the expression level of system ASC in PCa cells. Furthermore, LAT1 is an

  12. Circumvention of defective neutral amino acid transport in Hartnup disease using tryptophan ethyl ester.

    Science.gov (United States)

    Jonas, A J; Butler, I J

    1989-07-01

    Tryptophan ethyl ester, a lipid-soluble tryptophan derivative, was used to bypass defective gastrointestinal neutral amino acid transport in a child with Hartnup disease. The child's baseline tryptophan concentrations in serum (20 +/- 6 microM) and cerebrospinal fluid (1.0 +/- 0.2 microM) were persistently less than 50% of normal values. Cerebrospinal fluid 5-hydroxyindoleacetic acid (5-HIAA), a serotonin metabolite, was also less than 50% of normal (21 +/- 2 ng/ml). Serum tryptophan concentrations increased only modestly and briefly after an oral challenge with 200 mg/kg of oral L-tryptophan, reflecting the absorptive defect. An oral challenge with 200 mg/kg of tryptophan ethyl ester resulted in a prompt increase in serum tryptophan to a peak of 555 microM. Sustained treatment with 20 mg/kg q6h resulted in normalization of serum (66 +/- 15 microM) and cerebrospinal fluid tryptophan concentrations (mean = 2.3 microM). Cerebrospinal fluid 5-HIAA increased to more normal concentrations (mean = 33 ng/ml). No toxicity was observed over an 8-mo period of treatment, chronic diarrhea resolved, and body weight, which had remained unchanged for 7 mo before ester therapy, increased by approximately 26%. We concluded that tryptophan ethyl ester is effective at circumventing defective gastrointestinal neutral amino acid transport and may be useful in the treatment of Hartnup disease. PMID:2472426

  13. Stable isotope tracer reveals that viviparous snakes transport amino acids to offspring during gestation.

    Science.gov (United States)

    Van Dyke, James U; Beaupre, Steven J

    2012-03-01

    Viviparity and placentation have evolved from oviparity over 100 times in squamate reptiles (lizards and snakes). The independent origins of placentation have resulted in a variety of placental morphologies in different taxa, ranging from simple apposition of fetal and maternal tissues to endotheliochorial implantation that is homoplasious with mammalian placentation. Because the eggs of oviparous squamates transport gases and water from the environment and calcium from the eggshell, the placentae of viviparous squamates are thought to have initially evolved to accomplish these functions from within the maternal oviduct. Species with complex placentae have also been shown to rely substantially, or even primarily, on placental transport of organic nutrients for embryonic nutrition. However, it is unclear whether species with only simple placentae are also capable of transporting organic nutrients to offspring. Among viviparous squamates, all of the snakes that have been studied thus far have been shown to have simple placentae. However, most studies of snake placentation are limited to a single lineage, the North American Natricinae. We tested the abilities of four species of viviparous snakes - Agkistrodon contortrix (Viperidae), Boa constrictor (Boidae), Nerodia sipedon (Colubridae: Natricinae) and Thamnophis sirtalis (Colubridae: Natricinae) - to transport diet-derived amino acids to offspring during gestation. We fed [(15)N]leucine to pregnant snakes, and compared offspring (15)N content with that of unlabeled controls. Labeled females allocated significantly more (15)N to offspring than did controls, but (15)N allocation did not differ among species. Our results indicate that viviparous snakes are capable of transporting diet-derived amino acids to their offspring during gestation, possibly via placentation.

  14. Assessment of Amino Acid/Drug Transporters for Renal Transport of [18F]Fluciclovine (anti-[18F]FACBC in Vitro

    Directory of Open Access Journals (Sweden)

    Masahiro Ono

    2016-10-01

    Full Text Available [18F]Fluciclovine (trans-1-amino-3-[18F]fluorocyclobutanecarboxylic acid; anti-[18F]FACBC, a positron emission tomography tracer used for the diagnosis of recurrent prostate cancer, is transported via amino acid transporters (AATs with high affinity (Km: 97–230 μM. However, the mechanism underlying urinary excretion is unknown. In this study, we investigated the involvement of AATs and drug transporters in renal [18F]fluciclovine reuptake. [14C]Fluciclovine (trans-1-amino-3-fluoro[1-14C]cyclobutanecarboxylic acid was used because of its long half-life. The involvement of AATs in [14C]fluciclovine transport was measured by apical-to-basal transport using an LLC-PK1 monolayer as model for renal proximal tubules. The contribution of drug transporters herein was assessed using vesicles/cells expressing the drug transporters P-glycoprotein (P-gp, breast cancer resistance protein (BCRP, multidrug resistance-associated protein 4 (MRP4, organic anion transporter 1 (OAT1, organic anion transporter 3 (OAT3 , organic cation transporter 2 (OCT2, organic anion transporting polypeptide 1B1 (OATP1B1, and organic anion transporting polypeptide 1B3 (OATP1B3. The apical-to-basal transport of [14C]fluciclovine was attenuated by l-threonine, the substrate for system alanine-serine-cysteine (ASC AATs. [14C]Fluciclovine uptake by drug transporter-expressing vesicles/cells was not significantly different from that of control vesicles/cells. Fluciclovine inhibited P-gp, MRP4, OAT1, OCT2, and OATP1B1 (IC50 > 2.95 mM. Therefore, system ASC AATs may be partly involved in the renal reuptake of [18F]fluciclovine. Further, given that [18F]fluciclovine is recognized as an inhibitor with millimolar affinity for the tested drug transporters, slow urinary excretion of [18F]fluciclovine may be mediated by system ASC AATs, but not by drug transporters.

  15. Inducible expression and pharmacology of the human excitatory amino acid transporter 2 subtype of L-glutamate transporter.

    Science.gov (United States)

    Dunlop, J; Lou, Z; Zhang, Y; McIlvain, H B

    1999-12-01

    1. In this study we have examined the use of the ecdysone-inducible mammalian expression system (Invitrogen) for the regulation of expression of the predominant L-glutamate transporter EAAT2 (Excitatory Amino Acid Transporter) in HEK 293 cells. 2. HEK 293 cells which were stably transformed with the regulatory vector pVgRXR (EcR 293 cells) were used for transfection of the human EAAT2 cDNA using the inducible vector pIND and a clone designated HEK/EAAT2 was selected for further characterization. 3. Na+-dependent L-glutamate uptake activity (3.2 pmol min-1 mg-1) was observed in EcR 293 cells and this was increased approximately 2 fold in the uninduced HEK/EAAT2 cells, indicating a low level of basal EAAT2 activity in the absence of exogenous inducing agent. Exposure of HEK/EAAT2 cells to the ecdysone analogue Ponasterone A (10 microM for 24 h) resulted in a > or = 10 fold increase in the Na+-dependent activity. 4. L-glutamate uptake into induced HEK/EAAT2 cells followed first-order Michaelis-Menten kinetics and Eadie-Hofstee transformation of the saturable uptake data produced estimates of kinetic parameters as follows; Km 52.7+/-7.5 microM, Vmax 3.8+/-0.9 nmol min-1 mg-1 protein. 5. The pharmacological profile of the EAAT2 subtype was characterized using a series of L-glutamate transport inhibitors and the rank order of inhibitory potency was similar to that described previously for the rat homologue GLT-1 and in synaptosomal preparations from rat cortex. 6. Addition of the EAAT2 modulator arachidonic acid resulted in an enhancement (155+/-5% control in the presence of 30 microM) of the L-glutamate transport capacity in the induced HEK/EAAT2 cells. 7. This study demonstrates that the expression of EAAT2 can be regulated in a mammalian cell line using the ecdysone-inducible mammalian expression system.

  16. Involvement of the Neutral Amino Acid Transporter SLC6A15 and Leucine in Obesity-Related Phenotypes

    OpenAIRE

    Jana Drgonova; Jacobsson, Josefin A.; Han, Joan C.; Yanovski, Jack A.; Robert Fredriksson; Claude Marcus; Schiöth, Helgi B; Uhl, George R.

    2013-01-01

    Brain pathways, including those in hypothalamus and nucleus of the solitary tract, influence food intake, nutrient preferences, metabolism and development of obesity in ways that often differ between males and females. Branched chain amino acids, including leucine, can suppress food intake, alter metabolism and change vulnerability to obesity. The SLC6A15 (v7-3) gene encodes a sodium-dependent transporter of leucine and other branched chain amino acids that is expressed by neurons in hypothal...

  17. The role of L-type amino acid transporters in the uptake of glyphosate across mammalian epithelial tissues.

    Science.gov (United States)

    Xu, Jiaqiang; Li, Gao; Wang, Zhuoyi; Si, Luqin; He, Sijie; Cai, Jialing; Huang, Jiangeng; Donovan, Maureen D

    2016-02-01

    Glyphosate is one of the most commonly used herbicides worldwide due to its broad spectrum of activity and reported low toxicity to humans. Glyphosate has an amino acid-like structure that is highly polar and shows low bioavailability following oral ingestion and low systemic toxicity following intravenous exposures. Spray applications of glyphosate in agricultural or residential settings can result in topical or inhalation exposures to the herbicide. Limited systemic exposure to glyphosate occurs following skin contact, and pulmonary exposure has also been reported to be low. The results of nasal inhalation exposures, however, have not been evaluated. To investigate the mechanisms of glyphosate absorption across epithelial tissues, the permeation of glyphosate across Caco-2 cells, a gastrointestinal epithelium model, was compared with permeation across nasal respiratory and olfactory tissues excised from cows. Saturable glyphosate uptake was seen in all three tissues, indicating the activity of epithelial transporters. The uptake was shown to be ATP and Na(+) independent, and glyphosate permeability could be significantly reduced by the inclusion of competitive amino acids or specific LAT1/LAT2 transporter inhibitors. The pattern of inhibition of glyphosate permeability across Caco-2 and nasal mucosal tissues suggests that LAT1/2 play major roles in the transport of this amino-acid-like herbicide. Enhanced uptake into the epithelial cells at barrier mucosae, including the respiratory and gastrointestinal tracts, may result in more significant local and systemic effects than predicted from glyphosate's passive permeability, and enhanced uptake by the olfactory mucosa may result in further CNS disposition, potentially increasing the risk for brain-related toxicities.

  18. Experimental lead poisoning and intestinal transport of glucose, amino acids, and sodium.

    Science.gov (United States)

    Wapnir, R A; Exeni, R A; McVicar, M; Lipshitz, F

    1977-03-01

    Juvenile rats fed a diet containing 1% lead acetate for 7 weeks, in addition to an impaired growth rate and renal function derangements, suffered malabsorption of glucose and certain amino acids, as assessed by an in vivo perfusion technique. The reduction in glucose absorption ranged between 10% and 31% when the carbohydrate was pumped in concentrations of 2-80 mM. This alteration was compatible with a noncompetitive type of transport inhibition. The intestinal absorption of glycine, lysine, and phenylalanine were, respectively, decreased 22, 18, and 15% when these amino acids were present at 1 mM levels. Sodium transport was severely reduced (57.6 +/- 17.9 (SEM) vs. 124.2 +/- 17.4 muEq/min-cm) and intestinal mucosa (Na+-K+)-ATPase was concomitantly lower in the lead-intoxicated rats (186.4 +/- 19.0 vs 268.4 +/- 29.8 nmol P/min-mg protein). However, this enzyme was not altered in liver and kidney. Furthermore, intestinal mucosa fructose-1,6-diphosphatase, succinic dehydrogenase, pyruvate kinase, and tryptophan hydroxylase were not different in experimental and control animals. These studies substantiate the presence of functional and biochemical abnormalities in the intestinal mucosa of young rats when fed substantial amounts of a soluble lead salt. It is, therefore, reasonable to accept the possibility that physiologic damage occurs in tissues directly subjected to high and persistent levels of a toxic agents, as it occurs in other organs, underscoring the parallelism between transport mechanisms at the renal and intestinal levels.

  19. 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.

  20. Age-related alterations in the diffusional transport of amino acids across the human Bruch's-choroid complex

    Science.gov (United States)

    Hussain, Ali A.; Rowe, Lisa; Marshall, John

    2002-01-01

    Photoreceptor maintenance is dependent on effective delivery of nutrients from the choroidal circulation by way of the acellular Bruch's membrane and the retinal pigment epithelium. Aging of Bruch's membrane is associated with thickening, increased cross linking of fibers, and deposition of debris culminating in reduced porosity. The present study has investigated the effects of aging on the diffusional transport of eight amino acids across Bruch's membrane in 19 human donors. Diffusion studies were carried out in Ussing chambers, and the amount of time-dependent transfer of amino acids across the preparation was quantified by reverse-phase high-performance liquid chromatography. Diffusion rates for all amino acids showed a significant linear decline with aging of donor. The importance of this reduction in delivery of amino acids is discussed with reference to both normal physiology and age-related macular degeneration.

  1. Amino Acid Transport Associated to Cluster of Differentiation 98 Heavy Chain (CD98hc) Is at the Cross-road of Oxidative Stress and Amino Acid Availability.

    Science.gov (United States)

    de la Ballina, Laura R; Cano-Crespo, Sara; González-Muñoz, Elena; Bial, Susanna; Estrach, Soline; Cailleteau, Laurence; Tissot, Floriane; Daniel, Hannelore; Zorzano, Antonio; Ginsberg, Mark H; Palacín, Manuel; Féral, Chloé C

    2016-04-29

    CD98hc functions as an amino acid (AA) transporter (together with another subunit) and integrin signaling enhancer. It is overexpressed in highly proliferative cells in both physiological and pathological conditions. CD98hc deletion induces strong impairment of cell proliferation in vivo and in vitro Here, we investigate CD98hc-associated AA transport in cell survival and proliferation. By using chimeric versions of CD98hc, the two functions of the protein can be uncoupled. Although recovering the CD98hc AA transport capacity restores the in vivo and in vitro proliferation of CD98hc-null cells, reconstitution of the integrin signaling function of CD98hc is unable to restore in vitro proliferation of those cells. CD98hc-associated transporters (i.e. xCT, LAT1, and y(+)LAT2 in wild-type cells) are crucial to control reactive oxygen species and intracellular AA levels, thus sustaining cell survival and proliferation. Moreover, in CD98hc-null cells the deficiency of CD98hc/xCT cannot be compensated, leading to cell death by ferroptosis. Supplementation of culture media with β-mercaptoethanol rescues CD98hc-deficient cell survival. Under such conditions null cells show oxidative stress and intracellular AA imbalance and, consequently, limited proliferation. CD98hc-null cells also present reduced intracellular levels of branched-chain and aromatic amino acids (BCAAs and ARO AAs, respectively) and induced expression of peptide transporter 1 (PEPT1). Interestingly, external supply of dipeptides containing BCAAs and ARO AAs rescues cell proliferation and compensates for impaired uptake of CD98hc/LAT1 and CD98hc/y(+)LAT2. Our data establish CD98hc as a master protective gene at the cross-road of redox control and AA availability, making it a relevant therapeutic target in cancer. PMID:26945935

  2. Highly conserved asparagine 82 controls the interaction of Na+ with the sodium-coupled neutral amino acid transporter SNAT2.

    Science.gov (United States)

    Zhang, Zhou; Gameiro, Armanda; Grewer, Christof

    2008-05-01

    The neutral amino acid transporter 2 (SNAT2), which belongs to the SLC38 family of solute transporters, couples the transport of amino acid to the cotransport of one Na(+) ion into the cell. Several polar amino acids are highly conserved within the SLC38 family. Here, we mutated three of these conserved amino acids, Asn(82) in the predicted transmembrane domain 1 (TMD1), Tyr(337) in TMD7, and Arg(374) in TMD8; and we studied the functional consequences of these modifications. The mutation of N82A virtually eliminated the alanine-induced transport current, as well as amino acid uptake by SNAT2. In contrast, the mutations Y337A and R374Q did not abolish amino acid transport. The K(m) of SNAT2 for its interaction with Na(+), K(Na(+)), was dramatically reduced by the N82A mutation, whereas the more conservative mutation N82S resulted in a K(Na(+)) that was in between SNAT2(N82A) and SNAT2(WT). These results were interpreted as a reduction of Na(+) affinity caused by the Asn(82) mutations, suggesting that these mutations interfere with the interaction of SNAT2 with the sodium ion. As a consequence of this dramatic reduction in Na(+) affinity, the apparent K(m) of SNAT2(N82A) for alanine was increased 27-fold compared with that of SNAT2(WT). Our results demonstrate a direct or indirect involvement of Asn(82) in Na(+) coordination by SNAT2. Therefore, we predict that TMD1 is crucial for the function of SLC38 transporters and that of related families.

  3. The orphan transporter v7-3 (slc6a15) is a Na+-dependent neutral amino acid transporter (B0AT2)

    DEFF Research Database (Denmark)

    Bröer, Angelika; Tietze, Nadine; Kowalczuk, Sonja;

    2006-01-01

    Transporters of the SLC6 (solute carrier 6) family play an important role in the removal of neurotransmitters in brain tissue and in amino acid transport in epithelial cells. In the present study, we demonstrate that mouse v7-3 (slc6a15) encodes a transporter for neutral amino acids...... low-affinity substrates of the transporter, with K(0.5) values in the millimolar range. Transport of neutral amino acids via B(0)AT2 was Na+-dependent, Cl--independent and electrogenic. Superfusion of mouse B(0)AT2-expressing oocytes with amino acid substrates generated robust inward currents. Na......+-activation kinetics of proline transport and uptake under voltage clamp suggested a 1:1 Na+/amino acid co-transport stoichiometry. Susbtrate and co-substrate influenced each other's K(0.5) values, suggesting that they share the same binding site. A mouse B(0)AT2-like transport activity was detected in synaptosomes...

  4. Isolation of a spontaneous CHO amino acid transport mutant by a combination of tritium suicide and replica plating

    International Nuclear Information System (INIS)

    A spontaneous transport mutant of Chinese hamster ovary cells, CHY-1, was isolated by a combination of [3H]proline suicide and replica plating. The mutant took up less tritium than the parent, resulting in a lower killing rate during storage. Transport by four separate amino acid transport systems (A, ASC, L, Ly+) was examined. The CHY-1 mutant exhibited normal uptake via the ASC, L, and Ly+ systems. By contrast, uptake of the most specific substrate of the A system, 2-(methylamino)-isobutyric acid, was significantly reduced at low, but not high, concentrations, due to a 3.5-fold increase in Km and a 1.5-fold increase in Vmax. Taken together, these data suggest that the CHY-1 mutation may be in the structural gene coding for the A transport protein. The tritium suicide procedure is discussed, and general equations are derived to predict the maximum storage time for the survival of one mutant cell and the optimum size of the cell population for maximum mutant enrichment

  5. Insulin binding and stimulation of hexose and amino acid transport by normal and receptor-defective human fibroblasts

    International Nuclear Information System (INIS)

    The authors analyzed insulin receptors in cells cultured from a sibship of related parents who had two offspring with severe insulin resistance (Leprechaunism). 124I-Insulin (1 ng/ml) binding to skin fibroblasts from the proband, mother, and father was 9, 60 and 62% of control cells, respectively, at equilibrium, Non-linear regression analysis, utilizing a two receptors model, of curvilinear Scatchard plots indicated a reduced number of high-affinity binding sites in both parents. Influx of L-Proline (System A), L-Serine (ASC) and L-Leucine (L) was similar in control and mutant cells. Similarly, during the depletion of intracellular amino acid pools, there was a release from transinhibition for System A and a decrease of transstimulation of Systems ASC and L in both cell lines. Surprisingly, insulin augmented, normally, A system influx with an ED50 = 70 ng/ml at 240C and 7 ng/ml at 370C. By contrast insulin failed to simulated 3-0-methyl-D-glucose influx into the proband's cells, while normal cells were stimulated 30% with an ED50 of 6 ng/ml. These results indicate that defective high-affinity insulin binding is inherited as an autosomal recessive trait; that general membrane functions are intact; that insulin regulates A system amino acid and hexose transport by two different mechanisms; and, that the latter mechanism is impaired by this family's receptor mutation

  6. Overexpression of L-Type Amino Acid Transporter 1 (LAT1) and 2 (LAT2): Novel Markers of Neuroendocrine Tumors

    Science.gov (United States)

    Barollo, Susi; Bertazza, Loris; Watutantrige-Fernando, Sara; Censi, Simona; Cavedon, Elisabetta; Galuppini, Francesca; Pennelli, Gianmaria; Fassina, Ambrogio; Citton, Marilisa; Rubin, Beatrice; Pezzani, Raffaele; Benna, Clara; Opocher, Giuseppe; Iacobone, Maurizio; Mian, Caterina

    2016-01-01

    Background 6-18F-fluoro-L-3,4-dihydroxyphenylalanine (18F-FDOPA) PET is a useful tool in the clinical management of pheochromocytoma (PHEO) and medullary thyroid carcinoma (MTC). 18F-FDOPA is a large neutral amino acid biochemically resembling endogenous L-DOPA and taken up by the L-type amino acid transporters (LAT1 and LAT2). This study was conducted to examine the expression of the LAT system in PHEO and MTC. Methods Real-time PCR and Western blot analyses were used to assess LAT1 and LAT2 gene and protein expression in 32 PHEO, 38 MTC, 16 normal adrenal medulla and 15 normal thyroid tissue samples. Immunohistochemistry method was applied to identify the proteins’ subcellular localization. Results LAT1 and LAT2 were overexpressed in both PHEO and MTC by comparison with normal tissues. LAT1 presented a stronger induction than LAT2, and their greater expression was more evident in PHEO (15.1- and 4.1-fold increases, respectively) than in MTC (9.9- and 4.1-fold increases, respectively). Furthermore we found a good correlation between LAT1/2 and GLUT1 expression levels. A positive correlation was also found between urinary noradrenaline and adrenaline levels and LAT1 gene expression in PHEO. The increased expression of LAT1 is also confirmed at the protein level, in both PHEO and MTC, with a strong cytoplasmic localization. Conclusions The present study is the first to provide experimental evidence of the overexpression in some NET cancers (such as PHEO or MTC) of L-type amino acid transporters, and the LAT1 isoform in particular, giving the molecular basis to explain the increase of the DOPA uptake seen in such tumor cells. PMID:27224648

  7. Overexpression of L-Type Amino Acid Transporter 1 (LAT1 and 2 (LAT2: Novel Markers of Neuroendocrine Tumors.

    Directory of Open Access Journals (Sweden)

    Susi Barollo

    Full Text Available 6-18F-fluoro-L-3,4-dihydroxyphenylalanine (18F-FDOPA PET is a useful tool in the clinical management of pheochromocytoma (PHEO and medullary thyroid carcinoma (MTC. 18F-FDOPA is a large neutral amino acid biochemically resembling endogenous L-DOPA and taken up by the L-type amino acid transporters (LAT1 and LAT2. This study was conducted to examine the expression of the LAT system in PHEO and MTC.Real-time PCR and Western blot analyses were used to assess LAT1 and LAT2 gene and protein expression in 32 PHEO, 38 MTC, 16 normal adrenal medulla and 15 normal thyroid tissue samples. Immunohistochemistry method was applied to identify the proteins' subcellular localization.LAT1 and LAT2 were overexpressed in both PHEO and MTC by comparison with normal tissues. LAT1 presented a stronger induction than LAT2, and their greater expression was more evident in PHEO (15.1- and 4.1-fold increases, respectively than in MTC (9.9- and 4.1-fold increases, respectively. Furthermore we found a good correlation between LAT1/2 and GLUT1 expression levels. A positive correlation was also found between urinary noradrenaline and adrenaline levels and LAT1 gene expression in PHEO. The increased expression of LAT1 is also confirmed at the protein level, in both PHEO and MTC, with a strong cytoplasmic localization.The present study is the first to provide experimental evidence of the overexpression in some NET cancers (such as PHEO or MTC of L-type amino acid transporters, and the LAT1 isoform in particular, giving the molecular basis to explain the increase of the DOPA uptake seen in such tumor cells.

  8. Amino acids in Arctic aerosols

    Directory of Open Access Journals (Sweden)

    E. Scalabrin

    2012-07-01

    Full Text Available Amino acids are significant components of atmospheric aerosols, affecting organic nitrogen input to marine ecosystems, atmospheric radiation balance, and the global water cycle. The wide range of amino acid reactivities suggest that amino acids may serve as markers of atmospheric transport and deposition of particles. Despite this potential, few measurements have been conducted in remote areas to assess amino acid concentrations and potential sources. Polar regions offer a unique opportunity to investigate atmospheric processes and to conduct source apportionment studies of such compounds. In order to better understand the importance of amino acid compounds in the global atmosphere, we determined free amino acids (FAAs in seventeen size-segregated aerosol samples collected in a polar station in the Svalbard Islands from 19 April until 14 September 2010. We used an HPLC coupled with a tandem mass spectrometer (ESI-MS/MS to analyze 20 amino acids to quantify compounds at fmol m−3 levels. Mean total FAA concentration was 1070 fmol m−3 where serine and glycine were the most abundant compounds in almost all samples and accounted for 45–60% of the total amino acid relative abundance. The other eighteen compounds had average concentrations between 0.3 and 98 fmol m−3. The higher amino acid concentrations were present in the ultrafine aerosol fraction (<0.49 μm and accounted for the majority of the total amino acid content. Local marine sources dominate the boreal summer amino acid concentrations, with the exception of the regional input from Icelandic volcanics.

  9. Quantitative amino acid profiling and stable isotopically labeled amino acid tracer enrichment used for in vivo human systemic and tissue kinetics measurements.

    Science.gov (United States)

    Bornø, Andreas; van Hall, Gerrit

    2014-03-01

    An important area within clinical functional metabolomics is in vivo amino acid metabolism and protein turnover measurements for which accurate amino acid concentrations and stable isotopically labeled amino acid enrichments are mandatory not the least when tissue metabolomics is determined. The present study describes a new sensitive liquid chromatography tandem mass-spectrometry method quantifying 20 amino acids and their tracer(s) ([ring-(13)C6]/D5Phenylalanine) in human plasma and skeletal muscle specimens. Before analysis amino acids were extracted and purified via deprotonization/ion exchange, derivatized using a phenylisothiocyanate reagent and each amino acid was quantitated with its own stable isotopically labeled internal standard (uniformly labeled-(13)C/(15)N). The method was validated according to general recommendations for chromatographic analytical methods. The calibration curve correlations for amino acids were on average; r(2)=0.998. Interday accuracy for amino acids determined in spiked plasma was on average 97.3% and the coefficient of variation (CV) was 2.6%. The ([ring-(13)C6]/D5Phenylalanine) enrichment CV's for machine reproducibility in muscle tissue fluid and plasma were 4.4 and 0.8%, and the interday variability was 3.4% and the recovery was 90.5%, respectively. In conclusion, we have developed and validated a method for quantitative amino acid profiling that meets the requirements for systemic and tissue human in vivo amino acid and protein turnover kinetics measurements. Moreover, citrulline, ornithine, π-methyl-histidine, τ-methyl-l-histidine, hydroxy-proline and carnitine were analysed but when similar precision and accuray are required an additional stable istopically labeled internal standard for these meatablites should be be added.

  10. Amino acids and carbohydrates absorption by Na+-dependent transporters in the pyloric ceca of Hoplias malabaricus (Erythrinidae

    Directory of Open Access Journals (Sweden)

    Vieira Vania Lucia Pimentel

    2001-01-01

    Full Text Available Information about amino acids and carbohydrate absorption in fish is important to formulate an adequate diet to obtain optimal growth. Therefore, the objective of this study was to investigate if Na+-dependent transporters are involved on the absorption of glycine, L-glutamine, L-leucine, L-lysine, L-proline, L-alanine, and the carbohydrates fructose and glucose in the pyloric ceca of Hoplias malabaricus. The pyloric ceca were mounted in a system of continuous perfusion "in vitro". Amino acids and carbohydrates were placed on the mucosal side at concentrations of 10, 20, and 40mM. The serosal side of the pyloric ceca was positive in relation to the mucosal side. The addition of glycine, L-glutamine, L-leucine, L-lysine, L-proline (all tested concentrations, and glucose (at concentrations of 20 and 40mM increased the positivity of the serosal side, indicating the presence of Na+-dependent transporters in the absorption of these substances. L-alanine and fructose did not change the positivity of the serosal side. The pyloric ceca seem to be the main site of nutrient absorption in the digestive tract of H. malabaricus.

  11. Expression Profile of Cationic Amino Acid Transporters in Rats with Endotoxin-Induced Uveitis

    Directory of Open Access Journals (Sweden)

    Yung-Ray Hsu

    2016-01-01

    Full Text Available Purpose. The transcellular arginine transportation via cationic amino acid transporter (CAT is the rate-limiting step in nitric oxide (NO synthesis, which is crucial in intraocular inflammation. In this study, CAT isoforms and inducible nitric oxide synthase (iNOS expression was investigated in endotoxin-induced uveitis (EIU. Methods. EIU was induced in Lewis rats by lipopolysaccharide (LPS injection. In the treatment group, the rats were injected intraperitoneally with the proteasome inhibitor bortezomib before EIU induction. After 24 hours, leukocyte quantification, NO measurement of the aqueous humor, and histopathological examination were evaluated. The expression of CAT isoforms and iNOS was determined by reverse transcription-polymerase chain reaction, western blotting, and immunofluorescence staining. Nuclear factor-kappa B (NF-κB binding activity was evaluated by electrophoretic mobility shift assay. The mouse macrophage cell line RAW 264.7 was used to validate the in vivo findings. Results. LPS significantly stimulated iNOS, CAT-2A, and CAT-2B mRNA and protein expression but did not affect CAT-1 in EIU rats and RAW 264.7 cells. Bortezomib attenuated inflammation and inhibited iNOS, CAT-2A, and CAT-2B expression through NF-κB inhibition. Conclusions. CAT-2 and iNOS, but not CAT-1, are specifically involved in EIU. NF-κB is essential in the induction of CAT-2 and iNOS in EIU.

  12. Membrane transporters for the special amino acid glutamine: Structure/function relationships and relevance to human health.

    Science.gov (United States)

    Pochini, Lorena; Scalise, Mariafrancesca; Galluccio, Michele; Indiveri, Cesare

    2014-08-01

    Glutamine together with glucose is essential for body’s homeostasis. It is the most abundant amino acid and is involved in many biosynthetic, regulatory and energy production processes. Several membrane transporters which differ in transport modes, ensure glutamine homeostasis by coordinating its absorption, reabsorption and delivery to tissues. These transporters belong to different protein families, are redundant and ubiquitous. Their classification, originally based on functional properties, has recently been associated with the SLC nomenclature. Function of glutamine transporters is studied in cells over-expressing the transporters or, more recently in proteoliposomes harboring the proteins extracted from animal tissues or over-expressed in microorganisms. The role of the glutamine transporters is linked to their transport modes and coupling with Na+ and H+. Most transporters share specificity for other neutral or cationic amino acids. Na+-dependent co-transporters efficiently accumulate glutamine while antiporters regulate the pools of glutamine and other amino acids. The most acknowledged glutamine transporters belong to the SLC1, 6, 7 and 38 families. The members involved in the homeostasis are the co-transporters B0AT1 and the SNAT members 1, 2, 3, 5 and 7; the antiporters ASCT2, LAT1 and 2. The last two are associated to the ancillary CD98 protein. Some information on regulation of the glutamine transporters exist, which, however, need to be deepened. No information at all is available on structures, besides some homology models obtained using similar bacterial transporters as templates. Some models of rat and human glutamine transporters highlight very similar structures between the orthologues. Moreover the presence of glycosylation and/or phosphorylation sites located at the extracellular or intracellular faces has been predicted. ASCT2 and LAT1 are over-expressed in several cancers, thus representing potential targets for pharmacological intervention.

  13. Excitatory amino acid transporters EAAT-1 and EAAT-2 in temporal lobe and hippocampus in intractable temporal lobe epilepsy

    DEFF Research Database (Denmark)

    Sarac, Sinan; Afzal, Shoaib; Broholm, Helle;

    2009-01-01

    extra-cellular clearance of glutamate by excitatory amino acid transporters (EAAT-1 to EAAT-5). EAAT-1 and EAAT-2 are mainly expressed on astroglial cells for the reuptake of glutamate from the extra-cellular space. We have studied the expression of EAAT-1 and EAAT-2 in the hippocampus and temporal lobe...

  14. 21 CFR 862.1055 - Newborn screening test system for amino acids, free carnitine, and acylcarnitines using tandem...

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Newborn screening test system for amino acids... screening test system for amino acids, free carnitine, and acylcarnitines using tandem mass spectrometry. (a) Identification. A newborn screening test system for amino acids, free carnitine, and acylcarnitines using...

  15. Cloning and chromosomal localization of a human kidney cDNA involved in cystine, dibasic, and neutral amino acid transport.

    OpenAIRE

    Lee, W S; Wells, R G; Sabbag, R V; Mohandas, T K; Hediger, M A

    1993-01-01

    We have recently cloned, sequenced, and characterized a rat kidney cDNA (D2) that stimulates cystine as well as dibasic and neutral amino acid transport. In order to evaluate the role of this protein in human inherited diseases such as cystinuria, we have isolated a human D2 clone (D2H) by low stringency screening of a human kidney cDNA library using the radiolabeled D2 insert as a probe. The D2H cDNA is 2284 nucleotides long and encodes a 663 amino acid protein that is 80% identical to the r...

  16. Amino Acid Crossword Puzzle

    Science.gov (United States)

    Sims, Paul A.

    2011-01-01

    Learning the 20 standard amino acids is an essential component of an introductory course in biochemistry. Later in the course, the students study metabolism and learn about various catabolic and anabolic pathways involving amino acids. Learning new material or concepts often is easier if one can connect the new material to what one already knows;…

  17. Cationic amino acid transporter-2 regulates immunity by modulating arginase activity.

    Directory of Open Access Journals (Sweden)

    Robert W Thompson

    2008-03-01

    Full Text Available Cationic amino acid transporters (CAT are important regulators of NOS2 and ARG1 activity because they regulate L-arginine availability. However, their role in the development of Th1/Th2 effector functions following infection has not been investigated. Here we dissect the function of CAT2 by studying two infectious disease models characterized by the development of polarized Th1 or Th2-type responses. We show that CAT2(-/- mice are significantly more susceptible to the Th1-inducing pathogen Toxoplasma gondii. Although T. gondii infected CAT2(-/- mice developed stronger IFN-gamma responses, nitric oxide (NO production was significantly impaired, which contributed to their enhanced susceptibility. In contrast, CAT2(-/- mice infected with the Th2-inducing pathogen Schistosoma mansoni displayed no change in susceptibility to infection, although they succumbed to schistosomiasis at an accelerated rate. Granuloma formation and fibrosis, pathological features regulated by Th2 cytokines, were also exacerbated even though their Th2 response was reduced. Finally, while IL-13 blockade was highly efficacious in wild-type mice, the development of fibrosis in CAT2(-/- mice was largely IL-13-independent. Instead, the exacerbated pathology was associated with increased arginase activity in fibroblasts and alternatively activated macrophages, both in vitro and in vivo. Thus, by controlling NOS2 and arginase activity, CAT2 functions as a potent regulator of immunity.

  18. Free amino acids in the nervous system of the amphioxus Branchiostoma lanceolatum. A comparative study

    Directory of Open Access Journals (Sweden)

    2006-04-01

    Full Text Available The cephalochordate amphioxus is the closest invertebrate relative to vertebrates. In this study, using HPLC technique, free L-amino acids (L-AAs and D-aspartic acid (D-Asp have been detected in the nervous system of the amphioxus Branchiostoma lanceolatum. Among other amino acids glutamate, aspartate, glycine, alanine and serine are the amino acids found at the greatest concentrations. As it occurs in the nervous system of other animal phyla, glutamate (L-Glu and aspartate (L-Asp are present at very high concentrations in the amphioxus nervous system compared to other amino acids, whereas the concentration of taurine and γ-aminobutyric acid (GABA is very low. Interestingly, as it is the case in vertebrates, D-aspartic acid is present as an endogenous compound in amphioxus nervous tissues. The physiological function of excitatory amino acids, and D-aspartate in particular, are discussed in terms of evolution of the nervous system under an Evo-fun (Evolution of function perspective.

  19. 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.

  20. Inhibition of Large Neutral Amino Acid Transporters Suppresses Kynurenic Acid Production Via Inhibition of Kynurenine Uptake in Rodent Brain.

    Science.gov (United States)

    Sekine, Airi; Kuroki, Yusuke; Urata, Tomomi; Mori, Noriyuki; Fukuwatari, Tsutomu

    2016-09-01

    The tryptophan metabolite, kynurenic acid (KYNA), is a preferential antagonist of the α7 nicotinic acetylcholine receptor and N-methyl-D-aspartic acid receptor at endogenous brain concentrations. Recent studies have suggested that increases of brain KYNA levels are involved in psychiatric disorders such as schizophrenia and depression, and regulation of KYNA production has become a new target for treatment of these diseases. Kynurenine (KYN), the immediate precursor of KYNA, is transported into astrocytes via large neutral amino acid transporters (LATs). In the present study, the effect of LATs regulation on KYN uptake and KYNA production was investigated in vitro and in vivo using an LATs inhibitor, 2-aminobicyclo-(2,2,1)-heptane-2-carboxylic acid (BCH). In the in vitro study, cortical slices of rat brain were incubated with a physiological concentration of KYN and 3 µmol/L-3 mmol/L BCH. BCH inhibited KYNA production and KYN uptake in a dose-dependent manner, and their IC50 values were 90.7 and 97.4 µmol/L, respectively. In the in vivo study, mice were administered KYN (50 mg/kg BW) orally and BCH (200 mg/kg BW) intravenously. Administration of KYN increased brain KYN and KYNA levels compared with the mice treated with vehicle, whereas additional administration of BCH suppressed KYN-induced elevations in KYN and KYNA levels to 50 and 70 % in the brain. These results suggest that inhibition of LATs prevented the increase of KYNA production via blockade of KYN uptake in the brain in vitro and in vivo. LATs can be a target to modulate brain function by regulation of KYNA production in the brain. PMID:27161376

  1. Azetidinic amino acids

    DEFF Research Database (Denmark)

    Bräuner-Osborne, Hans; Bunch, Lennart; Chopin, Nathalie;

    2005-01-01

    A set of ten azetidinic amino acids, that can be envisioned as C-4 alkyl substituted analogues of trans-2-carboxyazetidine-3-acetic acid (t-CAA) and/or conformationally constrained analogues of (R)- or (S)-glutamic acid (Glu) have been synthesized in a diastereo- and enantiomerically pure form fr...

  2. Amino acid racemisation dating

    Energy Technology Data Exchange (ETDEWEB)

    Murray-Wallace, C.V. [University of Wollongong, Wollongong, NSW (Australia). School of Geosciences

    1999-11-01

    The potential of the time-dependent amino acid racemisation reaction as a method of age assessment was first reported by Hare and Abelson (1968). They noted that in specimens of the bivalve mollusc Mercenaria sp., greater concentrations of amino acids in the D-configuration with increasing fossil age. Hare and Abelson (1968) also reported negligible racemisation in a modern specimen of Mecanaria sp. On this basis they suggested that the extent of amino acid racemisation (epimerisation in the case of isoleucine) may be used to assess the age of materials within and beyond the range of radiocarbon dating. For the past thirty years amino acid racemisation has been extensively applied in Quaternary research as a method of relative and numeric dating, and a particularly large literature has emerged on the subject 12 refs.

  3. Amino Acid Metabolism Disorders

    Science.gov (United States)

    Metabolism is the process your body uses to make energy from the food you eat. Food is ... One group of these disorders is amino acid metabolism disorders. They include phenylketonuria (PKU) and maple syrup ...

  4. Pulmonary alveolar epithelial uptake of S-nitrosothiols is regulated by L-type amino acid transporter.

    Science.gov (United States)

    Granillo, Olivia M; Brahmajothi, Mulugu V; Li, Sheng; Whorton, A Richard; Mason, S Nicholas; McMahon, Timothy J; Auten, Richard L

    2008-07-01

    Nitric oxide (NO) effects are often mediated via S-nitrosothiol (SNO) formation; SNO uptake has recently been shown to be mediated in some cell types via system L-type amino acid transporters (LAT-1, 2). Inhaled NO therapy may exert some biological effects via SNO formation. We therefore sought to determine if pulmonary epithelial SNO uptake depended on LAT or peptide transporter 2 (PEPT2). Both LAT-1 and PEPT2 proteins were detected by immunoblot and immunocytochemistry in L2 cells and rat lung. We tested SNO uptake through the transporters by exposing rat alveolar epithelial cells (L2 and type II) to RSNOs: S-nitrosoglutathione, S-nitrosocysteinylglycine (SNO-Cys-Gly), S-nitrosocysteine (CSNO), and to NO donor diethylamine NONOate (DEA-NONOate). SNO was detected in cell lysates by ozone chemiluminescence. NO uptake was detected by fluorescence in alveolar epithelial cells loaded with 4-amino-5-methylamino-2',7'-difluorofluorescein (DAF-FM) diacetate cultured in submersion and exposed to RSNOs and DEA NONOate. Addition of L-Cys but not D-Cys to RSNOs or DEA NONOate increased SNO and DAF-FM signal that was inhibited by coincubation with LAT competitors. Incubation of cells with PEPT2 substrate SNO-Cys-Gly showed no increase in SNO or DAF-FM signal unless incubated with L-Cys. This was unaffected by PEPT2 inhibition. We conclude that RSNOs (thionitrites, S-nitrosothiols) and NO enter alveolar epithelial cells predominantly by S-nitrosation of L-Cys, which is then imported through LAT.

  5. IGF-I regulates redox status in breast cancer cells by activating the amino acid transport molecule xC-.

    Science.gov (United States)

    Yang, Yuzhe; Yee, Douglas

    2014-04-15

    Insulin-like growth factors (IGF) stimulate cell growth in part by increasing amino acid uptake. xCT (SLC7A11) encodes the functional subunit of the cell surface transport system xC(-), which mediates cystine uptake, a pivotal step in glutathione synthesis and cellular redox control. In this study, we show that IGF-I regulates cystine uptake and cellular redox status by activating the expression and function of xCT in estrogen receptor-positive (ER(+)) breast cancer cells by a mechanism that relies on the IGF receptor substrate-1 (IRS-1). Breast cancer cell proliferation mediated by IGF-I was suppressed by attenuating xCT expression or blocking xCT activity with the pharmacologic inhibitor sulfasalazine (SASP). Notably, SASP sensitized breast cancer cells to inhibitors of the type I IGF receptor (IGF-IR) in a manner reversed by the reactive oxygen species (ROS) scavenger N-acetyl-L-cysteine. Thus, IGF-I promoted the proliferation of ER(+) breast cancer cells by regulating xC(-) transporter function to protect cancer cells from ROS in an IRS-1-dependent manner. Our findings suggest that inhibiting xC(-) transporter function may synergize with modalities that target the IGF-IR to heighten their therapeutic effects.

  6. Excitatory amino acid transporter 2 downregulation correlates with thalamic neuronal death following kainic acid-induced status epilepticus in rat.

    Science.gov (United States)

    Sakurai, Masashi; Kurokawa, Haruna; Shimada, Akinori; Nakamura, Kazuhiro; Miyata, Hajime; Morita, Takehito

    2015-02-01

    Recurrent seizures without interictal resumption (status epilepticus) have been reported to induce neuronal death in the midline thalamic region that has functional roles in memory and decision-making; however, the pathogenesis underlying status epilepticus-induced thalamic neuronal death is yet to be determined. We performed histological and immunohistochemical studies as well as cerebral blood flow measurement using 4.7 tesla magnetic resonance imaging spectrometer on midline thalamic region in Sprague-Dawley rats (n = 75, male, 7 weeks after birth, body weight 250-300 g) treated with intraperitoneal injection of kainic acid (10 mg/kg) to induce status epilepticus (n = 55) or normal saline solution (n = 20). Histological study using paraffin-embedded specimens revealed neuronal death showing ischemic-like changes and Fluoro-Jade C positivity with calcium deposition in the midline thalamic region of epileptic rats. The distribution of neuronal death was associated with focal loss of immunoreactivity for excitatory amino acid transporter 2 (EAAT2), stronger immunoreaction for glutamate and increase in number of Iba-1-positive microglial cells showing swollen cytoplasm and long processes. Double immunofluorescence study demonstrated co-expression of interleukin-1 beta (IL-1β) and inducible nitric oxide synthase (iNOS) within microglial cells, and loss of EAAT2 immunoreactivity in reactive astrocytes. These microglial alterations and astrocytic EAAT2 downregulation were also observed in tissue without obvious neuronal death in kainic acid-treated rats. These results suggest the possible role of glutamate excitotoxicity in neuronal death in the midline thalamic region following kainic acid-induced status epilepticus due to astrocytic EAAT2 downregulation following microglial activation showing upregulation of IL-1β and iNOS.

  7. Amino Acids from a Comet

    Science.gov (United States)

    Cook, Jamie Elisla

    2009-01-01

    NASA's Stardust spacecraft returned samples from comet 81P/Wild 2 to Earth in January 2006. Examinations of the organic compounds in cometary samples can reveal information about the prebiotic organic inventory present on the early Earth and within the early Solar System, which may have contributed to the origin of life. Preliminary studies of Stardust material revealed the presence of a suite of organic compounds including several amines and amino acids, but the origin of these compounds (cometary- vs. terrestrial contamination) could not be identified. We have recently measured the carbon isotopic ratios of these amino acids to determine their origin, leading to the first detection of a coetary amino acid.

  8. L-leucine, L-methionine, and L-phenylalanine share a Na(+)/K (+)-dependent amino acid transporter in shrimp hepatopancreas.

    Science.gov (United States)

    Duka, Ada; Ahearn, Gregory A

    2013-08-01

    Hepatopancreatic brush border membrane vesicles (BBMV), made from Atlantic White shrimp (Litopenaeus setiferus), were used to characterize the transport properties of (3)H-L-leucine influx by these membrane systems and how other essential amino acids and the cations, sodium and potassium, interact with this transport system. (3)H-L-leucine uptake by BBMV was pH-sensitive and occurred against transient transmembrane concentration gradients in both Na(+)- and K(+)-containing incubation media, suggesting that either cation was capable of providing a driving force for amino acid accumulation. (3)H-L-leucine uptake in NaCl or KCl media were each three times greater in acidic pH (pH 5.5) than in alkaline pH (pH 8.5). The essential amino acid, L-methionine, at 20 mM significantly (p  0.05) and may represent an L-methionine- and cation-independent transport system. (3)H-L-leucine influxes in both NaCl and KCl incubation media were hyperbolic functions of [L-leucine], following the carrier-mediated Michaelis-Menten equation. In NaCl, (3)H-L-leucine influx displayed a low apparent K M (high affinity) and low apparent J max, while in KCl the transport exhibited a high apparent K M (low affinity) and high apparent J max. L-methionine or L-phenylalanine (7 and 20 mM) were competitive inhibitors of (3)H-L-leucine influxes in both NaCl and KCl media, producing a significant (p phenylalanine-shared carrier system that is enhanced by acidic pH and can be stimulated by either Na(+) or K(+) acting as co-transport drivers binding to shared activator sites.

  9. Development of new chiral ligand exchange capillary electrophoresis system with amino acid ionic liquids ligands and its application in studying the kinetics of L-amino acid oxidase

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Bingbing [Beijing National Laboratory for Molecular Sciences, Key Lab of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); College of Food Sciences and Engineering, Shandong Agricultural University, Tai’an, Shandong 271018 (China); Mu, Xiaoyu [Beijing National Laboratory for Molecular Sciences, Key Lab of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Qi, Li, E-mail: qili@iccas.ac.cn [Beijing National Laboratory for Molecular Sciences, Key Lab of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

    2014-04-01

    Highlights: • Novel amino acid ionic liquids with pyridinium as cations and L-lysine as anion were synthesized. • These synthesized AAILs have been explored as the ligands coordinated with Zn(II) in CLE-CE system. • The developed CLE-CE method could be used for the enantioseparation of Dns-D, L-amino acids. • The kinetic contents of L-amino acid oxidase were investigated with the proposed CLE-CE system. - Abstract: New kinds of amino acid ionic liquids (AAILs) with pyridinium as cations and L-lysine (L-Lys) as anion have been developed as the available chiral ligands coordinated with Zn(II) in chiral ligand-exchange capillary electrophoresis (CLE-CE). Four kinds of AAILs, including [1-ethylpyridinium][L-lysine], 1-butylpyridinium][L-lysine], [1-hexylpyridinium][L-lysine] and 1-[octylpyridinium][L-lysine], were successfully synthesized and characterized by nuclear magnetic resonance and mass spectrometry. Compared with other AAILs, the best chiral separation of Dns-D, L-amino acids could be achieved when [1-ethylpyridinium][L-lysine] was chosen as the chiral ligand. It has been found that after investigating the influence of key factors on the separation efficiency, such as pH of buffer solution, the ratio of Zn(II) to ligand and complex concentration, eight pairs of Dns-D, L-AAs enantiomers could be baseline separated and three pairs were partly separated under the optimum conditions. The proposed CLE-CE method also exhibited favorable quantitative analysis property of Dns-D, L-Met with good linearity (r{sup 2} = 0.998) and favorable repeatability (RSD ≤ 1.5%). Furthermore, the CLE-CE system was applied in investigating the kinetic contents of L-amino acid oxidase, which implied that the proposed system has the potential in studying the enzymatic reaction mechanism.

  10. Impacts of birth weight on plasma, liver and skeletal muscle neutral amino acid profiles and intestinal amino acid transporters in suckling Huanjiang mini-piglets.

    Directory of Open Access Journals (Sweden)

    Huansheng Yang

    Full Text Available Genetic selection strategies towards increased prolificacy have resulted in more and more increased littler size and incidences of impaired fetal development. Low birth weight (LBW piglets, with long-term alterations in structure, physiology and metabolism, have lower survival rates and poor growth performance. The aim of the study was to compare the plasma, liver and skeletal muscle contents of neutral amino acids (NAA and the intestinal expression of NAA transporters between LBW and high birth weight (HBW suckling Huanjiang mini-piglets. Forty piglets with either LBW or HBW (20 piglets per group were sampled on day 0, 7, 14 and 21 of age to give 5 observations per day per group. The contents of NAA in plasma, liver and skeletal muscle were measured, and jejunal expression of transporters for NAA, including Slc6a19 (B(0AT1 and Slc1a5 (ASCT2, were determined by real-time RT-PCR and Western Blot, respectively. Results showed that the suckling piglets with LBW had higher contents of Thr, Ser, Gly, Ala, Val, Met, Ile, Leu, Tyr, Phe and Pro in liver, and Gly in skeletal muscle, whereas lower contents of Met, Ser and Ala in plasma when compared with the HBW littermates. Consistent with the content differences in plasma NAA, the jejunal expression profiles of both Slc6a19 (B(0AT1 and Slc1a5 (ASCT2 in the LBW piglets were lower in compared with the HBW littermates during the early suckling period. These findings suggested that intestinal dysfunction in the LBW piglets may be one of the reasons in altered physiology and metabolism states of other organs, which result in lower survival and growth rate.

  11. Role of Branched-Chain Amino Acid Transport in Bacillus subtilis CodY Activity

    OpenAIRE

    Belitsky, Boris R.

    2015-01-01

    CodY is a branched-chain amino acid-responsive transcriptional regulator that controls the expression of several dozen transcription units in Bacillus subtilis. The presence of isoleucine, valine, and leucine in the growth medium is essential for achieving high activity of CodY and for efficient regulation of the target genes. We identified three permeases—BcaP, BraB, and BrnQ—that are responsible for the bulk of isoleucine and valine uptake and are also involved in leucine uptake. At least o...

  12. Excitatory amino acid transporters tonically restrain nTS synaptic and neuronal activity to modulate cardiorespiratory function.

    Science.gov (United States)

    Matott, Michael P; Ruyle, Brian C; Hasser, Eileen M; Kline, David D

    2016-03-01

    The nucleus tractus solitarii (nTS) is the initial central termination site for visceral afferents and is important for modulation and integration of multiple reflexes including cardiorespiratory reflexes. Glutamate is the primary excitatory neurotransmitter in the nTS and is removed from the extracellular milieu by excitatory amino acid transporters (EAATs). The goal of this study was to elucidate the role of EAATs in the nTS on basal synaptic and neuronal function and cardiorespiratory regulation. The majority of glutamate clearance in the central nervous system is believed to be mediated by astrocytic EAAT 1 and 2. We confirmed the presence of EAAT 1 and 2 within the nTS and their colocalization with astrocytic markers. EAAT blockade withdl-threo-β-benzyloxyaspartic acid (TBOA) produced a concentration-related depolarization, increased spontaneous excitatory postsynaptic current (EPSC) frequency, and enhanced action potential discharge in nTS neurons. Solitary tract-evoked EPSCs were significantly reduced by EAAT blockade. Microinjection of TBOA into the nTS of anesthetized rats induced apneic, sympathoinhibitory, depressor, and bradycardic responses. These effects mimicked the response to microinjection of exogenous glutamate, and glutamate responses were enhanced by EAAT blockade. Together these data indicate that EAATs tonically restrain nTS excitability to modulate cardiorespiratory function.

  13. Effects of organic acids, amino acids and ethanol on the radio-degradation of patulin in an aqueous model system

    Energy Technology Data Exchange (ETDEWEB)

    Yun, Hyejeong [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Chonbuk, Jeongeup 580-185 (Korea, Republic of); Department of Food Science and Technology, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Lim, Sangyong [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Chonbuk, Jeongeup 580-185 (Korea, Republic of); Jo, Cheorun [Department of Animal Science and Biotechnology, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Chung, Jinwoo [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Chonbuk, Jeongeup 580-185 (Korea, Republic of); Kim, Soohyun [Glycomics Team, Korea Basic Science Institute, Daejeon 305-333 (Korea, Republic of); Kwon, Joong-Ho [Department of Food Science and Technology, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Kim, Dongho [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Chonbuk, Jeongeup 580-185 (Korea, Republic of)], E-mail: fungikim@kaeri.re.kr

    2008-06-15

    The effects of organic acids, amino acids, and ethanol on the radio-degradation of patulin by gamma irradiation in an aqueous model system were investigated. The patulin, dissolved in distilled water at a concentration of 50 ppm, was practically degraded by the gamma irradiation at the dose of 1.0 kGy, while 33% of the patulin remained in apple juice. In the aqueous model system, the radio-degradation of patulin was partially inhibited by the addition of organic acids, amino acids, and ethanol. The proportions of remaining patulin after irradiation with the dose of 1.0 kGy in the 1% solution of malic acid, citric acid, lactic acid, acetic acid, ascorbic acid, and ethanol were 31.4%, 2.3%, 31.2%, 6.1%, 50.8%, and 12.5%, respectively. During 30 days of storage, the remaining patulin was reduced gradually in the solution of ascorbic acid and malic acid compared to being stable in other samples. The amino acids, serine, threonine, and histidine, inhibited the radio-degradation of patulin. In conclusion, it was suggested that 1 kGy of gamma irradiation (recommended radiation doses for radicidation and/or quarantine in fruits) is effective for the reduction of patulin, but the nutritional elements should be considered because the radio-degradation effects are environment dependent.

  14. Dysfunction in macrophage toll-like receptor signaling caused by an inborn error of cationic amino acid transport.

    Science.gov (United States)

    Kurko, Johanna; Vähä-Mäkilä, Mari; Tringham, Maaria; Tanner, Laura; Paavanen-Huhtala, Sari; Saarinen, Maiju; Näntö-Salonen, Kirsti; Simell, Olli; Niinikoski, Harri; Mykkänen, Juha

    2015-10-01

    Amino acids, especially arginine, are vital for the well-being and activity of immune cells, and disruption of amino acid balance may weaken immunity and predispose to infectious and autoimmune diseases. We present here a model of an inborn aminoaciduria, lysinuric protein intolerance (LPI), in which a single mutation in y(+)LAT1 cationic amino acid transporter gene SLC7A7 leads to a multisystem disease characterized by immunological complications, life-threatening pulmonary alveolar proteinosis and nephropathy. Macrophages are suggested to play a central role in LPI in the development of these severe secondary symptoms. We thus studied the effect of the Finnish y(+)LAT1 mutation on monocyte-derived macrophages where toll-like receptors (TLRs) act as the key molecules in innate immune response against external pathogens. The function of LPI patient and control macrophage TLR signaling was examined by stimulating the TLR2/1, TLR4 and TLR9 pathways with their associated pathogen-associated molecular patterns. Downregulation in expression of TLR9, IRF7, IRF3 and IFNB1 and in secretion of IFN-α was detected, suggesting an impaired response to TLR9 stimulation. In addition, secretion of TNF-α, IL-12 and IL-1RA by TLR2/1 stimulation and IL-12 and IL-1RA by TLR4 stimulation was increased in the LPI patients. LPI macrophages secreted significantly less nitric oxide than control macrophages, whereas plasma concentrations of inflammatory chemokines CXCL8, CXCL9 and CXCL10 were elevated in the LPI patients. In conclusion, our results strengthen the relevance of macrophages in the pathogenesis of LPI and, furthermore, suggest that cationic amino acid transport plays an important role in the regulation of innate immune responses. PMID:26210182

  15. Expression profiles of the genes associated with metabolism and transport of amino acids and their derivatives in rat liver regeneration.

    Science.gov (United States)

    Xu, C S; Chang, C F

    2008-01-01

    Amino acids (AA) are components of protein and precursors of many important biological molecules. To address effects of the genes associated with metabolism and transport of AA and their derivatives during rat liver regeneration (LR), we firstly obtained the above genes by collecting databases data and retrieving related thesis, and then analyzed their expression profiles during LR using Rat Genome 230 2.0 array. The LR-associated genes were identified by comparing the gene expression difference between partial hepatectomy (PH) and sham-operation (SO) rat livers. It was approved that 134 genes associated with metabolism of AA and their derivatives and 26 genes involved in transport of them were LR-associated. The initially and totally expressing number of these genes occurring in initial phase of LR (0.5-4 h after PH), G0/G1 (4-6 h after PH), cell proliferation (6-66 h after PH), cell differentiation and structure-function reconstruction of liver tissue (72-168 h after PH) were respectively 76, 17, 79, 5 and 162, 89, 564, 195, illustrating that these LR-associated genes were initially expressed mainly in initial stage, and functioned in different phases. Frequencies of up-regulation and down-regulation of them being separately 564 and 357 demonstrated that genes up-regulated outnumbered those down-regulated. Categorization of their expression patterns into 22 types implied the diversity of cell physiological and biochemical activities. According to expression changes and patterns of the above-mentioned genes in LR, it was presumed that histidine biosynthesis in the metaphase and anaphase, valine metabolism in the anaphase, and metabolism of glutamate, glutamine, asparate, asparagine, methionine, alanine, leucine and aromatic amino acid almost were enhanced in the whole LR; as for amino acid derivatives, transport of neutral amino acids, urea, gamma-aminobutyric acid, betaine and taurine, metabolism of dopamine, heme, S-adenosylmethionine, thyroxine, and

  16. Quantitative amino acid profiling and stable isotopically labeled amino acid tracer enrichment used for in vivo human systemic and tissue kinetics measurements

    DEFF Research Database (Denmark)

    Bornø, Andreas; van Hall, Gerrit

    2014-01-01

    . The present study describes a new sensitive liquid chromatography tandem mass-spectrometry method quantifying 20 amino acids and their tracer(s) ([ring-(13)C6]/D5Phenylalanine) in human plasma and skeletal muscle specimens. Before analysis amino acids were extracted and purified via deprotonization...... curve correlations for amino acids were on average; r(2)=0.998. Interday accuracy for amino acids determined in spiked plasma was on average 97.3% and the coefficient of variation (CV) was 2.6%. The ([ring-(13)C6]/D5Phenylalanine) enrichment CV's for machine reproducibility in muscle tissue fluid......An important area within clinical functional metabolomics is in vivo amino acid metabolism and protein turnover measurements for which accurate amino acid concentrations and stable isotopically labeled amino acid enrichments are mandatory not the least when tissue metabolomics is determined...

  17. A new treatment for human malignant melanoma targeting L-type amino acid transporter 1 (LAT1): A pilot study in a canine model

    Energy Technology Data Exchange (ETDEWEB)

    Fukumoto, Shinya; Hanazono, Kiwamu [Veterinary Internal Medicine, Department of Small Animal Clinical Sciences, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501 (Japan); Fu, Dah-Renn; Endo, Yoshifumi; Kadosawa, Tsuyoshi [Veterinary Oncology, Department of Small Animal Clinical Sciences, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501 (Japan); Iwano, Hidetomo [Veterinary Biochemistry, Department of Basic Veterinary Medicine, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501 (Japan); Uchide, Tsuyoshi, E-mail: uchide@rakuno.ac.jp [Veterinary Internal Medicine, Department of Small Animal Clinical Sciences, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501 (Japan)

    2013-09-13

    Highlights: •LAT1 is highly expressed in tumors but at low levels in normal tissues. •We examine LAT1 expression and function in malignant melanoma (MM). •LAT1 expression in MM tissues and cell lines is higher than those in normal tissues. •LAT1 selective inhibitors inhibit amino acid uptake and cell growth in MM cells. •New chemotherapeutic protocols including LAT1 inhibitors are effective for treatment. -- Abstract: L-type amino acid transporter 1 (LAT1), an isoform of amino acid transport system L, transports branched or aromatic amino acids essential for fundamental cellular activities such as cellular growth, proliferation and maintenance. This amino acid transporter recently has received attention because of its preferential and up-regulated expression in a variety of human tumors in contrast to its limited distribution and low-level expression in normal tissues. In this study, we explored the feasibility of using LAT1 inhibitor as a new therapeutic agent for human malignant melanomas (MM) using canine spontaneous MM as a model for human MM. A comparative study of LAT expression was performed in 48 normal tissues, 25 MM tissues and five cell lines established from MM. The study observed LAT1 mRNA levels from MM tissues and cell lines that were significantly (P < 0.01) higher than in normal tissues. Additionally, MM with distant metastasis showed a higher expression than those without distant metastasis. Functional analysis of LAT1 was performed on one of the five cell lines, CMeC-1. [{sup 3}H]L-Leucine uptake and cellular growth activities in CMeC-1 were inhibited in a dose-dependent manner by selective LAT1 inhibitors (2-amino-2-norbornane-carboxylic acid, BCH and melphalan, LPM). Inhibitory growth activities of various conventional anti-cancer drugs, including carboplatin, cyclophosphamide, dacarbazine, doxorubicin, mitoxantrone, nimustine, vinblastine and vincristine, were significantly (P < 0.05) enhanced by combination use with BCH or LPM

  18. Involvement of the neutral amino acid transporter SLC6A15 and leucine in obesity-related phenotypes.

    Directory of Open Access Journals (Sweden)

    Jana Drgonova

    Full Text Available Brain pathways, including those in hypothalamus and nucleus of the solitary tract, influence food intake, nutrient preferences, metabolism and development of obesity in ways that often differ between males and females. Branched chain amino acids, including leucine, can suppress food intake, alter metabolism and change vulnerability to obesity. The SLC6A15 (v7-3 gene encodes a sodium-dependent transporter of leucine and other branched chain amino acids that is expressed by neurons in hypothalamus and nucleus of the solitary tract. We now report that SLC6A15 knockout attenuates leucine's abilities to reduce both: a intake of normal chow and b weight gain produced by access to a high fat diet in gender-selective fashions. We identify SNPs in the human SLC6A15 that are associated with body mass index and insulin resistance in males. These observations in mice and humans support a novel, gender-selective role for brain amino acid compartmentalization mediated by SLC6A15 in diet and obesity-associated phenotypes.

  19. Genome-wide survey and expression analysis of the amino acid transporter superfamily in potato (Solanum tuberosum L.).

    Science.gov (United States)

    Ma, Haoli; Cao, Xiaoli; Shi, Shandang; Li, Silu; Gao, Junpeng; Ma, Yuling; Zhao, Qin; Chen, Qin

    2016-10-01

    Amino acid transporters (AATs) are integral membrane proteins responsible for the transmembrane transport of amino acids and play important roles in various physiological processes of plants. However, there has not yet been a genome-wide overview of the StAAT gene family to date and only StAAP1 has been previously studied in potato. In this paper, a total of 72 StAATs were identified using a series of bioinformatics searches and classified into 12 subfamilies based on their phylogenetic relationship with known Arabidopsis and rice AATs. Chromosomal localization revealed their distribution on all 12 chromosomes. Nearly one-third of StAAT genes (23 of 72) were derived from gene duplication, among which tandem duplication made the greatest contribution to the expansion of the StAAT family. Motif analysis showed that the same subfamily had similar conserved motifs in both numbers and varieties. Moreover, high-throughput sequencing data was used to analyze the expression patterns of StAAT genes and was verified by quantitative real-time RT-PCR. The expression of StAAT genes exhibited both abundant and tissue-specific expression patterns, which might be connected to their functional roles in long- and short-distance transport. This study provided a comprehensive survey of the StAAT gene family, and could serve as a theoretical foundation for the further functional identification and utilization of family members. PMID:27289266

  20. Group I mGluR-Regulated Translation of the Neuronal Glutamate Transporter, Excitatory Amino Acid Carrier 1 (EAAC1)

    OpenAIRE

    Ross, John R.; Ramakrishnan, Hariharasubramanian; Porter, Brenda E.; Robinson, Michael B.

    2011-01-01

    Recently, we demonstrated that mRNA for the neuronal glutamate transporter, excitatory amino acid carrier 1 (EAAC1), is found in dendrites of hippocampal neurons in culture and in dendrites of hippocampal pyramidal cells after pilocarpine-induced status epilepticus (SE). We also showed that SE increased the levels of EAAC1 mRNA ~15-fold in synaptoneurosomes. In the present study, the effects of SE on the distribution EAAC1 protein in hippocampus were examined. In addition, the effects of Grou...

  1. Concentration and distribution of dissolved amino acids in a shallow hydrothermal system, Vulcano Island (Italy)

    Energy Technology Data Exchange (ETDEWEB)

    Svensson, E.; Skoog, A. [University of Connecticut, Groton, CT (United States). Dept. of Marine Sciences; Amend, J.P. [Washington University, St. Louis, MO (United States). Dept. of Earth and Planetary Sciences

    2004-09-01

    Hydrothermal systems are known to harbour a large number of microorganisms, but the organic chemical composition of the solution that comprises their potential substrate is largely unknown. Concentrations and distributions of dissolved free amino acids (DFAA) and dissolved combined amino acids (DCAA) were determined in fluids from the moderate-temperature (42-89{sup o}C), shallow hydrothermal system on the volcanically active island of Vulcano, Italy. The seven samples represent three different geological settings on the island; shallow ({approx} 1 m) submarine vents, geothermal wells, and seeps in heated beach sediments, in addition to ambient local seawater from the bay, Baia di Levante. All hydrothermal sites, with one exception, had TDAA concentrations that were 3-114 times higher than local seawater in Baia di Levante. There were large similarities in amino acid concentration and composition among samples from the same geological setting. The highest amino acid concentrations were found at sites with acidic and reducing conditions, which also had the largest freshwater component. An unusually high fraction of the TDAA pool was represented by DFAA (33-87%), possibly due to in situ acid hydrolysis of DCAA to DFAA. Both DFAA and DCAA concentrations were correlated to DOC, indicating similar source and sink functions for these pools. The yield of TDAA (TDAA-carbon as fraction of organic carbon) ranged from 2% to 25%, which is high compared with non-hydrothermal settings, and indicates high biological lability. The mole fraction of {beta}-alanine plus {gamma}-aminobutyric acid (% BALA + GABA) was 2-2.7% of TDAA, also indicating high biological lability. Owing to the high over-all amino acid concentrations, the high fraction of DFAAs, and the high biological lability of the organic matter, organic matter in general and amino acids specifically could represent significant carbon and energy sources for archaea and bacteria in this hydrothermal system. The clear

  2. 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...

  3. Amino acid analysis.

    Science.gov (United States)

    Crabb, J W; West, K A; Dodson, W S; Hulmes, J D

    2001-05-01

    Amino acid analysis (AAA) is one of the best methods to quantify peptides and proteins. Two general approaches to quantitative AAA exist, namely, classical postcolumn derivatization following ion-exchange chromatography and precolumn derivatization followed by reversed-phase HPLC (RP-HPLC). Excellent instrumentation and several specific methodologies are available for both approaches, and both have advantages and disadvantages. This unit focuses on picomole-level AAA of peptides and proteins using the most popular precolumn-derivatization method, namely, phenylthiocarbamyl amino acid analysis (PTC-AAA). It is directed primarily toward those interested in establishing the technology with a modest budget. PTC derivatization and analysis conditions are described, and support and alternate protocols describe additional techniques necessary or useful for most any AAA method--e.g., sample preparation, hydrolysis, instrument calibration, data interpretation, and analysis of difficult or unusual residues such as cysteine, tryptophan, phosphoamino acids, and hydroxyproline. PMID:18429107

  4. Agp2, a Member of the Yeast Amino Acid Permease Family, Positively Regulates Polyamine Transport at the Transcriptional Level

    KAUST Repository

    Aouida, Mustapha

    2013-06-03

    Agp2 is a plasma membrane protein of the Saccharomyces cerevisiae amino acid transporter family, involved in high-affinity uptake of various substrates including L-carnitine and polyamines. The discovery of two high affinity polyamine permeases, Dur3 and Sam3, prompted us to investigate whether Agp2 directly transports polyamines or acts instead as a regulator. Herein, we show that neither dur3? nor sam3? single mutant is defective in polyamine transport, while the dur3? sam3? double mutant exhibits a sharp decrease in polyamine uptake and an increased resistance to polyamine toxicity similar to the agp2? mutant. Studies of Agp2 localization indicate that in the double mutant dur3? sam3?, Agp2-GFP remains plasma membrane-localized, even though transport of polyamines is strongly reduced. We further demonstrate that Agp2 controls the expression of several transporter genes including DUR3 and SAM3, the carnitine transporter HNM1 and several hexose, nucleoside and vitamin permease genes, in addition to SKY1 encoding a SR kinase that positively regulates low-affinity polyamine uptake. Furthermore, gene expression analysis clearly suggests that Agp2 is a strong positive regulator of additional biological processes. Collectively, our data suggest that Agp2 might respond to environmental cues and thus regulate the expression of several genes including those involved in polyamine transport. © 2013 Aouida et al.

  5. Amino Acid transporters in cancer and their relevance to "glutamine addiction": novel targets for the design of a new class of anticancer drugs.

    Science.gov (United States)

    Bhutia, Yangzom D; Babu, Ellappan; Ramachandran, Sabarish; Ganapathy, Vadivel

    2015-05-01

    Tumor cells have an increased demand for amino acids because of their rapid proliferation rate. In addition to their need in protein synthesis, several amino acids have other roles in supporting cancer growth. There are approximately two-dozen amino acid transporters in humans, and tumor cells must upregulate one or more of these transporters to satisfy their demand for amino acids. If the transporters that specifically serve this purpose in tumor cells are identified, they can be targeted for the development of a brand new class of anticancer drugs; the logical basis of such a strategy would be to starve the tumor cells of an important class of nutrients. To date, four amino acid transporters have been found to be expressed at high levels in cancer: SLC1A5, SLC7A5, SLC7A11, and SLC6A14. Their induction occurs in a cancer type-specific manner with a direct or indirect involvement of the oncogene c-Myc. Further, these transporters are functionally coupled, thus maximizing their ability to promote cancer growth and chemoresistance. Progress has been made in preclinical studies, exploiting these transporters as drug targets in cancer therapy. These transporters also show promise in development of new tumor-imaging probes and in tumor-specific delivery of appropriately designed chemotherapeutic agents. PMID:25855379

  6. Identification of a Disulfide Bridge in Sodium-Coupled Neutral Amino Acid Transporter 2(SNAT2) by Chemical Modification.

    Science.gov (United States)

    Chen, Chen; Wang, Jiahong; Cai, Ruiping; Yuan, Yanmeng; Guo, Zhanyun; Grewer, Christof; Zhang, Zhou

    2016-01-01

    Sodium-coupled neutral amino acid transporter 2 (SNAT2) belongs to solute carrier 38 (SLC38) family of transporters, which is ubiquitously expressed in mammalian tissues and mediates transport of small, neutral amino acids, exemplified by alanine(Ala, A). Yet structural data on SNAT2, including the relevance of intrinsic cysteine residues on structure and function, is scarce, in spite of its essential roles in many tissues. To better define the potential of intrinsic cysteines to form disulfide bonds in SNAT2, mutagenesis experiments and thiol-specific chemical modifications by N-ethylmaleimide (NEM) and methoxy-polyethylene glycol maleimide (mPEG-Mal, MW 5000) were performed, with or without the reducing regent dithiothreitol (DTT) treatment. Seven single mutant transporters with various cysteine (Cys, C) to alanine (Ala, A) substitutions, and a C245,279A double mutant were introduced to SNAT2 with a hemagglutinin (HA) tag at the C-terminus. The results showed that the cells expressing C245A or C279A were labeled by one equivalent of mPEG-Mal in the presence of DTT, while wild-type or all the other single Cys to Ala mutants were modified by two equivalents of mPEG-Mal. Furthermore, the molecular weight of C245,279A was not changed in the presence or absence of DTT treatment. The results suggest a disulfide bond between Cys245 and Cys279 in SNAT2 which has no effect on cell surface trafficking, as well as transporter function. The proposed disulfide bond may be important to delineate proximity in the extracellular domain of SNAT2 and related proteins. PMID:27355203

  7. Liquid-liquid distribution of aromatic α-amino acids in multicomponent systems

    Science.gov (United States)

    Korenman, Ya. I.; Mokshina, N. Ya.; Pakhomova, O. A.

    2010-02-01

    Distribution coefficients and recovery factors of phenylalanine, tyrosine, and tryptophan are measured in extraction systems with butanol, pentanol, acetone, and ethyl acetate, their binary and ternary mixtures, and water-soluble polymers. Extraction conditions—extractant composition, salting-out agents, and pH—are optimized. Efficient systems providing maximum quantitative characteristics of the process of liquid-liquid distribution of aromatic α-amino acids are proposed.

  8. Radiolysis of Amino Acids in Outer Solar-System Ice Analogs

    Science.gov (United States)

    Gerakines, Perry A.; Hudson, Reggie L.

    2011-01-01

    Amino acids have been found in cometary dust particles and in the organic component of meteorites. These molecules, important for pre-biotic chemistry and for active biological systems, might be formed in cold planetary or interstellar environments and then delivered to H20-rich surfaces in the outer solar system. Many models for the availability of organic species on Earth and elsewhere depend on the ability of these molecules to survive in radiation-rich space environments. This poster presents results of O.8-MeV proton radiolysis of ice films at lS-140K. using infrared spectroscopy, the destruction rates of glycine, alanine, and phenylalanine have been determined for both pure films and those containing amino acids diluted in H2o. our results are discussed in terms of the survivability of these molecules in the icy surfaces present in the outer solar system and the possibility of their detection by instruments on board the New Horizons spacecraft

  9. γ-氨基丁酸转运体与癫(癎)%γ-amino butyric acid transporter and epilepsy

    Institute of Scientific and Technical Information of China (English)

    董文涛

    2011-01-01

    根据γ-氨基丁酸转运体(γ-amino butyric acid transporter,GAT)5种不同亚型的脑区及亚细胞分布特点,GAT1和GAT3两者与癫(癎)的发生和发展关系最为密切.GAT表达异常或功能受损是癫(癎)发作时神经元高兴奋性的原因之一.γ-氨基丁酸能抑制性回路减少及其表达的GAT下降,原发性GAT表达上调,是癫(癎)发生的反应性改变或者癫(癎)发生的原因.%According to 5 different subtypes of γ-amino butyric acid transporter(GAT)in brain regions and subcellular distribution.GAT1 and GAT3 are closely related with occurrence and development of epilepsy.The abnormal expression of GAT or their function damaged contribute to hyperexcitable neurons In seizures.GABAergic inhibit circuit reduces and the down-regulation of GAT expression,primary up-regulation of GAT expression is a reactive changes or cause of epilepsy.

  10. Postprandial fate of amino acids: adaptation to molecular forms

    NARCIS (Netherlands)

    Nolles, J.A.

    2006-01-01

    During the postprandial phase dietary proteins are digested to peptides and amino acids and absorbed. Once absorbed the peptides are further hydrolyzed to amino acids and transported to the tissues. These amino acids are largely incorporated into body proteins. Not all amino acids are, however, inco

  11. Lipid Peroxidation Inhibitation Activity of Maillard Reaction Products Derived from Sugar-amino Acid Model Systems

    Directory of Open Access Journals (Sweden)

    Nanjing Zhong

    2015-08-01

    Full Text Available The present study aimed to evaluate the lipid peroxidation inhibitation activity of Maillard Reaction Products (MRPs derived from sugar (glucose, fructose, lactose and maltose and 18 amino acid model systems in soybean oil. MRPs were produced by heating at 130°C for 2 h. Of the 18 amino acids-fructose model systems studied, MRPs derived from fructose-leucine, fructose-methionine, fructose-phenylalanine and fructose-isoleucine model sytems showed high lipid peroxidation inhibitation activity and best performance was observed from fructose-phenylalanine MRPs. Interestingly, glucose-phenylalanine MRPs also exhibited high inhibitation activity and inhibitation activity of both glucose-phenylalanine and fructose-phenylalanine MRPs exceeded 87% even with concentration at 1.1 wt % after 8 days storage.

  12. Maternal Protein Restriction in the Rat Inhibits Placental Insulin, mTOR, and STAT3 Signaling and Down-Regulates Placental Amino Acid Transporters

    OpenAIRE

    Rosario, Fredrick J.; Jansson, Nina; Kanai, Yoshikatsu; Prasad, Puttur D; Powell, Theresa L.; Jansson, Thomas

    2011-01-01

    The mechanisms underlying reduced fetal growth in response to maternal protein restriction are not well established. Maternal levels of insulin, IGF-I, and leptin are decreased in rats fed a low protein (LP) diet. Because these hormones stimulate placental amino acid transporters in vitro, we hypothesized that maternal protein restriction inhibits placental leptin, insulin/IGF-I, and mammalian target of rapamycin signaling and down-regulates the expression and activity of placental amino acid...

  13. Transport of dibasic amino acids, cystine, and tryptophan by cultured human fibroblasts: absence of a defect in cystinuria and Hartnup disease

    Science.gov (United States)

    Groth, Ulrich; Rosenberg, Leon E.

    1972-01-01

    Transport of lysine, arginine, cystine, and tryptophan was studied in cultured skin fibroblasts from normal controls and from patients with cystinuria and Hartnup disease. Each of these amino acids was accumulated against concentration gradients by energy-dependent, saturable mechanisms. Lysine and arginine were each transported by two distinct processes which they shared with each other and with ornithine. In contrast, cystine was taken up by a different transport system with no demonstrable affinity for the dibasic amino acids. The time course and Michaelis-Menten kinetics of lysine and cystine uptake by cells from three cystinuric patients differed in no way from those found in control cells. Similarly, the characteristics of tryptophan uptake by cells from a child with Hartnup disease were identical to those noted in control cells. These findings indicate that the specific transport defects observed in gut and kidney in cystinuria and Hartnup disease are not expressed in cultured human fibroblasts, thus providing additional evidence of the important role that cellular differentiation plays in the regulation of expression of the human genome. PMID:5054467

  14. Graphdiyne as a promising material for detecting amino acids

    Science.gov (United States)

    Chen, Xi; Gao, Pengfei; Guo, Lei; Zhang, Shengli

    2015-11-01

    The adsorption of glycine, glutamic acid, histidine and phenylalanine on single-layer graphdiyne/ graphene is investigated by ab initio calculations. The results show that for each amino acid molecule, the adsorption energy on graphdiyne is larger than the adsorption energy on graphene and dispersion interactions predominate in the adsorption. Molecular dynamics simulations reveal that at room temperature the amino acid molecules keep migrating and rotating on graphdiyne surface and induce fluctuation in graphdiyne bandgap. Additionally, the photon absorption spectra of graphdiyne-amino-acid systems are investigated. We uncover that the presence of amino acid molecules makes the photon absorption peaks of graphdiyne significantly depressed and shifted. Finally, quantum electronic transport properties of graphdiyne-amino-acid systems are compared with the transport properties of pure graphdiyne. We reveal that the amino acid molecules induce distinct changes in the electronic conductivity of graphdiyne. The results in this paper reveal that graphdiyne is a promising two-dimensional material for sensitively detecting amino acids and may potentially be used in biosensors.

  15. Expression of apical Na(+)-L-glutamine co-transport activity, B(0)-system neutral amino acid co-transporter (B(0)AT1) and angiotensin-converting enzyme 2 along the jejunal crypt-villus axis in young pigs fed a liquid formula.

    Science.gov (United States)

    Yang, Chengbo; Yang, Xiaojian; Lackeyram, Dale; Rideout, Todd C; Wang, Zirong; Stoll, Barbara; Yin, Yulong; Burrin, Douglas G; Fan, Ming Z

    2016-06-01

    Gut apical amino acid (AA) transport activity is high at birth and during suckling, thus being essential to maintain luminal nutrient-dependent mucosal growth through providing AA as essential metabolic fuel, substrates and nutrient stimuli for cellular growth. Because system-B(0) Na(+)-neutral AA co-transporter (B(0)AT1, encoded by the SLC6A19 gene) plays a dominant role for apical uptake of large neutral AA including L-Gln, we hypothesized that high apical Na(+)-Gln co-transport activity, and B(0)AT1 (SLC6A19) in co-expression with angiotensin-converting enzyme 2 (ACE2) were expressed along the entire small intestinal crypt-villus axis in young animals via unique control mechanisms. Kinetics of Na(+)-Gln co-transport activity in the apical membrane vesicles, prepared from epithelial cells sequentially isolated along the jejunal crypt-villus axis from liquid formula-fed young pigs, were measured with the membrane potential being clamped to zero using thiocyanate. Apical maximal Na(+)-Gln co-transport activity was much higher (p < 0.05) in the upper villus cells than in the middle villus (by 29 %) and the crypt (by 30 %) cells, whereas Na(+)-Gln co-transport affinity was lower (p < 0.05) in the upper villus cells than in the middle villus and the crypt cells. The B(0)AT1 (SLC6A19) mRNA abundance was lower (p < 0.05) in the crypt (by 40-47 %) than in the villus cells. There were no significant differences in B(0)AT1 and ACE2 protein abundances on the apical membrane among the upper villus, the middle villus and the crypt cells. Our study suggests that piglet fast growth is associated with very high intestinal apical Na(+)-neutral AA uptake activities via abundantly co-expressing B(0)AT1 and ACE2 proteins in the apical membrane and by transcribing the B(0)AT1 (SLC6A19) gene in the epithelia along the entire crypt-villus axis. PMID:26984322

  16. Postprandial fate of amino acids: adaptation to molecular forms

    OpenAIRE

    Nolles, J.A.

    2006-01-01

    During the postprandial phase dietary proteins are digested to peptides and amino acids and absorbed. Once absorbed the peptides are further hydrolyzed to amino acids and transported to the tissues. These amino acids are largely incorporated into body proteins. Not all amino acids are, however, incorporated into body proteins part of these amino acids are oxidized, and can, thus, no longer be utilized to support protein metabolism in the body. The objective of this thesis was to increase the ...

  17. Fission yeast arrestin-related trafficking adaptor, Arn1/Any1, is ubiquitinated by Pub1 E3 ligase and regulates endocytosis of Cat1 amino acid transporter

    Directory of Open Access Journals (Sweden)

    Akio Nakashima

    2014-05-01

    Full Text Available The Tsc1–Tsc2 complex homologous to human tuberous sclerosis complex proteins governs amino acid uptake by regulating the expression and intracellular distribution of amino acid transporters in Schizosaccharomyces pombe. Here, we performed a genetic screening for molecules that are involved in amino acid uptake and found Arn1 (also known as Any1. Arn1 is homologous to ART1, an arrestin-related trafficking adaptor (ART in Saccharomyces cerevisiae, and contains a conserved arrestin motif, a ubiquitination site, and two PY motifs. Overexpression of arn1+ confers canavanine resistance on cells, whereas its disruption causes hypersensitivity to canavanine. We also show that Arn1 regulates endocytosis of the Cat1 amino acid transporter. Furthermore, deletion of arn1+ suppresses a defect of amino acid uptake and the aberrant Cat1 localization in tsc2Δ. Arn1 interacts with and is ubiquitinated by the Pub1 ubiquitin ligase, which is necessary to regulate Cat1 endocytosis. Cat1 undergoes ubiquitinations on lysine residues within the N-terminus, which are mediated, in part, by Arn1 to determine Cat1 localization. Correctively, Arn1 is an ART in S. pombe and contributes to amino acid uptake through regulating Cat1 endocytosis in which Tsc2 is involved.

  18. Preparation and investigation of tumor affinity, uptake kinetic and transport mechanism of iodine-123-labelled amino acid derivatives in human pancreatic carcinoma and glioblastoma cells

    Energy Technology Data Exchange (ETDEWEB)

    Samnick, Samuel E-mail: rassam@med-rz.uni-sb.de; Schaefer, Andrea; Siebert, Stefan; Richter, Sven; Vollmar, Brigitte; Kirsch, Carl-Martin

    2001-01-01

    In developing radioiodinated agents for pancreatic and brain tumor imaging by single photon emission tomography (SPET), we prepared p-amino-3-[{sup 123}I]iodo-l-phenylalanine (IAPA), p-[{sup 123}I]iodo-l-phenylalanine (IPA), L-8-[{sup 123}I]iodo-1,2,3,4-tetrahydro-7-hydroxyisoquinoline-3-carboxylic acid (ITIC) and L-3-[{sup 123}I]iodo-{alpha}-methyl-tyrosine (IMT) in radiochemical yields up to 95%, and we investigated their uptake in human pancreatic carcinoma and glioblastoma cells as well as the mechanisms promoting the tumor uptake. The radiopharmaceutical uptake into tumor cells was rapid (t{sub 1/2} {<=} 5 min) and temperature- and pH-dependent. The radioactivity concentration in tumor cells varied from 10 to 33% of the total activity (105-310 cpm/1000 cells) following a 30-min incubation at 37 deg. C (pH 7.4). In comparison, accumulation of the radiopharmaceuticals into normal brain and pancreatic tissue remained relatively low. Depolarizing the plasma membrane potential in high K{sup +} buffer significantly altered the radioactivity concentration in the tumor cells, suggesting that membrane potential plays a certain role in the cellular uptake. Competitive inhibition experiments with specific amino acid transport inhibitors indicated that the uptake of IAPA, IPA and IMT into human pancreatic carcinoma and glioblastoma cells is predominantly mediated by the L and ASC transport systems, while no substantial involvement of the transport system A in their tumor uptake could be demonstrated. In contrast, results of the present investigation indicated that ITIC is not taken up into tumor cells via the common neutral amino acid carrier systems, including the A, L and ASC system. Furthermore, preloading with naturally occurring L-amino acids failed to stimulate the cellular uptake of the radiopharmaceuticals. These data indicate that the investigated radiopharmaceuticals exhibit interesting characteristics with promise for in vivo tumor investigations to ascertain

  19. Cationic amino acid transporters and Salmonella Typhimurium ArgT collectively regulate arginine availability towards intracellular Salmonella growth.

    Directory of Open Access Journals (Sweden)

    Priyanka Das

    Full Text Available Cationic amino acid transporters (mCAT1 and mCAT2B regulate the arginine availability in macrophages. How in the infected cell a pathogen can alter the arginine metabolism of the host remains to be understood. We reveal here a novel mechanism by which Salmonella exploit mCAT1 and mCAT2B to acquire host arginine towards its own intracellular growth within antigen presenting cells. We demonstrate that Salmonella infected bone marrow derived macrophages and dendritic cells show enhanced arginine uptake and increased expression of mCAT1 and mCAT2B. We show that the mCAT1 transporter is in close proximity to Salmonella containing vacuole (SCV specifically by live intracellular Salmonella in order to access the macrophage cytosolic arginine pool. Further, Lysosome associated membrane protein 1, a marker of SCV, also was found to colocalize with mCAT1 in the Salmonella infected cell. The intra vacuolar Salmonella then acquire the host arginine via its own arginine transporter, ArgT for growth. The argT knockout strain was unable to acquire host arginine and was attenuated in growth in both macrophages and in mice model of infection. Together, these data reveal survival strategies by which virulent Salmonella adapt to the harsh conditions prevailing in the infected host cells.

  20. Function and expression of the proton-coupled amino acid transporter Slc36a1 along the rat gastrointestinal tract

    DEFF Research Database (Denmark)

    Broberg, M. L.; Holm, Rasmus Koldborg; Tønsberg, H;

    2012-01-01

    BACKGROUND AND PURPOSE: Intestinal absorption via membrane transporters may determine the pharmacokinetics of drug compounds. The hypothesis is that oral absorption of gaboxadol (4, 5, 6, 7-tetrahydroisoxazolo [5,4-c] pyridine-3-ol) in rats occurs via the proton-coupled amino acid transporter, r......PAT1 (encoded by the gene rSlc36a1). The aim is consequently to elucidate the in vivo role of rPAT1 in the absorption of gaboxadol from various intestinal segments. EXPERIMENTAL APPROACH: The absorption of gaboxadol was investigated following administration in four different intestinal segments....... The intestinal expression of rSlc36a1 mRNA was measured by quantitative real-time PCR (q-RT-PCR). Furthermore, the hPAT1-/rPAT1-mediated transport of gaboxadol or L-proline was studied in hPAT1-expressing X. laevis oocytes, Caco-2 cell monolayers and excised segments of the rat intestine. KEY RESULTS...

  1. Amino Acid Export in Plants: A Missing Link in Nitrogen Cycling

    Institute of Scientific and Technical Information of China (English)

    Sakiko Okumoto; Guillaume Pilot

    2011-01-01

    T The export of nutrients from source organs to parts of the body where they are required (e.g. sink organs) is a fundamental biological process. Export of amino acids, one of the most abundant nitrogen species in plant long-distance transport tissues (i.e. xylem and phloem), is an essential process for the proper distribution of nitrogen in the plant. Physiological studies have detected the presence of multiple amino acid export systems in plant cell membranes. Yet, surprisingly little is known about the molecular identity of amino acid exporters, partially due to the technical difficulties hampering the identification of exporter proteins. In this short review, we will summarize our current knowledge about amino acid export systems in plants. Several studies have described plant amino acid transporters capable of bi-directional, facilitative transport, reminiscent of activities identified by earlier physiological studies. Moreover, recent expansion in the number of available amino acid transporter sequences have revealed evolutionary relationships between amino acid exporters from other organisms with a number of uncharacterized plant proteins, some of which might also function as amino acid exporters. In addition, genes that may regulate export of amino acids have been discovered. Studies of these putative transporter and regulator proteins may help in understanding the elusive molecular mechanisms of amino acid export in plants.

  2. Maternal Factors Are Associated with the Expression of Placental Genes Involved in Amino Acid Metabolism and Transport.

    Directory of Open Access Journals (Sweden)

    Pricilla E Day

    Full Text Available Maternal environment and lifestyle factors may modify placental function to match the mother's capacity to support the demands of fetal growth. Much remains to be understood about maternal influences on placental metabolic and amino acid transporter gene expression. We investigated the influences of maternal lifestyle and body composition (e.g. fat and muscle content on a selection of metabolic and amino acid transporter genes and their associations with fetal growth.RNA was extracted from 102 term Southampton Women's Survey placental samples. Expression of nine metabolic, seven exchange, eight accumulative and three facilitated transporter genes was analyzed using quantitative real-time PCR.Increased placental LAT2 (p = 0.01, y+LAT2 (p = 0.03, aspartate aminotransferase 2 (p = 0.02 and decreased aspartate aminotransferase 1 (p = 0.04 mRNA expression associated with pre-pregnancy maternal smoking. Placental mRNA expression of TAT1 (p = 0.01, ASCT1 (p = 0.03, mitochondrial branched chain aminotransferase (p = 0.02 and glutamine synthetase (p = 0.05 was positively associated with maternal strenuous exercise. Increased glutamine synthetase mRNA expression (r = 0.20, p = 0.05 associated with higher maternal diet quality (prudent dietary pattern pre-pregnancy. Lower LAT4 (r = -0.25, p = 0.05 and aspartate aminotransferase 2 mRNA expression (r = -0.28, p = 0.01 associated with higher early pregnancy diet quality. Lower placental ASCT1 mRNA expression associated with measures of increased maternal fat mass, including pre-pregnancy BMI (r = -0.26, p = 0.01. Lower placental mRNA expression of alanine aminotransferase 2 associated with greater neonatal adiposity, for example neonatal subscapular skinfold thickness (r = -0.33, p = 0.001.A number of maternal influences have been linked with outcomes in childhood, independently of neonatal size; our finding of associations between placental expression of transporter and metabolic genes and maternal smoking

  3. Amino acid uptake in rust fungi.

    Science.gov (United States)

    Struck, Christine

    2015-01-01

    The plant pathogenic rust fungi colonize leaf tissue and feed off their host plants without killing them. Certain economically important species of different genera such as Melampsora, Phakopsora, Puccinia, or Uromyces are extensively studied for resolving the mechanisms of the obligate biotrophy. As obligate parasites rust fungi only can complete their life cycle on living hosts where they grow through the leaf tissue by developing an extended network of intercellular hyphae from which intracellular haustoria are differentiated. Haustoria are involved in key functions of the obligate biotrophic lifestyle: suppressing host defense responses and acquiring nutrients. This review provides a survey of rust fungi nitrogen nutrition with special emphasis on amino acid uptake. A variety of sequences of amino acid transporter genes of rust fungi have been published; however, transport activity of only three in planta highly up-regulated amino acid permeases have been characterized. Functional and immunohistochemical investigations have shown the specificity and localization of these transporters. Sequence data of various genome projects allowed identification of numerous rust amino acid transporter genes. An in silico analysis reveals that these genes can be classified into different transporter families. In addition, genetic and molecular data of amino acid transporters have provided new insights in the corresponding metabolic pathways.

  4. Amino acid decarboxylations produced by lipid-derived reactive carbonyls in amino acid mixtures.

    Science.gov (United States)

    Hidalgo, Francisco J; León, M Mercedes; Zamora, Rosario

    2016-10-15

    The formation of 2-phenylethylamine and phenylacetaldehyde in mixtures of phenylalanine, a lipid oxidation product, and a second amino acid was studied to determine the role of the second amino acid in the degradation of phenylalanine produced by lipid-derived reactive carbonyls. The presence of the second amino acid usually increased the formation of the amine and reduced the formation of the Strecker aldehyde. The reasons for this behaviour seem to be related to the α-amino group and the other functional groups (mainly amino or similar groups) present in the side-chain of the amino acid. These groups are suggested to modify the lipid-derived reactive carbonyl but not the reaction mechanism because the Ea of formation of both 2-phenylethylamine and phenylacetaldehyde remained unchanged in all studied systems. All these results suggest that the amine/aldehyde ratio obtained by amino acid degradation can be modified by adding free amino acids during food formulation. PMID:27173560

  5. Research for amino acids in lunar samples.

    Science.gov (United States)

    Gehrke, C. W.; Zumwalt, R. W.; Kuo, K.; Rash, J. J.; Aue , W. A.; Stalling, D. L.; Kvenvolden, K. A.; Ponnamperuma, C.

    1972-01-01

    The study was primarily directed toward the examination of Apollo 14 lunar fines for indigenous amino acids or materials which could be converted to amino acids on hydrolysis with 6 N hydrochloric acid. Initial experiments were conducted to confirm the integrity of the derivatization reactions and reagents, and to optimize the gas-liquid chromatographic (GLC) instrumental and chromatographic system for the separation and flame ionization detection of the amino acid derivatives. In studies on the recovery of amino acids added to lunar fines, low recoveries were obtained when 10 ng of each amino acid were added to 50 mg of virgin fines, but the subsequent addition of 50 ng of each to the previously extracted sample resulted in much higher recoveries.

  6. Microfluidics in amino acid analysis.

    Science.gov (United States)

    Pumera, Martin

    2007-07-01

    Microfluidic devices have been widely used to derivatize, separate, and detect amino acids employing many different strategies. Virtually zero-dead volume interconnections and fast mass transfer in small volume microchannels enable dramatic increases in on-chip derivatization reaction speed, while only minute amounts of sample and reagent are needed. Due to short channel path, fast subsecond separations can be carried out. With sophisticated miniaturized detectors, the whole analytical process can be integrated on one platform. This article reviews developments of lab-on-chip technology in amino acid analysis, it shows important design features such as sample preconcentration, precolumn and postcolumn amino acid derivatization, and unlabeled and labeled amino acid detection with focus on advanced designs. The review also describes important biomedical and space exploration applications of amino acid analysis on microfluidic devices. PMID:17542043

  7. Mislocalization of the exitatory amino-acid transporters (EAATs) in human astrocytoma and non-astrocytoma cancer cells: effect of the cell confluence

    OpenAIRE

    Varini Karine; Benzaria Amal; Taïeb Nadira; Di Scala Coralie; Azmi Amanda; Graoudi Soraya; Maresca Marc

    2012-01-01

    Abstract Background Astrocytomas are cancers of the brain in which high levels of extracellular glutamate plays a critical role in tumor growth and resistance to conventional treatments. This is due for part to a decrease in the activity of the glutamate transporters, i.e. the Excitatory Amino Acid Transporters or EAATs, in relation to their nuclear mislocalization in astrocytoma cells. Although non-astrocytoma cancers express EAATs, the localization of EAATs and the handling of L-glutamate i...

  8. Constitutive Tor2 Activity Promotes Retention of the Amino Acid Transporter Agp3 at Trans-Golgi/Endosomes in Fission Yeast.

    Directory of Open Access Journals (Sweden)

    Qingbin Liu

    Full Text Available Amino acid transporters are located at specific subcellular compartments, and their localizations are regulated by the extracellular availability of amino acids. In yeast, target of rapamycin (TOR activation induces the internalization of amino acid transporters located at the plasma membrane. However, whether and how TOR signaling regulates other amino acid transporters located at intracellular compartments remains unknown. Here, we demonstrate that in the fission yeast, the TOR inhibitor Torin-1 induces the transfer of several yellow fluorescent protein (YFP-fused intracellular amino acid transporters, including Agp3, Isp5, Aat1, and Put4, from trans-Golgi/endosomes into the vacuoles. By contrast, the localizations of YFP-fused Can1, Fnx1, and Fnx2 transporter proteins were unaffected upon Torin-1 treatment. There are two TOR isoforms in fission yeast, Tor1 and Tor2. Whereas tor1 deletion did not affect the Torin-1-induced transfer of Agp3-YFP, Tor2 inhibition using a temperature-sensitive mutant induced the transfer of Agp3-YFP to the vacuolar lumen, similar to the effects of Torin-1 treatment. Tor2 inhibition also induced the transfer of the YFP-fused Isp5, Aat1, and Put4 transporter proteins to the vacuoles, although only partial transfer of the latter two transporters was observed. Under nitrogen depletion accompanied by reduced Tor2 activity, Agp3-YFP was transferred from the trans-Golgi/endosomes to the plasma membrane and then to the vacuoles, where it was degraded by the vacuolar proteases Isp6 and Psp3. Mutants with constitutively active Tor2 showed delayed transfer of Agp3-YFP to the plasma membrane upon nitrogen depletion. Cells lacking Tsc2, a negative regulator of Tor2, also showed a delay in this process in a Tor2-dependent manner. Taken together, these findings suggest that constitutive Tor2 activity is critical for the retention of amino acid transporters at trans-Golgi/endosomes. Moreover, nitrogen depletion suppresses Tor2

  9. Amino Acid Metabolism of Thermoanaerobacter Strain AK90: The Role of Electron-Scavenging Systems in End Product Formation

    Directory of Open Access Journals (Sweden)

    Sean Michael Scully

    2015-01-01

    Full Text Available The catabolism of the 20 amino acids by Thermoanaerobacter strain AK90 (KR007667 was investigated under three different conditions: as single amino acids without an electron-scavenging system, in the presence of thiosulfate, and in coculture with a hydrogenotrophic methanogen. The strain degraded only serine without an alternative electron acceptor but degraded 11 amino acids (alanine, cysteine, isoleucine, leucine, lysine, methionine, phenylalanine, serine, threonine, tyrosine, and valine under both of the electron-scavenging systems investigated. Acetate was the dominant end product from alanine, cysteine, lysine, serine, and threonine under electron-scavenging conditions. The branched-chain amino acids, isoleucine, leucine, and valine, were degraded to their corresponding fatty acids under methanogenic conditions and to a mixture of their corresponding fatty acids and alcohols in the presence of thiosulfate. The partial pressure of hydrogen seems to be of importance for the branched-chain alcohol formation. This was suggested by low but detectable hydrogen concentrations at the end of cultivation on the branched-chain amino acid in the presence of thiosulfate but not when cocultured with the methanogen. A more detailed examination of the role of thiosulfate as an electron acceptor was performed with Thermoanaerobacter ethanolicus (DSM 2246 and Thermoanaerobacter brockii (DSM 1457.

  10. Mutation of G234 amino acid residue in candida albicans drug-resistance-related protein Rta2p is associated with fluconazole resistance and dihydrosphingosine transport.

    Science.gov (United States)

    Zhang, Shi-Qun; Miao, Qi; Li, Li-Ping; Zhang, Lu-Lu; Yan, Lan; Jia, Yu; Cao, Yong-Bing; Jiang, Yuan-Ying

    2015-01-01

    Widespread and repeated use of azoles has led to the rapid development of drug resistance in Candida albicans. Our previous study found Rta2p, a membrane protein with 7 transmembrane domains, was involved in calcineurin-mediated azole resistance and sphingoid long-chain base release in C. albicans. Conserved amino acids in the transmembrane domain of Rta2p were subjected to site-directed mutagenesis. The sensitivity of C. albicans to fluconazole in vitro was examined by minimum inhibitory concentration and killing assay, and the therapeutic efficacy of fluconazole in vivo was performed by systemic mice candidiasis model. Furthermore, dihydrosphingosine transport activity was detected by NBD labeled D-erythro-dihydrosphingosine uptake and release assay, and the sensitivity to sphingolipid biosynthesis inhibitors. We successfully constructed 14 mutant strains of Rta2p, screened them by minimum inhibitory concentration and found Ca(2+) did not completely induce fluconazole resistance with G158E and G234S mutations. Furthermore, we confirmed that G234S mutant enhanced the therapeutic efficacy of fluconazole against systemic candidiasis and significantly increased the accumulation of dihydrosphingosine by decreasing its release. However, G158E mutant didn't affect drug therapeutic efficacy in vivo and dihydrosphingosine transport in C. albicans. G234 of Rta2p in C. albicans is crucial in calcineurin-mediated fluconazole resistance and dihydrosphingosine transport. PMID:26220356

  11. Structural calibration of the rates of amino acid evolution in a search for Darwin in drifting biological systems.

    Science.gov (United States)

    Toft, Christina; Fares, Mario A

    2010-10-01

    In the last two decades, many reports of proteins under positive selection have brought the neutral theory into question. However, the methods used to detect selection have ignored the evolvability of amino acids within proteins, which is fundamental to distinguishing positive selection from the relaxed constraints caused by genetic drift. Disentangling these two counterbalancing forces is essential to test the neutral theory. Here, we calibrate rates of amino acid divergence by using structural information from the full set of crystallized proteins in bacteria. In agreement with previous reports, we show that rates of amino acid evolution correlate negatively with the number of per-amino acid atomic interactions. Calibration of the rates of evolution allows identifying signatures of selection in biological systems that evolve under strong genetic drift, such as endosymbiotic bacteria. Application of this method identifies different rates and dynamics of evolution for highly connected amino acids in the structure compared with sparsely connected ones. We also unearth patterns of Darwinian selection in fundamental cellular proteins in endosymbiotic bacteria including the cochaperonin GroES, ribosomal proteins, proteins involved in cell cycle control, DNA-binding proteins, and proteins involved in DNA replication and repair. This is, to our knowledge, the first attempt to distinguish adaptive evolution from relaxed constraints in biological systems under genetic drift.

  12. Weekly intra-amniotic IGF-1 treatment increases growth of growth-restricted ovine fetuses and up-regulates placental amino acid transporters.

    Directory of Open Access Journals (Sweden)

    Jibran A Wali

    Full Text Available Frequent treatment of the growth-restricted (IUGR ovine fetus with intra-amniotic IGF-1 increases fetal growth. We aimed to determine whether increased growth was maintained with an extended dosing interval and to examine possible mechanisms. Pregnant ewes were allocated to three groups: Control, and two IUGR groups (induced by placental embolization treated with weekly intra-amniotic injections of either saline (IUGR or 360 µg IGF-1 (IGF1. IUGR fetuses were hypoxic, hyperuremic, hypoglycemic, and grew more slowly than controls. Placental glucose uptake and SLC2A1 (GLUT2 mRNA levels decreased in IUGR fetuses, but SLC2A3 (GLUT3 and SLC2A4 (GLUT4 levels were unaffected. IGF-1 treatment increased fetal growth rate, did not alter uterine blood flow or placental glucose uptake, and increased placental SLC2A1 and SLC2A4 (but not SLC2A3 mRNA levels compared with saline-treated IUGR animals. Following IGF-1 treatment, placental mRNA levels of isoforms of the system A, y(+, and L amino acid transporters increased 1.3 to 5.0 fold, while the ratio of phosphorylated-mTOR to total mTOR also tended to increase. Weekly intra-amniotic IGF-1 treatment provides a promising avenue for intra-uterine treatment of IUGR babies, and may act via increased fetal substrate supply, up-regulating placental transporters for neutral, cationic, and branched-chain amino acids, possibly via increased activation of the mTOR pathway.

  13. Low-protein amino acid-supplemented diets for growing pigs: effect on expression of amino acid transporters, serum concentration, performance, and carcass composition.

    Science.gov (United States)

    Morales, A; Buenabad, L; Castillo, G; Arce, N; Araiza, B A; Htoo, J K; Cervantes, M

    2015-05-01

    Pigs fed protein-bound AA appear to have a higher abundance of AA transporters for their absorption in the jejunum compared with the duodenum. However, there is limited data about the effect of dietary free AA, readily available in the duodenum, on the duodenal abundance of AA transporters and its impact on pig performance. Forty-eight pigs (24.3 kg initial BW) distributed in 4 treatments were used to evaluate the effect of the CP level and form (free vs. protein bound) in which AA are added to diets on the expression of AA transporters in the 3 small intestine segments, serum concentration of AA, and performance. Dietary treatments based on wheat and soybean meal (SBM) were 1) low-CP (14%) diet supplemented with L-Lys, L-Thr, DL-Met, L-Leu, L-Ile, L-Val, L-His, L-Trp, and L-Phe (LPAA); 2) as in the LPAA but with added L-Gly as a N source (LPAA+N); 3) intermediate CP content (16%) supplemented with L-Lys HCl, L-Thr, and DL-Met (MPAA); and 4) high-CP (22%) diet (HP) without free AA. At the end of the experiment, 8 pigs from LPAA and HP were sacrificed to collect intestinal mucosa and blood samples and to dissect the carcasses. There were no differences in ADG, ADFI, G:F, and weights of carcass components and some visceral organs between treatments. Weights of the large intestine and kidney were higher in HP pigs (P protein in HP wheat-SBM diets without affecting pig performance; nonessential N does not seem to be limiting in very low-protein wheat-SBM diets for growing pigs. Also, the inclusion of free AA in the diet appears to affect their serum concentration and the expression of the AA transporter b0,+ in the duodenum of pigs.

  14. Comparative evaluation of transport mechanisms of trans-1-amino-3-[¹⁸F]fluorocyclobutanecarboxylic acid and L-[methyl-¹¹C]methionine in human glioma cell lines.

    Science.gov (United States)

    Ono, Masahiro; Oka, Shuntaro; Okudaira, Hiroyuki; Schuster, David M; Goodman, Mark M; Kawai, Keiichi; Shirakami, Yoshifumi

    2013-10-16

    Positron emission tomography (PET) with amino acid tracers is useful for the visualization and assessment of therapeutic effects on gliomas. Our purpose is to elucidate the transport mechanisms of trans-1-amino-3-[¹⁸F]fluorocyclobutanecarboxylic acid (anti-[¹⁸F]FACBC) and L-[methyl-¹¹C]methionine ([¹¹C]Met) in normal human astrocytes (NHA), low-grade (Hs683, SW1088), and high-grade (U87MG, T98G) human glioma cell lines. Because the short half-lives of fluorine-18 and carbon-11 are inconvenient for in vitro experiments, trans-1-amino-3-fluoro[1-¹⁴C]cyclobutanecarboxylic acid (anti-[¹⁴C]FACBC) and L-[methyl-¹⁴C]methionine ([¹⁴C]Met) were used instead of the PET tracers. Time-course uptake experiments showed that uptake of anti-[¹⁴C]FACBC was 1.4-2.6 times higher than that of [¹⁴C]Met in NHA and low-grade glioma cells, and was almost equal to that of [¹⁴C]Met in high-grade glioma cells. To identify the amino acid transporters (AATs) involved in the transport of anti-[¹⁴C]FACBC and [¹⁴C]Met, we carried out competitive inhibition experiments using synthetic/naturally-occurring amino acids as inhibitors. We found that anti-[¹⁴C]FACBC uptake in the presence of Na⁺ was strongly inhibited by L-glutamine and L-serine (the substrates for ASC system AATs), whereas L-phenylalanine and 2-amino-bicyclo[2,2,1]heptane-2-carboxylic acid (BCH, the substrates for L system AATs) robustly inhibited Na⁺-independent anti-[¹⁴C]FACBC uptake. Regardless of Na⁺, [¹⁴C]Met uptake was inhibited strongly by L-phenylalanine and BCH. Moreover, the exchange transport activity of L-glutamine for anti-[¹⁴C]FACBC was stronger than that of BCH in the presence of Na⁺, whereas that for [¹⁴C]Met was almost equal to BCH. These results demonstrate that ASC and L are important transport systems for anti-[¹⁸F]FACBC uptake, while system L is predominantly involved in [¹¹C]Met transport in human astrocytes and glioma cells.

  15. Amino Acid Stability in the Early Oceans

    Science.gov (United States)

    Parker, E. T.; Brinton, K. L.; Burton, A. S.; Glavin, D. P.; Dworkin, J. P.; Bada, J. L.

    2015-01-01

    It is likely that a variety of amino acids existed in the early oceans of the Earth at the time of the origin and early evolution of life. "Primordial soup", hydrothermal vent, and meteorite based processes could have contributed to such an inventory. Several "protein" amino acids were likely present, however, based on prebiotic synthesis experiments and carbonaceous meteorite studies, non-protein amino acids, which are rare on Earth today, were likely the most abundant. An important uncertainty is the length of time these amino acids could have persisted before their destruction by abiotic and biotic processes. Prior to life, amino acid concentrations in the oceans were likely regulated by circulation through hydro-thermal vents. Today, the entire ocean circulates through vent systems every 10(exp 7) years. On the early Earth, this value was likely smaller due to higher heat flow and thus marine amino acid life-time would have been shorter. After life, amino acids in the oceans could have been assimilated by primitive organisms.

  16. Analysis of the LIV System of Campylobacter jejuni Reveals Alternative Roles for LivJ and LivK in Commensalism beyond Branched-Chain Amino Acid Transport

    OpenAIRE

    Ribardo, Deborah A.; Hendrixson, David R.

    2011-01-01

    Campylobacter jejuni is a leading cause of diarrheal disease in humans and an intestinal commensal in poultry and other agriculturally important animals. These zoonotic infections result in significant amounts of C. jejuni present in the food supply to contribute to disease in humans. We previously found that a transposon insertion in Cjj81176_1038, encoding a homolog of the Escherichia coli LivJ periplasmic binding protein of the leucine, isoleucine, and valine (LIV) branched-chain amino aci...

  17. Dietary protein effects on growth performance, carcass traits and expression of selected jejunal peptide and amino acid transporters in broiler chickens

    OpenAIRE

    A Corzo; II RE Loar; MT Kidd; SC Burgess

    2011-01-01

    The effect of dietary protein on growth, carcass traits and some specific intestinal intestinal peptide and amino acid transporters in broiler chickens was studied. Birds received a common pre-test diet, and were subsequently fed either a standard positive control diet (PC) or a reduced CP diet (RCP) from 21 to 42 d of age. Growth was negatively impacted with feeding of RCP as manifested by an increase in feed consumption and feed conversion ratio. Carcass traits also showed evidence of negat...

  18. Amino Acid Degradation after Meteoritic Impact Simulation

    Science.gov (United States)

    Bertrand, M.; Westall, F.; vanderGaast, S.; Vilas, F.; Hoerz, F.; Barnes, G.; Chabin, A.; Brack, A.

    2008-01-01

    Amino acids are among the most important prebiotic molecules as it is from these precursors that the building blocks of life were formed [1]. Although organic molecules were among the components of the planetesimals making up the terrestrial planets, large amounts of primitive organic precursor molecules are believed to be exogenous in origin and to have been imported to the Earth via micrometeorites, carbonaceous meteorites and comets, especially during the early stages of the formation of the Solar System [1,2]. Our study concerns the hypothesis that prebiotic organic matter, present on Earth, was synthesized in the interstellar environment, and then imported to Earth by meteorites or micrometeorites. We are particularly concerned with the formation and fate of amino acids. We have already shown that amino acid synthesis is possible inside cometary grains under interstellar environment conditions [3]. We are now interested in the effects of space conditions and meteoritic impact on these amino acids [4-6]. Most of the extraterrestrial organic molecules known today have been identified in carbonaceous chondrite meteorites [7]. One of the components of these meteorites is a clay with a composition close to that of saponite, used in our experiments. Two American teams have studied the effects of impact on various amino acids [8,9]. [8] investigated amino acids in saturated solution in water with pressure ranges between 5.1 and 21 GPa and temperature ranges between 412 and 870 K. [9] studied amino acids in solid form associated with and without minerals (Murchison and Allende meteorite extracts) and pressure ranges between 3 and 30 GPa. In these two experiments, the amino acids survived up to 15 GPa. At higher pressure, the quantity of preserved amino acids decreases quickly. Some secondary products such as dipeptides and diketopiperazins were identified in the [8] experiment.

  19. Genetically encoded fluorescent coumarin amino acids

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jiangyun (San Diego, CA); Xie, Jianming (San Diego, CA); Schultz, Peter G. (La Jolla, CA)

    2012-06-05

    The invention relates to orthogonal pairs of tRNAs and aminoacyl-tRNA synthetases that can incorporate the coumarin unnatural amino acid L-(7-hydroxycoumarin-4-yl)ethylglycine into proteins produced in eubacterial host cells such as E. coli. The invention provides, for example but not limited to, novel orthogonal synthetases, methods for identifying and making the novel synthetases, methods for producing proteins containing the unnatural amino acid L-(7-hydroxycoumarin-4-yl)ethylglycine and related translation systems.

  20. Genetically encoded fluorescent coumarin amino acids

    Science.gov (United States)

    Wang, Jiangyun; Xie, Jianming; Schultz, Peter G.

    2010-10-05

    The invention relates to orthogonal pairs of tRNAs and aminoacyl-tRNA synthetases that can incorporate the coumarin unnatural amino acid L-(7-hydroxycoumarin-4-yl) ethylglycine into proteins produced in eubacterial host cells such as E. coli. The invention provides, for example but not limited to, novel orthogonal synthetases, methods for identifying and making the novel synthetases, methods for producing proteins containing the unnatural amino acid L-(7-hydroxycoumarin-4-yl)ethylglycine and related translation systems.

  1. Kinetic parameters of oscillating reaction of amino acid-BrO-3-Mn2+-H2SO4-acetone system

    Institute of Scientific and Technical Information of China (English)

    LI Zongxiao; YUAN Chunlan; NIE Fei

    2005-01-01

    The oscillating behavior of thirteen amino acids [leucine (Leu), threonine (Thr), arginine (Arg), lysine (Lys), histidine (His), alanine (Ala), glutamine (Glu), glycine (Gly), methionine (Met), cystine (Cys), tryptophan (Trp), serine (Ser) and tyrosine (Tyr)] in amino acid--Mn2+-H2SO4-acetone system is studied by using a potentiometric determination. With the help of the oscillatory induction period and oscillation period obtained by the oscillating wave, and Arrhenius equation, the kinetic parameters [the apparent activation energy (E) and pre-exponential constant (A)] and rate constant (k) of the above-mentioned oscillating reaction are estimated.

  2. L-Glutamate supplementation improves small intestinal architecture and enhances the expressions of jejunal mucosa amino acid receptors and transporters in weaning piglets.

    Directory of Open Access Journals (Sweden)

    Meng Lin

    Full Text Available L-Glutamate is a major oxidative fuel for the small intestine. However, few studies have demonstrated the effect of L-glutamate on the intestinal architecture and signaling of amino acids in the small intestine. The aim of this study was to investigate the effects of dietary L-glutamate supplementation on the intestinal architecture and expressions of jejunal mucosa amino acid receptors and transporters in weaning piglets. A total of 120 weaning piglets aged 35 ± 1 days with an average body weight at 8.91 ± 0.45 kg were randomly allocated to two treatments with six replicates of ten piglets each, fed with diets containing 1.21% alanine, or 2% L-glutamate. L-Glutamate supplementation increased the activity of glutamate oxaloacetate transaminase (GOT in the jejunal mucosa. Also, the mRNA expression level of jejunal mucosa glutamine synthetase (GS was increased by L-glutamate supplementation. The height of villi in duodenal and jejunal segments, and the relative mRNA expression of occludin and zonula occludens protein-1 (ZO-1 in jejunal mucosa were increased by dietary L-glutamate supplementation. L-Glutamate supplementation increased plasma concentrations of glutamate, arginine, histidine, isoleucine, leucine, methionine, phenylalanine and threonine. L-Glutamate supplementation also increased the relative mRNA expression of the jejunal mucosa Ca(2+-sensing receptor (CaR, metabotropic glutamate receptor 1 (mGluR1 and metabotropic glutamate receptor 4 (mGluR4, and neutral amino acid transporter B(0-like (SLC1A5 in the jejunal mucosa. These findings suggest that dietary addition of 2% L-glutamate improves the intestinal integrity and influences the expression of amino acid receptors and transporters in the jejunum of weaning, which is beneficial for the improvement of jejunal nutrients for digestion and absorption.

  3. Prolactin and the dietary protein/carbohydrate ratio regulate the expression of SNAT2 amino acid transporter in the mammary gland during lactation.

    Science.gov (United States)

    Velázquez-Villegas, Laura A; López-Barradas, Adriana M; Torres, Nimbe; Hernández-Pando, Rogelio; León-Contreras, Juan Carlos; Granados, Omar; Ortíz, Victor; Tovar, Armando R

    2015-05-01

    The sodium coupled neutral amino acid transporter 2 (SNAT2/SAT2/ATA2) is expressed in the mammary gland (MG) and plays an important role in the uptake of alanine and glutamine which are the most abundant amino acids transported into this tissue during lactation. Thus, the aim of this study was to assess the amount and localization of SNAT2 before delivery and during lactation in rat MG, and to evaluate whether prolactin and the dietary protein/carbohydrate ratio might influence SNAT2 expression in the MG, liver and adipose tissue during lactation. Our results showed that SNAT2 protein abundance in the MG increased during lactation and this increase was maintained along this period, while 24 h after weaning it tended to decrease. To study the effect of prolactin on SNAT2 expression, we incubated MG explants or T47D cells transfected with the SNAT2 promoter with prolactin, and we observed in both studies an increase in the SNAT2 expression or promoter activity. Consumption of a high-protein/low carbohydrate diet increased prolactin concentration, with a concomitant increase in SNAT2 expression not only in the MG during lactation, but also in the liver and adipose tissue. There was a correlation between SNAT2 expression and serum prolactin levels depending on the amount of dietary protein/carbohydrate ratio consumed. These findings suggest that prolactin actively supports lactation providing amino acids to the gland through SNAT2 for the synthesis of milk proteins.

  4. The relationship between gene expression of cationic and neutral amino acid transporters in the small intestine of chick embryos and chick breed, development, sex, and egg amino acid concentration.

    Science.gov (United States)

    Zeng, P L; Li, X G; Wang, X Q; Zhang, D X; Shu, G; Luo, Q B

    2011-11-01

    This study was conducted to investigate the gene expression of cationic and neutral amino acid (AA) transporters in the small intestine of chick embryos with different genetic backgrounds [Wenshi Yellow-Feathered chick (WYFC) and White Recessive Rock chick (WRRC)]. The study also investigated the correlation between the abundance of AA transporter mRNA and the AA content of fertilized eggs. Intestinal samples were collected on embryonic d 9, 12, 14, 17, and 19 and the day of hatch. The results showed that, before incubation, the AA content of WRRC eggs was lower (P CAT-1 [solute carrier (SLC) family 7 member 1], CAT-4 (SLC family 7 member 4), rBAT (SLC family 3 member 1), y(+)LAT-1 (SLC family 7 member 7), y(+)LAT-2 (SLC family 7 member 6), LAT-4 (SLC family 43 member 2), and SNAT-2 (SLC family 38 member 2), as detected by real-time reverse transcriptase PCR, was greater (P CAT-1, CAT-4, y(+)LAT-2, and LAT-4 in WYFC and on CAT-4 and B(0)AT-1 (SLC family 6 member 19) mRNA expression in WRRC. In WYFC, only CAT-1 mRNA expression was negatively correlated (r = -0.68 to -0.84, P < 0.05) with all AA content. However, few correlations were detected between AA content and the mRNA expression of multiple transporters in WRRC. These findings provide a comprehensive profile of the temporal and spatial mRNA expression of AA transporters in the small intestine of chick embryos. Few correlations were detected between the AA content of the eggs and mRNA expression of specific AA transporters in the small intestine.

  5. JWA,a novel microtubule associate protein,participates cell differentiation signal pathways and also functions as a modulator of amino acid transportation in PC12 cells

    Institute of Scientific and Technical Information of China (English)

    ZhouJW; QunLA

    2002-01-01

    JWA,a novel putative cytoskeleton associated and retinoic acid responsible gene,primarily cloned from ex vivo cultured human tracheal bonchial epithelial cells (1998,GenBank:AF070523).Very little is known of its critical biological function although several homologues of JWA have been identified recently.Our previous data have shown that JWA is widely distributed in human tissues and not only responses to differentiating agents such as all trans retinoic acid (ATRA),13-cis retinoid acid(13-cis RA) and 12-O-tetradecanoyl phorbol-13-acetate(TPA),but actively responsible to environmental stress.In this study,in one hand,we use immuno-fluorescentmicroscopy and immunoprecipitation assay investigated the relationship between JWA and microtubule under treatments of depolymerizing agents (cochicine and nocodizol) and cool-shock.In another hand,we identified and analyzed the promoter sequence of JWA and its structure-based function in regulation of cell differentiation and apoptosis by ATRA,TPA,N-4-hydroxyphenyl-retinamide(4HPR),arsenic trioxide(As2O3) and cytosine arabinoside(Ara C) in NB4 and HL-60) cell lines,and responses to ervironmental stress.In addition,our accumulated evidences showed that JWA might be a stronger moulator which functions amino acids transportation in PC12 cells.It is suggested that JWA might involve in a crosstalk signal pathways in vivo,in vitro and ex vivo systems.Surprisingly,a proposed fusion-size JWA protein was found in both HL-60 cells and fresh APL cells and it might be a novel biomarker for the both.It may give us new insight in understanding the molecular mechanisms in both generation and development of human myeloid leukemia.

  6. Detergent-induced stabilization and improved 3D map of the human heteromeric amino acid transporter 4F2hc-LAT2.

    Directory of Open Access Journals (Sweden)

    Marcel Meury

    Full Text Available Human heteromeric amino acid transporters (HATs are membrane protein complexes that facilitate the transport of specific amino acids across cell membranes. Loss of function or overexpression of these transporters is implicated in several human diseases such as renal aminoacidurias and cancer. HATs are composed of two subunits, a heavy and a light subunit, that are covalently connected by a disulphide bridge. Light subunits catalyse amino acid transport and consist of twelve transmembrane α-helix domains. Heavy subunits are type II membrane N-glycoproteins with a large extracellular domain and are involved in the trafficking of the complex to the plasma membrane. Structural information on HATs is scarce because of the difficulty in heterologous overexpression. Recently, we had a major breakthrough with the overexpression of a recombinant HAT, 4F2hc-LAT2, in the methylotrophic yeast Pichia pastoris. Microgram amounts of purified protein made possible the reconstruction of the first 3D map of a human HAT by negative-stain transmission electron microscopy. Here we report the important stabilization of purified human 4F2hc-LAT2 using a combination of two detergents, i.e., n-dodecyl-β-D-maltopyranoside and lauryl maltose neopentyl glycol, and cholesteryl hemisuccinate. The superior quality and stability of purified 4F2hc-LAT2 allowed the measurement of substrate binding by scintillation proximity assay. In addition, an improved 3D map of this HAT could be obtained. The detergent-induced stabilization of the purified human 4F2hc-LAT2 complex presented here paves the way towards its crystallization and structure determination at high-resolution, and thus the elucidation of the working mechanism of this important protein complex at the molecular level.

  7. Effects of postprandial starvation on mRNA expression of endocrine-, amino acid and peptide transporter-, and metabolic enzyme-related genes in zebrafish (Danio rerio).

    Science.gov (United States)

    Tian, Juan; He, Gen; Mai, Kangsen; Liu, Chengdong

    2015-06-01

    The goal of this study was to systematically evaluate the molecular activities of endocrine-, amino acid and peptide transporters-, and metabolic enzyme-related genes in 35-day-old mixed-sex zebrafish (Danio rerio) after feeding . Zebrafish with initial body weights ranging from 9 to 11 mg were fasted for 384 h in a controlled indoor environment. Fish were sampled at 0, 3, 6, 12, 24, 48, 96, 192, and 384 h after fed. Overall, the present study results show that the regulatory mechanism that insulin-like growth factor I negative feedback regulated growth hormone is conserved in zebrafish, as it is in mammals, but that regulation of growth hormone receptors is highly intricate. Leptin and cholecystokinin are time-dependent negative feedback signals, and neuropeptide Y may be an important positive neuropeptide for food intake in zebrafish. The amino acid/carnitine transporters B(0,+) (ATB(0,+)) and broad neutral (0) amino acid transporter 1(B(0)AT1) mRNA levels measured in our study suggest that protein may be utilized during 24-96 h of fasting in zebrafish. Glutamine synthetase mRNA levels were downregulated, and glutamate dehydrogenase, alanine aminotransferase, aspartate transaminase, and trypsin mRNA levels were upregulated after longtime fasting in this study. The mRNA expression levels of fatty acid synthetase decreased significantly (P < 0.05), whereas those of lipoprotein lipase rapidly increased after 96 h of fasting. Fasting activated the expression of glucose synthesis genes when fasting for short periods of time; when fasting is prolonged, the mRNA levels of glucose breakdown enzymes and pentose phosphate shunt genes decreased. PMID:25805459

  8. Combinatorics of aliphatic amino acids.

    Science.gov (United States)

    Grützmann, Konrad; Böcker, Sebastian; Schuster, Stefan

    2011-01-01

    This study combines biology and mathematics, showing that a relatively simple question from molecular biology can lead to complicated mathematics. The question is how to calculate the number of theoretically possible aliphatic amino acids as a function of the number of carbon atoms in the side chain. The presented calculation is based on earlier results from theoretical chemistry concerning alkyl compounds. Mathematical properties of this number series are highlighted. We discuss which of the theoretically possible structures really occur in living organisms, such as leucine and isoleucine with a chain length of four. This is done both for a strict definition of aliphatic amino acids only involving carbon and hydrogen atoms in their side chain and for a less strict definition allowing sulphur, nitrogen and oxygen atoms. While the main focus is on proteinogenic amino acids, we also give several examples of non-proteinogenic aliphatic amino acids, playing a role, for instance, in signalling. The results are in agreement with a general phenomenon found in biology: Usually, only a small number of molecules are chosen as building blocks to assemble an inconceivable number of different macromolecules as proteins. Thus, natural biological complexity arises from the multifarious combination of building blocks.

  9. 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

  10. Biosynthesis of the Aromatic Amino Acids.

    Science.gov (United States)

    Pittard, James; Yang, Ji

    2008-09-01

    This chapter describes in detail the genes and proteins of Escherichia coli involved in the biosynthesis and transport of the three aromatic amino acids tyrosine, phenylalanine, and tryptophan. It provides a historical perspective on the elaboration of the various reactions of the common pathway converting erythrose-4-phosphate and phosphoenolpyruvate to chorismate and those of the three terminal pathways converting chorismate to phenylalanine, tyrosine, and tryptophan. The regulation of key reactions by feedback inhibition, attenuation, repression, and activation are also discussed. Two regulatory proteins, TrpR (108 amino acids) and TyrR (513 amino acids), play a major role in transcriptional regulation. The TrpR protein functions only as a dimer which, in the presence of tryptophan, represses the expression of trp operon plus four other genes (the TrpR regulon). The TyrR protein, which can function both as a dimer and as a hexamer, regulates the expression of nine genes constituting the TyrR regulon. TyrR can bind each of the three aromatic amino acids and ATP and under their influence can act as a repressor or activator of gene expression. The various domains of this protein involved in binding the aromatic amino acids and ATP, recognizing DNA binding sites, interacting with the alpha subunit of RNA polymerase, and changing from a monomer to a dimer or a hexamer are all described. There is also an analysis of the various strategies which allow TyrR in conjunction with particular amino acids to differentially affect the expression of individual genes of the TyrR regulon. PMID:26443741

  11. Inactivation of the glutamine/amino acid transporter ASCT2 by 1,2,3-dithiazoles: proteoliposomes as a tool to gain insights in the molecular mechanism of action and of antitumor activity

    Energy Technology Data Exchange (ETDEWEB)

    Oppedisano, Francesca [Dipartimento di Biologia Cellulare Università della Calabria, via P. Bucci 4 c, 87036 Arcavacata di Rende (CS) (Italy); Catto, Marco [Dipartimento Farmaco-Chimico, Università degli Studi “Aldo Moro,”, via Orabona 4, 70125 Bari (Italy); Koutentis, Panayiotis A. [Department of Chemistry, University of Cyprus, P.O. Box 20537, 1678 Nicosia (Cyprus); Nicolotti, Orazio [Dipartimento Farmaco-Chimico, Università degli Studi “Aldo Moro,”, via Orabona 4, 70125 Bari (Italy); Pochini, Lorena [Dipartimento di Biologia Cellulare Università della Calabria, via P. Bucci 4 c, 87036 Arcavacata di Rende (CS) (Italy); Koyioni, Maria [Department of Chemistry, University of Cyprus, P.O. Box 20537, 1678 Nicosia (Cyprus); Introcaso, Antonellina [Dipartimento Farmaco-Chimico, Università degli Studi “Aldo Moro,”, via Orabona 4, 70125 Bari (Italy); Michaelidou, Sophia S. [Department of Chemistry, University of Cyprus, P.O. Box 20537, 1678 Nicosia (Cyprus); Carotti, Angelo, E-mail: carotti@farmchim.uniba.it [Dipartimento Farmaco-Chimico, Università degli Studi “Aldo Moro,”, via Orabona 4, 70125 Bari (Italy); Indiveri, Cesare, E-mail: indiveri@unical.it [Dipartimento di Biologia Cellulare Università della Calabria, via P. Bucci 4 c, 87036 Arcavacata di Rende (CS) (Italy)

    2012-11-15

    The ASCT2 transport system catalyses a sodium-dependent antiport of glutamine and other neutral amino acids which is involved in amino acid metabolism. A library of 1,2,3-dithiazoles was designed, synthesized and evaluated as inhibitors of the glutamine/amino acid ASCT2 transporter in the model system of proteoliposomes reconstituted with the rat liver transporter. Fifteen of the tested compounds at concentration of 20 μM or below, inhibited more than 50% the glutamine/glutamine antiport catalysed by the reconstituted transporter. These good inhibitors bear a phenyl ring with electron withdrawing substituents. The inhibition was reversed by 1,4-dithioerythritol indicating that the effect was likely owed to the formation of mixed sulfides with the protein's Cys residue(s). A dose–response analysis of the most active compounds gave IC{sub 50} values in the range of 3–30 μM. Kinetic inhibition studies indicated a non-competitive inhibition, presumably because of a potential covalent interaction of the dithiazoles with cysteine thiol groups that are not located at the substrate binding site. Indeed, computational studies using a homology structural model of ASCT2 transporter, suggested as possible binding targets, Cys-207 or Cys-210, that belong to the CXXC motif of the protein. -- Highlights: ► Non‐competitive inhibition of ASCT2 by 1,2,3-dithiazoles was studied in proteoliposomes. ► Different 1,2,3-dithiazoles were synthesized and evaluated as transporter inhibitors. ► Many compounds potently inhibited the glutamine/glutamine antiport catalyzed by ASCT2. ► The inhibition was reversed by DTE indicating reaction with protein Cys. ► The most active compounds gave IC{sub 50} in the range of 3–30 μM.

  12. Coordinated Regulation of the Neutral Amino Acid Transporter SNAT2 and the Protein Phosphatase Subunit GADD34 Promotes Adaptation to Increased Extracellular Osmolarity*

    Science.gov (United States)

    Krokowski, Dawid; Jobava, Raul; Guan, Bo-Jhih; Farabaugh, Kenneth; Wu, Jing; Majumder, Mithu; Bianchi, Massimiliano G.; Snider, Martin D.; Bussolati, Ovidio; Hatzoglou, Maria

    2015-01-01

    Cells respond to shrinkage induced by increased extracellular osmolarity via programmed changes in gene transcription and mRNA translation. The immediate response to this stress includes the induction of expression of the neutral amino acid transporter SNAT2. Increased SNAT2-mediated uptake of neutral amino acids is an essential adaptive mechanism for restoring cell volume. In contrast, stress-induced phosphorylation of the α subunit of the translation initiation factor eIF2 (eIF2α) can promote apoptosis. Here we show that the response to mild hyperosmotic stress involves regulation of the phosphorylation of eIF2α by increased levels of GADD34, a regulatory subunit of protein phosphatase 1 (PP1). The induction of GADD34 was dependent on transcriptional control by the c-Jun-binding cAMP response element in the GADD34 gene promoter and posttranscriptional stabilization of its mRNA. This mechanism differs from the regulation of GADD34 expression by other stresses that involve activating transcription factor 4 (ATF4). ATF4 was not translated during hyperosmotic stress despite an increase in eIF2α phosphorylation. The SNAT2-mediated increase in amino acid uptake was enhanced by increased GADD34 levels in a manner involving decreased eIF2α phosphorylation. It is proposed that the induction of the SNAT2/GADD34 axis enhances cell survival by promoting the immediate adaptive response to stress. PMID:26041779

  13. Metal induced amino acid adsorption on nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Chia M., E-mail: abinitio@dragon.nchu.edu.t [Research Center for the Remediation of Soil and Ground Water Pollution, Department of Soil and Environmental Sciences, National Chung Hsing University, Taichung 402, Taiwan (China); Jalbout, Abraham F. [Departamento de Investigacion en Fisica, Universidad de Sonora, Hermosillo, Sonora C.P., 83000 Mexico (Mexico)

    2010-02-01

    In this work we detail the mechanism by which alkali metal encapsulation inside an armchair (9,9) single walled carbon nanotube (SWNT) can affect external amino acid interactions. Based on our analysis, several configurations revealed that the physical properties of the SWNT systems are modified by using an internally situated Li atom. Density-functional theory calculations reveal that the most favorable interactions of the SWNT system is with tryptophan, threonine and proline that can be directly correlated to the backbone geometry of the amino acid species.

  14. Development of an Unnatural Amino Acid Incorporation System in the Actinobacterial Natural Product Producer Streptomyces venezuelae ATCC 15439.

    Science.gov (United States)

    He, Jingxuan; Van Treeck, Briana; Nguyen, Han B; Melançon, Charles E

    2016-02-19

    Many Actinobacteria, most notably Streptomyces, produce structurally diverse bioactive natural products, including ribosomally synthesized peptides, by multistep enzymatic pathways. The use of site-specific genetic incorporation of unnatural amino acids to investigate and manipulate the functions of natural product biosynthetic enzymes, enzyme complexes, and ribosomally derived peptides in these organisms would have important implications for drug discovery and development efforts. Here, we have designed, constructed, and optimized unnatural amino acid systems capable of incorporating p-iodo-l-phenylalanine and p-azido-l-phenylalanine site-specifically into proteins in the model natural product producer Streptomyces venezuelae ATCC 15439. We observed notable differences in the fidelity and efficiency of these systems between S. venezuelae and previously used hosts. Our findings serve as a foundation for using an expanded genetic code in Streptomyces to address questions related to natural product biosynthesis and mechanism of action that are relevant to drug discovery and development. PMID:26562751

  15. Economic aspects of amino acids production.

    Science.gov (United States)

    Mueller, Udo; Huebner, Susanna

    2003-01-01

    Amino acids represent basic elements of proteins, which as a main source of nutrition themselves serve as a major reserve for maintaining essential functions of humans as well as animals. Taking the recent state of scientific knowledge into account, the industrial sector of amino acids is a priori "suitable" to a specific kind of an ecologically sound way of production, which is based on biotechnology. The following article may point out characteristics of this particular industrial sector and illustrates the applicability of the latest economic methods, founded on development of the discipline of bionics in order to describe economic aspects of amino acids markets. The several biochemical and technological fields of application of amino acids lead to specific market structures in high developed and permanently evolving systems. The Harvard tradition of industrial economics explains how market structures mould the behaviour of the participants and influences market results beyond that. A global increase in intensity of competition confirms the notion that the supply-side is characterised by asymmetric information in contrast to Kantzenbachs concept of "narrow oligopoly" with symmetrical shared knowledge about market information. Departing from this point, certain strategies of companies in this market form shall be derived. The importance of Research and Development increases rapidly and leads to innovative manufacturing methods which replace more polluting manufacturing processes like acid hydrolysis. In addition to these modifications within the production processes the article deals furthermore with the pricing based on product life cycle concept and introduces specific applications of tools like activity based costing and target costing to the field of amino acid production. The authors come to the conclusion that based on a good transferability of latest findings in bionics and ecological compatibility competitors in amino acids manufacturing are well advised

  16. Economic aspects of amino acids production.

    Science.gov (United States)

    Mueller, Udo; Huebner, Susanna

    2003-01-01

    Amino acids represent basic elements of proteins, which as a main source of nutrition themselves serve as a major reserve for maintaining essential functions of humans as well as animals. Taking the recent state of scientific knowledge into account, the industrial sector of amino acids is a priori "suitable" to a specific kind of an ecologically sound way of production, which is based on biotechnology. The following article may point out characteristics of this particular industrial sector and illustrates the applicability of the latest economic methods, founded on development of the discipline of bionics in order to describe economic aspects of amino acids markets. The several biochemical and technological fields of application of amino acids lead to specific market structures in high developed and permanently evolving systems. The Harvard tradition of industrial economics explains how market structures mould the behaviour of the participants and influences market results beyond that. A global increase in intensity of competition confirms the notion that the supply-side is characterised by asymmetric information in contrast to Kantzenbachs concept of "narrow oligopoly" with symmetrical shared knowledge about market information. Departing from this point, certain strategies of companies in this market form shall be derived. The importance of Research and Development increases rapidly and leads to innovative manufacturing methods which replace more polluting manufacturing processes like acid hydrolysis. In addition to these modifications within the production processes the article deals furthermore with the pricing based on product life cycle concept and introduces specific applications of tools like activity based costing and target costing to the field of amino acid production. The authors come to the conclusion that based on a good transferability of latest findings in bionics and ecological compatibility competitors in amino acids manufacturing are well advised

  17. γ-Amino-butyric acid (GABA) receptor subunit and transporter expression in the gonad and liver of the fathead minnow (Pimephales promelas).

    Science.gov (United States)

    Biggs, Katie; Seidel, Jason S; Wilson, Alex; Martyniuk, Christopher J

    2013-09-01

    γ-Amino-butyric acid (GABA) is the major inhibitory neurotransmitter in the vertebrate central nervous system. GABA receptors and synthesizing enzymes have also been localized to peripheral tissues including the liver, oviduct, uterus and ovary of mammals but the distribution and role of GABA in peripheral tissues of fish has not been fully investigated. The objectives of this study were to (1) determine if mRNA encoding GABA synthesizing enzymes (glutamic acid decarboxylase 65 and 67; gad65 and gad67), GABA transporters, and GABAA receptor subunits are localized to liver and gonad of fathead minnow (Pimephales promelas) (FHM) (2) investigate the effects of GABA on ovarian 17β-estradiol (E2) production, and (3) measure transcript responses in the ovary after in vitro incubation to GABA. Real-time PCR assays were developed for gad65, gad67, vesicular GABA transporter (vgat) and GABA transporter 1 (gat1), and select GABAA receptor subunits (gabra1, gabra5, gabrb1, gabrb2, gabrg1, gabrg2). All transcripts were localized to the brain as expected; however transcripts were also detected in the liver, ovary, and testis of FHMs. In the female liver, gad65 mRNA was significantly higher in expression compared to the male liver. Transcripts for gad67 were the highest in the brain>gonad>liver and in the gonads, gad67 was significantly higher in expression than gad65 mRNA. In the liver and gonad, the relative abundance of the subunits followed a general trend of gabrb1>gabrb2=gabrg1=gabrg2>gabra1=gabra5. To explore the effects of GABA in the ovary, tissue explants from reproductive female FHMs were treated with GABA (10(-10), 10(-8) and 10(-6)M) for 12h. GABA had no significant effect on 17β-estradiol production or on mRNA abundance for genes involved in ovarian steroidogenesis (e.g., 11βhsd, cyp17, cyp19a). There was a significant decrease in estrogen receptor 2a (esr2a) mRNA with 10(-10)M GABA. This study begins to investigate the GABA system in non-neural tissues of

  18. Excitatory amino acid receptor antagonists

    DEFF Research Database (Denmark)

    Johansen, T N; Frydenvang, Karla Andrea; Ebert, B;

    1997-01-01

    We have previously shown that (RS)-2-amino-2-(5-tert-butyl-3-hydroxyisoxazol-4-yl)acetic acid (ATAA) is an antagonist at N-methyl-D-aspartic acid (NMDA) and (RS)-2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propionic acid (AMPA) receptors. We have now resolved ATAA via diastereomeric salt formation......)-phenylethylamine salt of N-BOC-(R)-ATAA. Like ATAA, neither (R)- nor (S)-ATAA significantly affected (IC50 > 100 microM) the receptor binding of tritiated AMPA, kainic acid, or (RS)-3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid, the latter being a competitive NMDA antagonist. Electrophysiological experiments......, using the rat cortical wedge preparation, showed the NMDA antagonist effect as well as the AMPA antagonist effect of ATAA to reside exclusively in the (R)-enantiomer (Ki = 75 +/- 5 microM and 57 +/- 1 microM, respectively). Neither (R)- nor (S)-ATAA significantly reduced kainic acid-induced excitation...

  19. An Impaired Respiratory Electron Chain Triggers Down-regulation of the Energy Metabolism and De-ubiquitination of Solute Carrier Amino Acid Transporters.

    Science.gov (United States)

    Aretz, Ina; Hardt, Christopher; Wittig, Ilka; Meierhofer, David

    2016-05-01

    Hundreds of genes have been associated with respiratory chain disease (RCD), the most common inborn error of metabolism so far. Elimination of the respiratory electron chain by depleting the entire mitochondrial DNA (mtDNA, ρ(0) cells) has therefore one of the most severe impacts on the energy metabolism in eukaryotic cells. In this study, proteomic data sets including the post-translational modifications (PTMs) phosphorylation and ubiquitination were integrated with metabolomic data sets and selected enzyme activities in the osteosarcoma cell line 143B.TK(-) A shotgun based SILAC LC-MS proteomics and a targeted metabolomics approach was applied to elucidate the consequences of the ρ(0) state. Pathway and protein-protein interaction (PPI) network analyses revealed a nonuniform down-regulation of the respiratory electron chain, the tricarboxylic acid (TCA) cycle, and the pyruvate metabolism in ρ(0) cells. Metabolites of the TCA cycle were dysregulated, such as a reduction of citric acid and cis-aconitic acid (six and 2.5-fold), and an increase of lactic acid, oxalacetic acid (both twofold), and succinic acid (fivefold) in ρ(0) cells. Signaling pathways such as GPCR, EGFR, G12/13 alpha, and Rho GTPases were up-regulated in ρ(0) cells, which could be indicative for the mitochondrial retrograde response, a pathway of communication from mitochondria to the nucleus. This was supported by our phosphoproteome data, which revealed two main processes, GTPase-related signal transduction and cytoskeleton organization. Furthermore, a general de-ubiquitination in ρ(0) cells was observed, for example, 80S ribosomal proteins were in average threefold and SLC amino acid transporters fivefold de-ubiquitinated. The latter might cause the observed significant increase of amino acid levels in ρ(0) cells. We conclude that an elimination of the respiratory electron chain, e.g. mtDNA depletion, not only leads to an uneven down-regulation of mitochondrial energy pathways, but also

  20. Cometary Amino Acids from the STARDUST Mission

    Science.gov (United States)

    Cook, Jamie Elsila

    2009-01-01

    NASA's Stardust spacecraft returned samples from comet 81 P/WiId 2 to Earth in January 2006. Examinations of the organic compounds in cometary samples can reveal information about the prebiotic organic inventory present on the early Earth and within the early Solar System, which may have contributed to the origin of life. Preliminary studies of Stardust material revealed the presence of a suite of organic compounds including several amines and amino acids, but the origin of these compounds (cometary vs. terrestrial contamination) could not be identified. We have recently measured the carbon isotopic ratios of these amino acids to determine their origin, leading to the first detection of a cometary amino acid.

  1. Formation of amino acid precursors in the Solar System small bodies using Aluminium-26 as an energy source

    Science.gov (United States)

    Kebukawa, Yoko; Kobayashi, Kensei; Kawai, Jun; Mita, Hajime; Tachibana, Shogo; Yoda, Isao; Misawa, Shusuke

    2016-07-01

    Carbonaceous chondrites contain various organic matter including amino acids that may have played an important role for origin of life on the early Earth. The parent bodies of the chondritic meteorites likely formed from silicate dust grains containing some water ice and organic compounds. These planetesimals are known to contain short-lived radio isotopes such as ^{26}Al, and the heat generated from the decay of ^{26}Al was considered to be used for melting ice. The liquid water, for example, changed anhydrous silicates into hydrous silicates, i.e., aqueous alteration. The liquid water would act also as an ideal reaction medium for various organic chemistry. Cody et al. [1] proposed IOM formation via formose reaction starting with formaldehyde and glycolaldehyde during aqueous activity in the small bodies. Additional hydrothermal experiments showed that ammonia enhanced the yields of IOM like organic solids [2]. Formaldehyde and ammonia are ubiquitous in the Solar System and beyond, e.g., comets contain H _{2}CO : NH _{3} : H _{2}O = 0.4-4 : 0.5-1.5 : 100 [3]. Thus these molecules can be expected to have existed in some Solar System small bodies. We study the liquid phase chemistry of the formaldehyde and ammonia, including formations of amino acid precursor molecules, via hydrothermal experiments at isothermal temperatures of 90 °C to 200 °C. We also evaluate the effects of gamma-ray which is released from the decay of ^{26}Al with gamma-ray irradiation experiments using a ^{60}Co gamma-ray source at Tokyo Institute of Technology. Amino acids were detected mostly after acid hydrolysis of heated or irradiated solutions, indicating that most of the amino acids in the products exist as precursors. Some samples contained 'free' amino acids that were detected without acid hydrolysis, but much lower abundance than after acid hydrolysis. Kendrick mass defect (KMD) analyses of High resolution mass spectra obtained using ESI-MS revealed that various CHO and CHNO

  2. Amino acid efflux in the isolated perfused rat pancreas: trans-stimulation by extracellular amino acids.

    Science.gov (United States)

    Mann, G E; Norman, P S; Smith, I C

    1989-01-01

    1. Epithelial uptake and efflux of the non-metabolized system A analogue 2-methylaminoisobutyric acid (MeAIB) and L-serine were studied in the isolated perfused rat pancreas using a dual tracer loading and wash-out technique. Uptakes of 2-[14C]MeAIB and L-[3H]serine were measured relative to D-[3H or 14C]mannitol (extracellular tracer) during a 20 min cell loading period. Maximal uptake for MeAIB (34 +/- 2%, n = 6) occurred within 2-3 min and decreased to 14 +/- 2% after 20 min tracer loading. Uptake for L-serine reached a maximum (62 +/- 4%, n = 7) within 1 min and decreased to 19 +/- 2% after 20 min tracer loading. 2. When tracer wash-out was monitored during subsequent perfusion of the preloaded pancreas with an isotope-free solution, D-mannitol predominantly cleared from a fast exchanging compartment (0.54 +/- 0.05 ml g-1, n = 9) with a time constant (Tfast) of 0.68 +/- 0.04 min. Although MeAIB and L-serine exhibited similar fast phases of wash-out, a much larger efflux occurred from a slowly exchanging pool with respective time constants (Tslow) of 15.47 +/- 0.45 min (n = 6) and 5.98 +/- 0.46 min (n = 7). 3. A rapid vascular challenge of the pancreas with 100 mM-L-serine transiently accelerated cellular efflux of 2-[14C]MeAIB and L-[3H]serine without affecting wash-out of D-[14C]mannitol. Tracer efflux following cell loading with 2-[14C]MeAIB or L-[3H]serine was not stimulated by a challenge with 100 mM-MeAIB. 4. The time course of amino acid evoked 2-[14C]MeAIB and L-[3H]serine efflux paralleled the extracellular dilution profile of a vascular stimulus, suggesting that the acceleration of efflux was due to trans-stimulation. 5. Trans-stimulation of 2-[14C]MeAIB and L-[3H]serine efflux by a further twenty-two naturally occurring and three synthetic amino acids was then examined. L-Proline, N-methyl-DL-alanine, L-lysine and D-lysine selectively stimulated MeAIB efflux. Efflux of both tracer amino acids was accelerated by aminoisobutyric acid (AIB), L-serine, L

  3. Influence of Free Amino Acids, Oligopeptides, and Polypeptides on the Formation of Pyrazines in Maillard Model Systems.

    Science.gov (United States)

    Scalone, Gustavo Luis Leonardo; Cucu, Tatiana; De Kimpe, Norbert; De Meulenaer, Bruno

    2015-06-10

    Pyrazines are specific Maillard reaction compounds known to contribute to the unique aroma of many products. Most studies concerning the generation of pyrazines in the Maillard reaction have focused on amino acids, while little information is available on the impact of peptides and proteins. The present study investigated the generation of pyrazines in model systems containing whey protein, hydrolyzed whey protein, amino acids, and glucose. The impact of thermal conditions, ratio of reagents, and water activity (a(w)) on pyrazine formation was measured by headspace solid-phase microextraction with gas chromatography/mass spectrometry (HS-SPME-GC/MS. The presence of oligopeptides from hydrolyzed whey protein contributed significantly to an increased amount of pyrazines, while in contrast free amino acids generated during protein hydrolysis contributed to a lesser extent. The generation of pyrazines was enhanced at low a(w) (0.33) and high temperatures (>120 °C). This study showed that the role of peptides in the generation of pyrazines in Maillard reaction systems has been dramatically underestimated. PMID:25971942

  4. Association with Amino Acids Does Not Enhance Efficacy of Polymerized Liposomes As a System for Lung Gene Delivery.

    Science.gov (United States)

    Bandeira, Elga; Lopes-Pacheco, Miquéias; Chiaramoni, Nadia; Ferreira, Débora; Fernandez-Ruocco, Maria J; Prieto, Maria J; Maron-Gutierrez, Tatiana; Perrotta, Ramiro M; de Castro-Faria-Neto, Hugo C; Rocco, Patricia R M; Alonso, Silvia Del Valle; Morales, Marcelo M

    2016-01-01

    Development of improved drug and gene delivery systems directly into the lungs is highly desirable given the important burden of respiratory diseases. We aimed to evaluate the safety and efficacy of liposomes composed of photopolymerized lipids [1,2-bis-(tricosa-10,12-diynoyl)-sn-glycero-3-phosphocholine] associated with amino acids as vectors for gene delivery into the lungs of healthy animals. Lipopolymer vesicles, in particular, are more stable than other types of liposomes. In this study, lipopolymers were associated with l-arginine, l-tryptophan, or l-cysteine. We hypothesized that the addition of these amino acids would enhance the efficacy of gene delivery to the lungs by the lipopolymers. l-Arginine showed the highest association efficiency due to its positive charge and better surface interactions. None of the formulations caused inflammation or altered lung mechanics, suggesting that these lipopolymers can be safely administered as aerosols. All formulations were able to induce eGFP mRNA expression in lung tissue, but the addition of amino acids reduced delivery efficacy when compared with the simple lipopolymer particle. These results indicate that this system could be further explored for gene or drug delivery targeting lung diseases. PMID:27199766

  5. Association with amino acids does not enhance efficacy of polymerized liposomes as a system for lung gene delivery

    Directory of Open Access Journals (Sweden)

    Elga eBernardo Bandeira De Melo

    2016-04-01

    Full Text Available Development of improved drug and gene delivery systems directly into the lungs is highly desirable given the important burden of respiratory diseases. We aimed to evaluate the safety and efficacy of liposomes composed of photopolymerized lipids (1,2-bis-(tricosa-10,12-diynoyl-sn-glycero-3-phosphocholine associated with amino acids as vectors for gene delivery into the lungs of healthy animals. Lipopolymer vesicles, in particular, are more stable than other types of liposomes. In this study, lipopolymers were associated with L-arginine, L-tryptophan, or L-cysteine. We hypothesized that the addition of these amino acids would enhance the efficacy of gene delivery to the lungs by the lipopolymers. L-Arginine showed the highest association efficiency due to its positive charge and better surface interactions. None of the formulations caused inflammation or altered lung mechanics, suggesting that these lipopolymers can be safely administered as aerosols. All formulations were able to induce eGFP mRNA expression in lung tissue, but the addition of amino acids reduced delivery efficacy when compared with the simple lipopolymer particle. These results indicate that this system could be further explored for gene or drug delivery targeting lung diseases.

  6. Association with Amino Acids Does Not Enhance Efficacy of Polymerized Liposomes As a System for Lung Gene Delivery

    Science.gov (United States)

    Bandeira, Elga; Lopes-Pacheco, Miquéias; Chiaramoni, Nadia; Ferreira, Débora; Fernandez-Ruocco, Maria J.; Prieto, Maria J.; Maron-Gutierrez, Tatiana; Perrotta, Ramiro M.; de Castro-Faria-Neto, Hugo C.; Rocco, Patricia R. M.; Alonso, Silvia del Valle; Morales, Marcelo M.

    2016-01-01

    Development of improved drug and gene delivery systems directly into the lungs is highly desirable given the important burden of respiratory diseases. We aimed to evaluate the safety and efficacy of liposomes composed of photopolymerized lipids [1,2-bis-(tricosa-10,12-diynoyl)-sn-glycero-3-phosphocholine] associated with amino acids as vectors for gene delivery into the lungs of healthy animals. Lipopolymer vesicles, in particular, are more stable than other types of liposomes. In this study, lipopolymers were associated with l-arginine, l-tryptophan, or l-cysteine. We hypothesized that the addition of these amino acids would enhance the efficacy of gene delivery to the lungs by the lipopolymers. l-Arginine showed the highest association efficiency due to its positive charge and better surface interactions. None of the formulations caused inflammation or altered lung mechanics, suggesting that these lipopolymers can be safely administered as aerosols. All formulations were able to induce eGFP mRNA expression in lung tissue, but the addition of amino acids reduced delivery efficacy when compared with the simple lipopolymer particle. These results indicate that this system could be further explored for gene or drug delivery targeting lung diseases. PMID:27199766

  7. Feasibility of labeled α-acetamido-aminoisobutyric acid as new tracer compound for kinetic labeling of neutral amino acid transport: Preparation of α-(N-[1-11C]acetyl)- and α-(N-[1-14C]acetyl)-aminoisobutyric acid

    International Nuclear Information System (INIS)

    The nonphysiological, nonracemic, branched-chain α-acetamido-aminoisobutyric acid was labeled with the carbon isotope 11C with the intention to use it in conjunction with positron emission tomography (PET) to measure the kinetics of amino acid transport in vivo. It was produced by the reaction of the novel 11C-precursor N-[1-11C]acetylpyridinium chloride with α-aminoisobutyric acid. Typically, 2 GBq of α-(N-[1-11C]acetyl)-aminoisobutyric acid were isolated with a specific activity of 12 to 20 GBq · μmol-1 at the time of application, and with a radiochemical purity of >98%. The chemical identity of α-(N-[1-11C]acetyl)-aminoisobutyric acid was confirmed by comparison with α-(N-[1-14C]acetyl)-aminoisobutyric acid that was independently prepared by a standard acetylation procedure of α-aminoisobutyric acid using [1-14C]acetic anhydride. In vivo, both labeled substrates were not metabolized. In cell-culture experiments, 84% of the substrate entered the cells by the sodium-dependent amino acid transport system A, whereas 16% was taken up by the sodium-independent system. The uptake of the radiotracer was measured 20 min and 40 min postinjection in tumor-bearing male Copenhagen rats for assessment of its in vivo biodistribution

  8. Seasonal variations in the amino acid profile and protein nutritional value of Saccharina latissima cultivated in a commercial IMTA system

    DEFF Research Database (Denmark)

    Silva Marinho, Goncalo; Holdt, Susan Løvstad; Angelidaki, Irini

    2015-01-01

    . Aspartic and glutamic acids dominated the amino acid profile, accounting for up to 49 % of the total. Greatest seasonal differences in amino acid composition occurred in July, with leucine contributing most (22.7–26.7 %) of the observed differences. A maximal essential amino acid (EAA) score of 68.......9 % (based on WHO/FAO/UNU requirements) was achieved in November 2013. The presence of epiphytes in July to November changed neither the amino acid content nor the EAA score. S. latissima is comparable with wheat as a protein ingredient for fish feed and appears to be a suitable protein/amino acid source...... for human consumption. This study proposes that there may be a mismatch between harvest time and nutritional value. The preferable harvest time for S. latissima is November, due to high protein content and EAA score. However, higher yield and cleaner biomass for human consumption would be found in May....

  9. Amino acid analyses of Apollo 14 samples.

    Science.gov (United States)

    Gehrke, C. W.; Zumwalt, R. W.; Kuo, K.; Aue, W. A.; Stalling, D. L.; Kvenvolden, K. A.; Ponnamperuma, C.

    1972-01-01

    Detection limits were between 300 pg and 1 ng for different amino acids, in an analysis by gas-liquid chromatography of water extracts from Apollo 14 lunar fines in which amino acids were converted to their N-trifluoro-acetyl-n-butyl esters. Initial analyses of water and HCl extracts of sample 14240 and 14298 samples showed no amino acids above background levels.

  10. Unnatural reactive amino acid genetic code additions

    Science.gov (United States)

    Deiters, Alexander; Cropp, T. Ashton; Chin, Jason W.; Anderson, J. Christopher; Schultz, Peter G.

    2014-08-26

    This invention provides compositions and methods for producing translational components that expand the number of genetically encoded amino acids in eukaryotic cells. The components include orthogonal tRNAs, orthogonal aminoacyl-tRNA synthetases, orthogonal pairs of tRNAs/synthetases and unnatural amino acids. Proteins and methods of producing proteins with unnatural amino acids in eukaryotic cells are also provided.

  11. Unnatural reactive amino acid genetic code additions

    Energy Technology Data Exchange (ETDEWEB)

    Deiters, Alexander; Cropp, Ashton T; Chin, Jason W; Anderson, Christopher J; Schultz, Peter G

    2013-05-21

    This invention provides compositions and methods for producing translational components that expand the number of genetically encoded amino acids in eukaryotic cells. The components include orthogonal tRNAs, orthogonal aminoacyl-tRNA synthetases, pairs of tRNAs/synthetases and unnatural amino acids. Proteins and methods of producing proteins with unnatural amino acids in eukaryotic cells are also provided.

  12. Amino acids as antioxidants for frying oil

    Science.gov (United States)

    Amino acids, proteins and hydrolysates of proteins have been known to protect edible oils from oxidation. While amino acids and related materials have high potential as antioxidants for frying oil, effectiveness of each amino acid and mechanisms of their activities are not well understood yet. Propo...

  13. Separation of clavulanic acid from fermented broth of amino acids by an aqueous two-phase system and ion-exchange adsorption.

    Science.gov (United States)

    da Silva, Clovis Sacardo; Cuel, Maressa Fabiano; Barreto, Verônica Orlandin; Kwong, Wu Hong; Hokka, Carlos O; Barboza, M

    2012-02-15

    The clavulanic acid is a substance which inhibits the β-lactamases used with penicillins for therapeutic treatment. After the fermentation, by-products of low molecular weight such as amino acids lysine, histidine, proline and tyrosine are present in the fermented broth. To remove these impurities the techniques of extraction by an aqueous two-phase system of 17% polyethylene glycol molecular weight 600 and 15% potassium phosphate were used for a partial purification. A subsequent ion-exchange adsorption was used for the recuperation of the clavulanic acid of the top phase and purification getting a concentration factor of 2 and purification of 100% in relation to the amino acids lysine, histidine, proline and tyrosine.

  14. Pharmacological characterization of human excitatory amino acid transporters EAAT1, EAAT2 and EAAT3 in a fluorescence-based membrane potential assay

    DEFF Research Database (Denmark)

    Jensen, Anders A.; Bräuner-Osborne, Hans

    2004-01-01

    (FMP) assay. The K(m) and K(i) values obtained for 12 standard EAAT ligands at EAAT1, EAAT2 and EAAT3 in the FMP assay correlated well with the K(i) values obtained in the [(3) H]-d-aspartate assay (r(2) values of 0.92, 0.92, and 0.95, respectively). Furthermore, the pharmacological characteristics......We have expressed the human excitatory amino acid transporters EAAT1, EAAT2 and EAAT3 stably in HEK293 cells and characterized the transporters pharmacologically in a conventional [(3) H]-d-aspartate uptake assay and in a fluorescence-based membrane potential assay, the FLIPR Membrane Potential...... conventional electrophysiology set-ups might be superior in terms of studying sophisticated kinetic aspects of the uptake process, the FMP assay enables the collection of considerable amounts of highly reproducible data with relatively little labor. Furthermore, considering that the number of EAAT ligands...

  15. The Role of Microbial Amino Acid Metabolism in Host Metabolism

    Directory of Open Access Journals (Sweden)

    Evelien P. J. G. Neis

    2015-04-01

    Full Text Available Disruptions in gut microbiota composition and function are increasingly implicated in the pathogenesis of obesity, insulin resistance, and type 2 diabetes mellitus. The functional output of the gut microbiota, including short-chain fatty acids and amino acids, are thought to be important modulators underlying the development of these disorders. Gut bacteria can alter the bioavailability of amino acids by utilization of several amino acids originating from both alimentary and endogenous proteins. In turn, gut bacteria also provide amino acids to the host. This could have significant implications in the context of insulin resistance and type 2 diabetes mellitus, conditions associated with elevated systemic concentrations of certain amino acids, in particular the aromatic and branched-chain amino acids. Moreover, several amino acids released by gut bacteria can serve as precursors for the synthesis of short-chain fatty acids, which also play a role in the development of obesity. In this review, we aim to compile the available evidence on the contribution of microbial amino acids to host amino acid homeostasis, and to assess the role of the gut microbiota as a determinant of amino acid and short-chain fatty acid perturbations in human obesity and type 2 diabetes mellitus.

  16. Metabolism and transport of gamma-carboxyglutamic acid.

    Science.gov (United States)

    Shah, D V; Tews, J K; Harper, A E; Suttie, J W

    1978-03-01

    gamma-Carboxyglutamic acid residues have beeh shown to be present in prothrombin, the other vitamin K-dependent clotting factors, and more recently in bone and kidney proteins. This amino acid is formed by a posttranslational vitamin K-dependent carboxylation of glutamyl residues in polypeptide precursors of these protens. It has now been demonstrated that this amino acid, either in the free or peptide-bound form, is not metabolically degraded by the rat, but is quantitatively excreted in the urine. In nephrectomized rats, the tissue concentration of intravenously administered gamma-carboxyglutamic acid is increased, but there is still no evidence of any oxidative metabolism of this amino acid. These amino acid is transported by kidney slices against a concentration gradient, but does not accumulate in liver, intestinal or brain tissues. Preliminary data suggest that gamma-carboxyglutamic acid may be concentrated by a carrier system different from that utilized by other amino acids. PMID:629998

  17. Importin α3/Qip1 is involved in multiplication of mutant influenza virus with alanine mutation at amino acid 9 independently of nuclear transport function.

    Directory of Open Access Journals (Sweden)

    Yutaka Sasaki

    Full Text Available The nucleoprotein (NP of influenza A virus is transported into the nucleus via the classical importin α/β pathway, and proceeds via nuclear localization signals (NLSs recognized by importin α molecules. Although NP binds to importin α isoforms Rch1, Qip1 and NPI-1, the role of each individual isoform during the nuclear transport of NP and replication of the influenza virus remains unknown. In this study, we examined the contribution of importin α isoforms for nuclear localization of NP and viral growth using a panel of NP mutants containing serial alanine replacements within an unconventional NLS of NP. Alanine mutation at amino acid 8 (R8A caused a significant reduction in the nuclear localization and binding to the three importin isoforms. The R8A NP mutant virus did not generate by reverse-genetics approach. This indicates that position 8 is the main site that mediates nuclear localization via interactions with Rch1, Qip1 and NPI-1, and subsequent viral production. This was confirmed by the finding that the conservation of amino acid 8 in human- and avian-origin influenza virus NP was necessary for virus propagation. By contrast, another mutant, S9A NP, which localized in the nucleus, caused a reduction in viral growth and vRNA transcription, suggesting that the unconventional NLS within NP may be associated with nuclear transport, vRNA transcription and viral replication through independent pathways. Interestingly, the N-terminal 110-amino acid region, which contained the unconventional NLS with S9A mutation, mainly bound to Qip1. Furthermore, activities of vRNA transcription and replication of S9A NP mutants were decreased by silencing Qip1 in without changing nuclear localization, indicating that Qip1 involves in multiplication of S9A mutant virus independently of nuclear transport function. Collectively, our results demonstrate the unconventional NLS within NP might have the additional ability to regulate the viral replication that

  18. Current topics in the biotechnological production of essential amino acids, functional amino acids, and dipeptides.

    Science.gov (United States)

    Mitsuhashi, Satoshi

    2014-04-01

    Amino acids play important roles in both human and animal nutrition and in the maintenance of health. Here, amino acids are classified into three groups: first, essential amino acids, which are essential to nutrition; second, functional amino acids, recently found to be important in the promotion of physiological functions; and third, dipeptides, which are used to resolve problematic features of specific free amino acids, such as their instability or insolubility. This review focusses on recent researches concerning the microbial production of essential amino acids (lysine and methionine), functional amino acids (histidine and ornithine), and a dipeptide (L-alanyl-L-glutamine). PMID:24679256

  19. Data set for cloning and characterization of heterologous transporters in Saccharomyces cerevisiae and identification of important amino acids for xylose utilization

    Directory of Open Access Journals (Sweden)

    Chengqiang Wang

    2015-09-01

    Full Text Available The efficient uptake is important for the xylose utilization by Saccharomyces cerevisiae. A heterogenous transporter Mgt05196p was cloned from Meyerozyma guilliermondii and expressed in Saccharomyces cerevisiae [1]. This data article contains the transport characteristics of Mgt05196p in S. cerevisiae. The fluorescence of fusion protein Mgt05196p-GFP expressing strain was located on the cell surface demonstrated that the heterogenous transporter Mgt05196p was targeted to the plasma membrane of S. cerevisiae. The expressing of Mgt05196p in the hxt null S. cerevisiae endowed the strain with the glucose and d-xylose absorption capacity, as well as expressing the native d-xylose transporter Gal2p. The transmembrane domains of Mgt05196p were predicted and compared with the XylEp, whose crystal structure was revealed. And then, the homologous modeling of Mgt05196p was built basing on the XylEp to find out the crucial amino acid residues for sugars binding and transport.

  20. Structural basis for the hydrolysis of ATP by a nucleotide binding subunit of an amino acid ABC transporter from Thermus thermophilus.

    Science.gov (United States)

    Devi, Seenivasan Karthiga; Chichili, Vishnu Priyanka Reddy; Jeyakanthan, J; Velmurugan, D; Sivaraman, J

    2015-06-01

    ATP-binding cassette (ABC) transporters are a major family of small molecule transporter proteins, and their deregulation is associated with several diseases, including cancer. Here, we report the crystal structure of the nucleotide binding domain (NBD) of an amino acid ABC transporter from Thermus thermophilus (TTHA1159) in its apo form and as a complex with ADP along with functional studies. TTHA1159 is a putative arginine ABC transporter. The apo-TTHA1159 was crystallized in dimeric form, a hitherto unreported form of an apo NBD. Structural comparison of the apo and ADP-Mg(2+) complexes revealed that Phe14 of TTHA1159 undergoes a significant conformational change to accommodate ADP, and that the bound ADP interacts with the P-loop (Gly40-Thr45). Modeling of ATP-Mg(2+):TTHA1159 complex revealed that Gln86 and Glu164 are involved in water-mediated hydrogen bonding contacts and Asp163 in Mg(2+) ion-mediated hydrogen bonding contacts with the γ-phosphate of ATP, consistent with the findings of other ABC transporters. Mutational studies confirmed the necessity of each of these residues, and a comparison of the apo/ADP Mg(2+):TTHA1159 with its ATP-complex model suggests the likelihood of a key conformational change to the Gln86 side chain for ATP hydrolysis. PMID:25916755

  1. Uptake of Branched-Chain Amino Acids by Streptococcus thermophilus

    OpenAIRE

    Akpemado, K. M.; Bracquart, P. A.

    1983-01-01

    The transport of branched-chain amino acids in Streptococcus thermophilus was energy dependent. The metabolic inhibitors of glycolysis and ATPase enzymes were active, but the proton-conducting uncouplers were not. Transport was optimal at temperatures of between 30 and 45°C and at pH 7.0 for the three amino acids leucine, valine, and isoleucine; a second peak existed at pH 5.0 with valine and isoleucine. By competition and kinetics studies, the branched-chain amino acids were found to share a...

  2. Non-physiological amino acid (NPAA) therapy targeting brain phenylalanine reduction: pilot studies in PAHENU2 mice.

    Science.gov (United States)

    Vogel, Kara R; Arning, Erland; Wasek, Brandi L; Bottiglieri, Teodoro; Gibson, K Michael

    2013-05-01

    Transport of large neutral amino acids (LNAA) across the blood brain barrier (BBB) is facilitated by the L-type amino acid transporter, LAT1. Peripheral accumulation of one LNAA (e.g., phenylalanine (phe) in PKU) is predicted to increase uptake of the offending amino acid to the detriment of others, resulting in disruption of brain amino acid homeostasis. We hypothesized that selected non-physiological amino acids (NPAAs) such as DL-norleucine (NL), 2-aminonorbornane (NB; 2-aminobicyclo-(2,1,1)-heptane-2-carboxylic acid), 2-aminoisobutyrate (AIB), and N-methyl-aminoisobutyrate (MAIB), acting as competitive inhibitors of various brain amino acid transporters, could reduce brain phe in Pah (enu2) mice, a relevant murine model of PKU. Oral feeding of 5 % NL, 5 % AIB, 0.5 % NB and 3 % MAIB reduced brain phe by 56 % (p amino acids) were also observed, however, with MAIB displaying the mildest effects. Of interest, MAIB represents an inhibitor of the system A (alanine) transporter that primarily traffics small amino acids and not LNAAs. Our studies represent the first in vivo use of these NPAAs in Pah (enu2) mice, and provide proof-of-principle for their further preclinical development, with the long-term objective of identifying NPAA combinations and concentrations that selectively restrict brain phe transport while minimally impacting other LNAAs and downstream intermediates.

  3. Amino acid properties conserved in molecular evolution.

    Directory of Open Access Journals (Sweden)

    Witold R Rudnicki

    Full Text Available That amino acid properties are responsible for the way protein molecules evolve is natural and is also reasonably well supported both by the structure of the genetic code and, to a large extent, by the experimental measures of the amino acid similarity. Nevertheless, there remains a significant gap between observed similarity matrices and their reconstructions from amino acid properties. Therefore, we introduce a simple theoretical model of amino acid similarity matrices, which allows splitting the matrix into two parts - one that depends only on mutabilities of amino acids and another that depends on pairwise similarities between them. Then the new synthetic amino acid properties are derived from the pairwise similarities and used to reconstruct similarity matrices covering a wide range of information entropies. Our model allows us to explain up to 94% of the variability in the BLOSUM family of the amino acids similarity matrices in terms of amino acid properties. The new properties derived from amino acid similarity matrices correlate highly with properties known to be important for molecular evolution such as hydrophobicity, size, shape and charge of amino acids. This result closes the gap in our understanding of the influence of amino acids on evolution at the molecular level. The methods were applied to the single family of similarity matrices used often in general sequence homology searches, but it is general and can be used also for more specific matrices. The new synthetic properties can be used in analyzes of protein sequences in various biological applications.

  4. A putative amino acid ABC transporter substrate-binding protein, NMB1612, from Neisseria meningitidis, induces murine bactericidal antibodies against meningococci expressing heterologous NMB1612 proteins.

    Science.gov (United States)

    Hung, Miao-Chiu; Humbert, María Victoria; Laver, Jay R; Phillips, Renee; Heckels, John E; Christodoulides, Myron

    2015-08-26

    The nmb1612 (NEIS1533) gene encoding the ~27-kDa putative amino acid ATP-binding cassette (ABC) transporter, periplasmic substrate-binding protein from Neisseria meningitidis serogroup B (MenB) strain MC58 was cloned and expressed in Escherichia coli, and the purified recombinant (r)NMB1612 was used for animal immunization studies. Immunization of mice with rNMB1612 adsorbed to Al(OH)3 and in liposomes with and without MPLA, induced antiserum with bactericidal activity in an assay using baby rabbit complement, against the homologous strain MC58 (encoding protein representative of Allele 62) and killed heterologous strains encoding proteins of three other alleles (representative of Alleles 1, 64 and 68), with similar SBA titres. However, strain MC58 was not killed (titre protein was killed (median titres of 16-64 in the hSBA). Analysis of the NMB1612 amino acid sequences from 4351 meningococcal strains in the pubmlst.org/Neisseria database and a collection of 13 isolates from colonized individuals and from patients, showed that antibodies raised against rNMB1612 could potentially kill at least 72% of the MenB strains in the complete sequence database. For MenB disease occurring specifically in the UK from 2013 to 2015, >91% of the isolates causing disease in this recent period expressed NMB1612 protein encoded by Allele 1 and could be potentially killed by sera raised to the recombinant antigen in the current study. The NMB1612 protein was surface-accessible and expressed by different meningococcal strains. In summary, the properties of (i) NMB1612 protein conservation and expression, (ii) limited amino acid sequence variation between proteins encoded by different alleles, and (iii) the ability of a recombinant protein to induce cross-strain bactericidal antibodies, would all suggest a promising antigen for consideration for inclusion in new meningococcal vaccines.

  5. Pairwise amino acid secondary structural propensities

    Science.gov (United States)

    Chemmama, Ilan E.; Chapagain, Prem P.; Gerstman, Bernard S.

    2015-04-01

    We investigate the propensities for amino acids to form a specific secondary structure when they are paired with other amino acids. Our investigations use molecular dynamics (MD) computer simulations, and we compare the results to those from the Protein Data Bank (PDB). Proper comparison requires weighting of the MD results in a manner consistent with the relative frequency of appearance in the PDB of each possible pair of amino acids. We find that the propensity for an amino acid to assume a secondary structure varies dramatically depending on the amino acid that is before or after it in the primary sequence. This cooperative effect means that when selecting amino acids to facilitate the formation of a secondary structure in peptide engineering experiments, the adjacent amino acids must be considered. We also examine the preference for a secondary structure in bacterial proteins and compare the results to those of human proteins.

  6. Amino acids in the cultivation of mammalian cells.

    Science.gov (United States)

    Salazar, Andrew; Keusgen, Michael; von Hagen, Jörg

    2016-05-01

    Amino acids are crucial for the cultivation of mammalian cells. This importance of amino acids was realized soon after the development of the first cell lines, and a solution of a mixture of amino acids has been supplied to cultured cells ever since. The importance of amino acids is further pronounced in chemically defined mammalian cell culture media, making the consideration of their biological and chemical properties necessary. Amino acids concentrations have been traditionally adjusted to their cellular consumption rates. However, since changes in the metabolic equilibrium of amino acids can be caused by changes in extracellular concentrations, metabolomics in conjunction with flux balance analysis is being used in the development of culture media. The study of amino acid transporters is also gaining importance since they control the intracellular concentrations of these molecules and are influenced by conditions in cell culture media. A better understanding of the solubility, stability, dissolution kinetics, and interactions of these molecules is needed for an exploitation of these properties in the development of dry powdered chemically defined media for mammalian cells. Due to the complexity of these mixtures however, this has proven to be challenging. Studying amino acids in mammalian cell culture media will help provide a better understanding of how mammalian cells in culture interact with their environment. It would also provide insight into the chemical behavior of these molecules in solutions of complex mixtures, which is important in the understanding of the contribution of individual amino acids to protein structure.

  7. Molecular interactions of α-amino acids insight into aqueous β-cyclodextrin systems.

    Science.gov (United States)

    Ekka, Deepak; Roy, Mahendra Nath

    2013-10-01

    Qualitative and quantitative analysis of molecular interaction prevailing in glycine, L-alanine, L-valine and aqueous solution of β-cyclodextrin (β-CD) have been probed by thermophysical properties. Density (ρ), viscosity (η), and ultrasonic speed (u) measurements have been reported at different temperatures. The extent of interaction (solute-solvent interaction) is expressed in terms of the limiting apparent molar volume ([Formula: see text]), viscosity B-coefficient and limiting apparent molar adiabatic compressibility ([Formula: see text]). The changes on the enthalpy ([Formula: see text]) and entropy ([Formula: see text]) of the encapsulation analysis give information about the driving forces governing the inclusion. The temperature dependence behaviour of partial molar quantities and group contributions to partial molar volumes has been determined for the amino acids. The trends in transfer volumes, [Formula: see text], have been interpreted in terms of solute-cosolute interactions based on a cosphere overlap model. The role of the solvent (aqueous solution of β-CD) and the contribution of solute-solute and solute-solvent interactions to the solution complexes have also been analyzed through the derived properties.

  8. α-Amino Acid-Isosteric α-Amino Tetrazoles

    NARCIS (Netherlands)

    Zhao, Ting; Kurpiewska, Katarzyna; Kalinowska-Tłuścik, Justyna; Herdtweck, Eberhardt; Dömling, Alexander

    2016-01-01

    The synthesis of all 20 common natural proteinogenic and 4 otherα-amino acid-isosteric α-amino tetrazoles has been accomplished, whereby the carboxyl group is replaced by the isosteric 5-tetrazolyl group. The short process involves the use of the key Ugi tetrazole reaction followed by deprotection c

  9. Reconstructing Amino Acid Interaction Networks by an Ant Colony Approach

    OpenAIRE

    Gaci, Omar; Balev, Stefan

    2009-01-01

    In this paper we introduce the notion of protein interaction network. This is a graph whose vertices are the proteins amino acids and whose edges are the interactions between them. We consider the problem of reconstructing protein's interaction network from its amino acid sequence. We rely on a probability that two amino acids interact as a function of their physico-chemical properties coupled to an ant colony system to solve this problem.

  10. A Novel Synthesis of β-Hydroxy-α-amino Acids

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhi-Hui; LI Shuo; XU Pen-gFei

    2003-01-01

    @@ β-hydroxy-α-amino acids constitute an important class of compounds as naturally occurring amino acids and as components of many complex natural products possessing a wide range of biological activities. [1] As a consequence of the essential role played by these amino acids in the biological systems and their utility as synthetic building blocks, a number of useful strategies have been devised for their preparation. [2

  11. High- and low-affinity binding of S-citalopram to the human serotonin transporter mutated at 20 putatively important amino acid positions

    DEFF Research Database (Denmark)

    Plenge, Per; Wiborg, Ove

    2005-01-01

    The serotonin transporter (SERT) is responsible for terminating or modulating the action of serotonin released from the presynaptic neuron and is the major target for most antidepressants including the tricyclic antidepressants and the selective serotonin uptake inhibitors. Two binding sites...... for uptake inhibitors and serotonin (5-HT) have been found on SERT. At one site, uptake inhibitors bind with high-affinity to SERT, thereby blocking the uptake of 5-HT. The other site is a low-affinity allosteric site, which influences the dissociation of uptake inhibitors, such as imipramine, paroxetine......, and citalopram from the first site, when occupied by 5-HT and a few uptake inhibitors like paroxetine and citalopram. In this study, the connection between the high-affinity binding site and the allosteric affinity-modulating site was investigated by introducing 20 single amino acid substitutions into positions...

  12. The mouse and human excitatory amino acid transporter gene (EAAT1) maps to mouse chromosome 15 and a region of syntenic homology on human chromosome 5

    Energy Technology Data Exchange (ETDEWEB)

    Kirschner, M.A.; Arriza, J.L.; Amara, S.G. [Oregon Health Sciences Univ., Portland, OR (United States)] [and others

    1994-08-01

    The gene for human excitatory amino acid transporter (EAAT1) was localized to the distal region of human chromosome 5p13 by in situ hybridization of metaphase chromosome spreads. Interspecific backcross analysis identified the mouse Eaat1 locus in a region of 5p13 homology on mouse chromosome 15. Markers that are linked with EAAT1 on both human and mouse chromosomes include the receptors for leukemia inhibitory factor, interleukin-7, and prolactin. The Eaat1 locus appears not be linked to the epilepsy mutant stg locus, which is also on chromosome 15. The EAAT1 locus is located in a region of 5p deletions that have been associated with mental retardation and microcephaly. 22 refs., 2 figs.

  13. Hydrophobic amino acids in the hinge region of the 5A apolipoprotein mimetic peptide are essential for promoting cholesterol efflux by the ABCA1 transporter.

    Science.gov (United States)

    Sviridov, Denis O; Andrianov, Alexander M; Anishchenko, Ivan V; Stonik, John A; Amar, Marcelo J A; Turner, Scott; Remaley, Alan T

    2013-01-01

    The bihelical apolipoprotein mimetic peptide 5A effluxes cholesterol from cells and reduces inflammation and atherosclerosis in animal models. We investigated how hydrophobic residues in the hinge region between the two helices are important in the structure and function of this peptide. By simulated annealing analysis and molecular dynamics modeling, two hydrophobic amino acids, F-18 and W-21, in the hinge region were predicted to be relatively surface-exposed and to interact with the aqueous solvent. Using a series of 5A peptide analogs in which F-18 or W-21 was changed to either F, W, A, or E, only peptides with hydrophobic amino acids in these two positions were able to readily bind and solubilize phospholipid vesicles. Compared with active peptides containing F or W, peptides containing E in either of these two positions were more than 10-fold less effective in effluxing cholesterol by the ABCA1 transporter. Intravenous injection of 5A in C57BL/6 mice increased plasma-free cholesterol (5A: 89.9 ± 13.6 mg/dl; control: 38.7 ± 4.3 mg/dl (mean ± S.D.); P < 0.05) and triglycerides (5A: 887.0 ± 172.0 mg/dl; control: 108.9 ± 9.9 mg/dl; P < 0.05), whereas the EE peptide containing E in both positions had no effect. Finally, 5A increased cholesterol efflux approximately 2.5-fold in vivo from radiolabeled macrophages, whereas the EE peptide was inactive. These results provide a rationale for future design of therapeutic apolipoprotein mimetic peptides and provide new insights into the interaction of hydrophobic residues on apolipoproteins with phospholipids in the lipid microdomain created by the ABCA1 transporter during the cholesterol efflux process.

  14. Indigenous amino acids in primitive CR meteorites

    CERN Document Server

    Martins, Z; Orzechowska, G E; Fogel, M L; Ehrenfreund, P

    2008-01-01

    CR meteorites are among the most primitive meteorites. In this paper, we report the first measurements of amino acids in Antarctic CR meteorites, two of which show the highest amino acid concentrations ever found in a chondrite. EET92042, GRA95229 and GRO95577 were analyzed for their amino acid content using high performance liquid chromatography with UV fluorescence detection (HPLC-FD) and gas chromatographymass spectrometry (GC-MS). Our data show that EET92042 and GRA95229 are the most amino acid-rich chondrites ever analyzed, with total amino acid concentrations ranging from 180 parts-per-million (ppm) to 249 ppm. GRO95577, however, is depleted in amino acids. The most abundant amino acids present in the EET92042 and GRA95229 meteorites are the alpha-amino acids glycine, isovaline, alpha-aminoisobutyric acid (alpha-AIB), and alanine, with delta13C values ranging from +31.6per mil to +50.5per mil. The carbon isotope results together with racemic enantiomeric ratios determined for most amino acids strongly i...

  15. Excitatory amino acid transporters: recent insights into molecular mechanisms, novel modes of modulation and new therapeutic possibilities

    DEFF Research Database (Denmark)

    Jensen, Anders A.; Fahlke, Christoph; Bjørn-Yoshimoto, Walden Emil;

    2015-01-01

    into the physiological functions mediated by the different transporter subtypes and their respective therapeutic potential have so far been sparse, in no small part due to the limited selection of pharmacological tools available. In the present update, we outline important new insights into the molecular compositions...... of EAATs and their intricate transport process, the novel approaches to pharmacological modulation of the transporters that have emerged, and interesting new perspectives in EAAT as drug targets proposed in recent years....

  16. α-Amino Acid-Isosteric α-Amino Tetrazoles.

    Science.gov (United States)

    Zhao, Ting; Kurpiewska, Katarzyna; Kalinowska-Tłuścik, Justyna; Herdtweck, Eberhardt; Dömling, Alexander

    2016-02-24

    The synthesis of all 20 common natural proteinogenic and 4 otherα-amino acid-isosteric α-amino tetrazoles has been accomplished, whereby the carboxyl group is replaced by the isosteric 5-tetrazolyl group. The short process involves the use of the key Ugi tetrazole reaction followed by deprotection chemistries. The tetrazole group is bioisosteric to the carboxylic acid and is widely used in medicinal chemistry and drug design. Surprisingly, several of the common α-amino acid-isosteric α-amino tetrazoles are unknown up to now. Therefore a rapid synthetic access to this compound class and non-natural derivatives is of high interest to advance the field. PMID:26817531

  17. Amino acid composition of some Mexican foods.

    Science.gov (United States)

    Morales de León, Josefina; Camacho, M Elena; Bourges, Héctor

    2005-06-01

    Knowledge of the amino acid composition of foods is essential to calculate their chemical score, which is used to predict protein quality of foods and diets. Though amino acid composition of many foods is reasonably well established, better knowledge is needed on native foods consumed in different regions and countries. This paper presents the amino acid composition of different presentations of raw and processed foods produced and consumed in Mexico. The amino acid composition was determined using Beckman amino acid analyzers (models 116 and 6300). Tryptophan was determined using the Spies and Chambers method. Of the different foods analyzed, some comments are made on native or basic foods in Mexico: Spirulin, where lysine is the limiting amino acid, with a chemical score of 67%, is a good source of tryptophan (1.16g/16 gN); amaranth contains high levels of sulphur amino acids (4.09 to 5.34 g/16gN), with a protein content of 15 g/100g; and pulque, a Pre-Hispanic beverage that contains high levels of tryptophan (2.58 g/16 gN) and sulphur amino acids (2.72 g/16 gN). Finally, insects are good sources of sulphur amino acids and lysine.

  18. Substrate-Induced Ubiquitylation and Endocytosis of Yeast Amino Acid Permeases

    OpenAIRE

    Ghaddar, Kassem; Merhi, Ahmad; Saliba, Elie; Krammer, Eva-Maria; Prévost, Martine; André, Bruno

    2014-01-01

    Many plasma membrane transporters are downregulated by ubiquitylation, endocytosis, and delivery to the lysosome in response to various stimuli. We report here that two amino acid transporters of Saccharomyces cerevisiae, the general amino acid permease (Gap1) and the arginine-specific permease (Can1), undergo ubiquitin-dependent downregulation in response to their substrates and that this downregulation is not due to intracellular accumulation of the transported amino acids but to transport ...

  19. Novel amino acids: synthesis of furoxan and sydnonimine containing amino acids and peptides as potential nitric oxide releasing motifs.

    Science.gov (United States)

    Nortcliffe, Andrew; Botting, Nigel P; O'Hagan, David

    2013-07-28

    The incorporation of furoxan and sydnonimine ring systems into amino acid side chains is demonstrated with the preparation of four novel amino acids which carry these nitric oxide-releasing motifs. N-((4-Nitrophenoxy)carbonyl)-3-phenylsydnonimine 9 and bis(phenylsulfonyl)furoxan 10 are the key intermediates for introducing the heterocycle side chains onto appropriate amine and alcohol functionalities respectively. Furoxan 5 and 7 both displayed NO release based on determination of nitrite production. Orthogonal amino acid protecting group strategies were deployed to demonstrate that the amino acids could be incorporated into peptide frameworks. By way of demonstration the amino acids were placed centrally into several tripeptide motifs. Griess test assays showed that these amino acids released NO in the presence of γ-glutathione (GST). PMID:23753002

  20. Relationship between amino acid usage and amino acid evolution in primates.

    Science.gov (United States)

    Liu, Haoxuan; Xie, Zhengqing; Tan, Shengjun; Zhang, Xiaohui; Yang, Sihai

    2015-02-25

    Amino acid usage varies from species to species. A previous study has found a universal trend in amino acid gain and loss in many taxa and a one-way model of amino acid evolution in which the number of new amino acids increases as the number of old amino acids decreases was proposed. Later studies showed that this pattern of amino acid gain and loss is likely to be compatible with the neutral theory. The present work aimed to further study this problem by investigating the evolutionary patterns of amino acids in 8 primates (the nucleotide and protein alignments are available online http://gattaca.nju.edu.cn/pub_data.html). First, the number of amino acids gained and lost was calculated and the evolution trend of each amino acid was inferred. These values were found to be closely related to the usage of each amino acid. Then we analyzed the mutational trend of amino acid substitution in human using SNPs, this trend is highly correlated with fixation trend only with greater variance. Finally, the trends in the evolution of 20 amino acids were evaluated in human on different time scales, and the increasing rate of 5 significantly increasing amino acids was found to decrease as a function of time elapsed since divergence, and the dS/dN ratio also found to increase as a function of time elapsed since divergence. These results suggested that the observed amino acid substitution pattern is influenced by mutation and purifying selection. In conclusion, the present study shows that usage of amino acids is an important factor capable of influencing the observed pattern of amino acid evolution, and also presented evidences suggesting that the observed universal trend of amino acid gain and loss is compatible with neutral evolution. PMID:25527119

  1. Hereditary folate malabsorption: A positively charged amino acid at position 113 of the proton-coupled folate transporter (PCFT/SLC46A1) is required for folic acid binding

    Energy Technology Data Exchange (ETDEWEB)

    Lasry, Inbal; Berman, Bluma [The Fred Wyszkowski Cancer Research Laboratory, Dept. of Biology, Technion-Israel Institute of Technology, Haifa 32000 (Israel); Glaser, Fabian [Bioinformatics Knowledge Unit, The Lorry I. Lokey Interdisciplinary Center for Life Sciences and Engineering, Technion, Haifa 32000 (Israel); Jansen, Gerrit [Department of Rheumatology, VU University Medical Center, Amsterdam (Netherlands); Assaraf, Yehuda G., E-mail: assaraf@tx.technion.ac.il [The Fred Wyszkowski Cancer Research Laboratory, Dept. of Biology, Technion-Israel Institute of Technology, Haifa 32000 (Israel)

    2009-08-28

    The proton-coupled folate transporter (PCFT/SLC46A1) mediates intestinal folate uptake at acidic pH. Some loss of folic acid (FA) transport mutations in PCFT from hereditary folate malabsorption (HFM) patients cluster in R113, thereby suggesting a functional role for this residue. Herein, unlike non-conservative substitutions, an R113H mutant displayed 80-fold increase in the FA transport Km while retaining parental Vmax, hence indicating a major fall in folate substrate affinity. Furthermore, consistent with the preservation of 9% of parental transport activity, R113H transfectants displayed a substantial decrease in the FA growth requirement relative to mock transfectants. Homology modeling based on the crystal structures of the Escherichia coli transporter homologues EmrD and glycerol-3-phosphate transporter revealed that the R113H rotamer properly protrudes into the cytoplasmic face of the minor cleft normally occupied by R113. These findings constitute the first demonstration that a basic amino acid at position 113 is required for folate substrate binding.

  2. Mechanisms controlling renal hemodynamics and electrolyte excretion during amino acids

    Energy Technology Data Exchange (ETDEWEB)

    Woods, L.L.; Mizelle, H.L.; Montani, J.P.; Hall, J.E.

    1986-08-01

    Our purpose was to investigate the mechanisms by which increased plasma amino acids elevate renal blood flow (RBF) and glomerular filtration rate (GFR). Since transport of amino acids and Na is linked in the proximal tubule, the authors hypothesized that increased amino acids might stimulate proximal tubular Na reabsorption (PR/sub Na/) and thus increase RBF and GFR by a macula densa feedback mechanism. A solution of four amino acids (Ala, Ser, Gly, Pro) was infused intravenously into anesthetized dogs with normal kidneys (NK) and with kidneys in which the tubuloglomerular feedback mechanism was blunted by lowering renal artery pressure (LPK) or blocked by making the kidneys nonfiltering (NFK). In NK, RBF and GFR increased by 35 +/- 4% and 30 +/- 7% after 90 min of amino acid infusion, while PR/sub Na/ (estimated from lithium clearance) and O2 consumption increased by 31 +/- 5% and 29 +/- 5% and distal Na delivery remained relatively constant. Autoregulation of RBF and GFR in response to step deceases in renal artery pressure was impaired during amino acids in NK. The hemodynamic responses to amino acids were abolished in LPK and NFK. Infusion of the nonmetabolized -aminoisobutyric acid into NK produced changes in renal hemodynamics that were similar to the responses observed with the four metabolizable amino acids. These data are consistent with the hypothesis that elevation of plasma amino acids increases RBF and GFR by a mechanism that requires an intact macula densa feedback. Metabolism of the amino acids does not appear to be necessary for these changes to occur.

  3. Design and characterization of auxotrophy-based amino acid biosensors.

    Directory of Open Access Journals (Sweden)

    Felix Bertels

    Full Text Available Efficient and inexpensive methods are required for the high-throughput quantification of amino acids in physiological fluids or microbial cell cultures. Here we develop an array of Escherichia coli biosensors to sensitively quantify eleven different amino acids. By using online databases, genes involved in amino acid biosynthesis were identified that - upon deletion - should render the corresponding mutant auxotrophic for one particular amino acid. This rational design strategy suggested genes involved in the biosynthesis of arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, threonine, tryptophan, and tyrosine as potential genetic targets. A detailed phenotypic characterization of the corresponding single-gene deletion mutants indeed confirmed that these strains could neither grow on a minimal medium lacking amino acids nor transform any other proteinogenic amino acid into the focal one. Site-specific integration of the egfp gene into the chromosome of each biosensor decreased the detection limit of the GFP-labeled cells by 30% relative to turbidometric measurements. Finally, using the biosensors to determine the amino acid concentration in the supernatants of two amino acid overproducing E. coli strains (i.e. ΔhisL and ΔtdcC both turbidometrically and via GFP fluorescence emission and comparing the results to conventional HPLC measurements confirmed the utility of the developed biosensor system. Taken together, our study provides not only a genotypically and phenotypically well-characterized set of publicly available amino acid biosensors, but also demonstrates the feasibility of the rational design strategy used.

  4. Diagnostic usefulness of 18F-FAMT PET and L-type amino acid transporter 1 (LAT1) expression in oral squamous cell carcinoma

    International Nuclear Information System (INIS)

    l-[3-18F]-α-Methyltyrosine (18F-FAMT) was developed as an amino acid tracer for PET imaging to provide better specificity than 2-[18F]fluoro-2-deoxy-d-glucose (18F-FDG) PET for cancer diagnosis. We investigated the diagnostic usefulness of 18F-FAMT in oral squamous cell carcinoma (OSCC). The correlation between tumour uptake of 18F-FAMT and L-type amino acid transporter 1 (LAT1) expression was determined. The study group comprised 68 OSCC patients who underwent both 18F-FAMT and 18F-FDG PET. Resected tumour sections were stained by immunohistochemistry for LAT1, CD98 and Ki-67, and microvessel density was determined in terms of CD34 and p53 expression. The sensitivity of primary tumour detection by 18F-FAMT and 18F-FDG PET was 98 % and 100 %, respectively. The sensitivity, specificity and accuracy of 18F-FAMT PET for detecting malignant lymph nodes were 68 %, 99 % and 97 %, respectively, and equivalent values for 18F-FDG PET were 84 %, 94 % and 94 %, respectively. The specificity and accuracy of 18F-FAMT were significantly higher than those of 18F-FDG. The uptake of 18F-FAMT was significantly correlated with LAT1 expression, cell proliferation and advanced stage. The expression of LAT1 in OSCC cells was closely correlated with CD98 levels, cell proliferation and angiogenesis. 18F-FAMT PET showed higher specificity for detecting malignant lesions than 18F-FDG PET. The uptake of 18F-FAMT by OSCC cells can be determined by the presence of LAT1 expression and tumour cell proliferation. (orig.)

  5. Diagnostic usefulness of {sup 18}F-FAMT PET and L-type amino acid transporter 1 (LAT1) expression in oral squamous cell carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Nobusawa, Aiko [Gunma University Graduate School of Medicine, Department of Stomatology and Maxillofacial Surgery, Maebashi, Gunma (Japan); Gunma University Graduate School of Medicine, Department of Diagnostic Pathology, Maebashi, Gunma (Japan); Kim, Mai [Gunma University Graduate School of Medicine, Department of Stomatology and Maxillofacial Surgery, Maebashi, Gunma (Japan); Gunma University Graduate School of Medicine, Department of Diagnostic Radiology and Nuclear Medicine, Maebashi, Gunma (Japan); Kaira, Kyoichi [Gunma University Graduate School of Medicine, Department of Diagnostic Pathology, Maebashi, Gunma (Japan); Gunma University Hospital, Oncology Center, Maebashi, Gunma (Japan); Miyashita, Go; Negishi, Akihide; Yokoo, Satoshi [Gunma University Graduate School of Medicine, Department of Stomatology and Maxillofacial Surgery, Maebashi, Gunma (Japan); Oriuchi, Noboru; Higuchi, Tetsuya; Tsushima, Yoshito [Gunma University Graduate School of Medicine, Department of Diagnostic Radiology and Nuclear Medicine, Maebashi, Gunma (Japan); Kanai, Yoshikatsu [Osaka University, Division of Bio-system Pharmacology, Graduate School of Medicine, Osaka (Japan); Oyama, Tetsunari [Gunma University Graduate School of Medicine, Department of Diagnostic Pathology, Maebashi, Gunma (Japan)

    2013-10-15

    l-[3-{sup 18}F]-{alpha}-Methyltyrosine ({sup 18}F-FAMT) was developed as an amino acid tracer for PET imaging to provide better specificity than 2-[{sup 18}F]fluoro-2-deoxy-d-glucose ({sup 18}F-FDG) PET for cancer diagnosis. We investigated the diagnostic usefulness of {sup 18}F-FAMT in oral squamous cell carcinoma (OSCC). The correlation between tumour uptake of {sup 18}F-FAMT and L-type amino acid transporter 1 (LAT1) expression was determined. The study group comprised 68 OSCC patients who underwent both {sup 18}F-FAMT and {sup 18}F-FDG PET. Resected tumour sections were stained by immunohistochemistry for LAT1, CD98 and Ki-67, and microvessel density was determined in terms of CD34 and p53 expression. The sensitivity of primary tumour detection by {sup 18}F-FAMT and {sup 18}F-FDG PET was 98 % and 100 %, respectively. The sensitivity, specificity and accuracy of {sup 18}F-FAMT PET for detecting malignant lymph nodes were 68 %, 99 % and 97 %, respectively, and equivalent values for {sup 18}F-FDG PET were 84 %, 94 % and 94 %, respectively. The specificity and accuracy of {sup 18}F-FAMT were significantly higher than those of {sup 18}F-FDG. The uptake of {sup 18}F-FAMT was significantly correlated with LAT1 expression, cell proliferation and advanced stage. The expression of LAT1 in OSCC cells was closely correlated with CD98 levels, cell proliferation and angiogenesis. {sup 18}F-FAMT PET showed higher specificity for detecting malignant lesions than {sup 18}F-FDG PET. The uptake of {sup 18}F-FAMT by OSCC cells can be determined by the presence of LAT1 expression and tumour cell proliferation. (orig.)

  6. Synthesis of Chiral Amino Cyclic Phosphoric Acids

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Chirai amino cyclic phosphoric acids, 5-amino-2-hydroxy-4- (4-nitrophenyl)-l, 3,2-dioxaphospho- rinane 2-oxide and 2-hydroxy-4- (4-methylsulfonylphenyl)-5-phthalimido-1,3,2-dioxaphos phorinane 2-oxide are synthesized in good over yields (64. 2% and 72. 8% respectively) from 2-amino-l-aryl-l,3-propanediols. The different reaction conditions are necessary in hydrolysis reactions of amino cyclic phosphonyl chlorides.

  7. Plasma amino acid relationships during parenteral nutrition.

    Science.gov (United States)

    Wells, F E; Smits, B J

    1980-01-01

    The plasma amino acidfs of 17 patients were studied before and during total parenteral nutrition (TPN). The amino acid (AA) pattern changed similarly for all patients. The AA concentration changes relative to preinfusion (PAER) were the most informative index of change. Two groups of AA were defined, the "branched chain" group (five amino acids) and the "hepatic" group (four amino acids) based on the correlation of PAER values. Comparison of PAER values with the ratio of AA intake to requirement indicated that the requirements of the sick patients were more similar to those of children than those of healthy adults.

  8. Formation of Amino Acid Thioesters for Prebiotic Peptide Synthesis: Catalysis By Amino Acid Products

    Science.gov (United States)

    Weber, Arthur L.; DeVincenzi, Donald L. (Technical Monitor)

    1999-01-01

    The origin of life can be described as a series of events in which a prebiotic chemical process came increasingly under the control of its catalytic products. In our search for this prebiotic process that yielded catalytic takeover products (such as polypeptides), we have been investigating a reaction system that generates peptide-forming amino acid thioesters from formaldehyde, glycolaldehyde, and ammonia in the presence of thiols. As shown below, this model process begins by aldol condensation of formaldehyde and glycolaldehyde to give trioses and releases. These sugars then undergo beta-dehydration yielding their respective alpha-ketoaldehydes. Addition of ammonia to the alpha-ketoaldehydes yields imines which can either: (a) rearrange in the presence of thesis to give amino acid thioesters or (be react with another molecule of aldehyde to give imidazoles. This 'one-pot' reaction system operates under mild aqueous conditions, and like modem amino acid biosynthesis, uses sugar intermediates which are converted to products by energy-yielding redox reactions. Recently, we discovered that amino acids, such as the alanine reaction product, catalyze the first and second steps of the process. In the presence of ammonia the process also generates other synthetically useful products, like the important biochemical -- pyruvic acid.

  9. Microbial production of natural poly amino acid

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Three kinds of poly amino acids, poly-γ-glutamic acid, poly(ε-L-lysine) and multi-L-arginyl-poly (L-aspartic acid) can be synthesized by enzymatic process independently from ribosomal protein biosynthesis pathways in microorganism. These biosynthesized polymers have attracted more and more attentions because of their unique properties and various applications. In this review, the current knowledge on the biosynthesis, biodegradations and applications of these three poly amino acids are summarized.

  10. Human Protein and Amino Acid Requirements.

    Science.gov (United States)

    Hoffer, L John

    2016-05-01

    Human protein and amino acid nutrition encompasses a wide, complex, frequently misunderstood, and often contentious area of clinical research and practice. This tutorial explains the basic biochemical and physiologic principles that underlie our current understanding of protein and amino acid nutrition. The following topics are discussed: (1) the identity, measurement, and essentiality of nutritional proteins; (2) the definition and determination of minimum requirements; (3) nutrition adaptation; (4) obligatory nitrogen excretion and the minimum protein requirement; (5) minimum versus optimum protein intakes; (6) metabolic responses to surfeit and deficient protein intakes; (7) body composition and protein requirements; (8) labile protein; (9) N balance; (10) the principles of protein and amino acid turnover, including an analysis of the controversial indicator amino acid oxidation technique; (11) general guidelines for evaluating protein turnover articles; (12) amino acid turnover versus clearance; (13) the protein content of hydrated amino acid solutions; (14) protein requirements in special situations, including protein-catabolic critical illness; (15) amino acid supplements and additives, including monosodium glutamate and glutamine; and (16) a perspective on the future of protein and amino acid nutrition research. In addition to providing practical information, this tutorial aims to demonstrate the importance of rigorous physiologic reasoning, stimulate intellectual curiosity, and encourage fresh ideas in this dynamic area of human nutrition. In general, references are provided only for topics that are not well covered in modern textbooks. PMID:26796095

  11. 6th Amino Acid Assessment Workshop

    Science.gov (United States)

    The focus of the 6th workshop is on lysine, arginine, and related amino acids. Functions, metabolic pathways, clinical uses, and upper tolerance intakes are emphasized in the articles that follow. Lysine is arguably the most deficient amino acid in the food supply of countries where poverty exists, ...

  12. Crystalline amino acids and nitrogen emission

    NARCIS (Netherlands)

    Verstegen, M.W.A.; Jongbloed, A.W.

    2003-01-01

    Reductions in dietary protein level and supplementation with certain crystalline amino acids is a well-established method of formulating diets to achieve a more ideal amino acid pattern and to reduce nitrogen excretion. Up to 35% reduction in nitrogen excretion may be achieved by supplementing pig d

  13. The Apollo Program and Amino Acids

    Science.gov (United States)

    Fox, Sidney W.

    1973-01-01

    Discusses the determination of hydrolyzable amino acid precursors and a group of six amino acids in the returned lunar samples of the Apollo programs. Indicates that molecular evolution is arrested at the precursor stage on the Moon because of lack of water. (CC)

  14. 40 CFR 721.10126 - Alkyl amino substituted triazine amino substituted benezenesulfonic acid reaction product with...

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkyl amino substituted triazine amino... substituted triazine amino substituted benezenesulfonic acid reaction product with naphthalenesulfonato azo... substituted triazine amino substituted benezenesulfonic acid reaction product with naphthalenesulfonato...

  15. Sodium-Dependent Transport of Neutral Amino Acids by Whole Cells and Membrane Vesicles of Streptococcus bovis, a Ruminal Bacterium

    NARCIS (Netherlands)

    Russell, James B.; Strobel, Herbert J.; Driessen, Arnold J.M.; Konings, Wilhelmus

    1988-01-01

    Streptococcus bovis JB1 cells were able to transport serine, threonine, or alanine, but only when they were incubated in sodium buffers. If glucose-energized cells were washed in potassium phosphate and suspended in potassium phosphate buffer, there was no detectable uptake. Cells deenergized with 2

  16. Synthesis of β-Amino Acid Derivatives

    Institute of Scientific and Technical Information of China (English)

    Zhao Yonghua; Ma Zhihua; Jiang Nan; Wang Jianbo

    2004-01-01

    In recent years, β-amino acids and their derivatives have attracted considerable attention due to their occurrence in biologically active natural products, such as dolastatins,cyclohexylnorstatine and Taxol. β-Amino acids also find application in the synthesis of β-lactams,piperidines, indolizidines. Moreover, the peptides consisting of β-amino acids, the so-called β-peptides, have been extensively studied recently. Consequently, considerable efforts have been directed to the synthesis of β-amino acids and their derivatives1. In particular, stereoselective synthesis of β-amino acids has been a challenging project, and there are only limited methods available. In this presentation, we report our efforts in this area.

  17. Genetics of Amino Acid Taste and Appetite.

    Science.gov (United States)

    Bachmanov, Alexander A; Bosak, Natalia P; Glendinning, John I; Inoue, Masashi; Li, Xia; Manita, Satoshi; McCaughey, Stuart A; Murata, Yuko; Reed, Danielle R; Tordoff, Michael G; Beauchamp, Gary K

    2016-07-01

    The consumption of amino acids by animals is controlled by both oral and postoral mechanisms. We used a genetic approach to investigate these mechanisms. Our studies have shown that inbred mouse strains differ in voluntary amino acid consumption, and these differences depend on sensory and nutritive properties of amino acids. Like humans, mice perceive some amino acids as having a sweet (sucrose-like) taste and others as having an umami (glutamate-like) taste. Mouse strain differences in the consumption of some sweet-tasting amino acids (d-phenylalanine, d-tryptophan, and l-proline) are associated with polymorphisms of a taste receptor, type 1, member 3 gene (Tas1r3), and involve differential peripheral taste responsiveness. Strain differences in the consumption of some other sweet-tasting amino acids (glycine, l-alanine, l-glutamine, and l-threonine) do not depend on Tas1r3 polymorphisms and so must be due to allelic variation in other, as yet unknown, genes involved in sweet taste. Strain differences in the consumption of l-glutamate may depend on postingestive rather than taste mechanisms. Thus, genes and physiologic mechanisms responsible for strain differences in the consumption of each amino acid depend on the nature of its taste and postingestive properties. Overall, mouse strain differences in amino acid taste and appetite have a complex genetic architecture. In addition to the Tas1r3 gene, these differences depend on other genes likely involved in determining the taste and postingestive effects of amino acids. The identification of these genes may lead to the discovery of novel mechanisms that regulate amino acid taste and appetite. PMID:27422518

  18. Synthesis and anticonvulsant activity of novel bicyclic acidic amino acids

    DEFF Research Database (Denmark)

    Conti, Paola; De Amici, Marco; Joppolo Di Ventimiglia, Samuele;

    2003-01-01

    Bicyclic acidic amino acids (+/-)-6 and (+/-)-7, which are conformationally constrained homologues of glutamic acid, were prepared via a strategy based on a 1,3-dipolar cycloaddition. The new amino acids were tested toward ionotropic and metabotropic glutamate receptor subtypes; both of them...

  19. Effect of egg weight on composition, embryonic growth, and expression of amino acid transporter genes in yolk sac membranes and small intestines of the domestic pigeon (Columba livia).

    Science.gov (United States)

    Chen, M X; Li, X G; Yan, H C; Wang, X Q; Gao, C Q

    2016-06-01

    The objective of this study was to investigate the effect of egg weight on the composition of the egg, the growth of the embryo, and the expression of amino acid transporter genes in the yolk sac membranes and small intestines of the domestic pigeon (Columba livia). A total of 240 fertilized eggs were collected and divided into two groups based on the weight of the eggs, light (LE) and heavy (HE). The composition of 20 eggs from each group was measured, and the remaining eggs were weighed and placed in an incubator. On embryonic days (E) 9, 11, 13, and 15 and day of hatch (DOH), 15 embryos/hatchlings from each group were measured for embryonic growth, and samples were collected. The HE had heavier yolk and albumen weights than the LE (P < 0.01). Compared with the LE, the HE had heavier yolk-free embryonic body and yolk sac weights from E13 to DOH (P < 0.05). Additionally, the HE had larger yolk sac membrane weights from E13 to E15 (P < 0.05) and had more residual yolk sac content on DOH than those of the LE (P < 0.01). The yolk absorption was greater for the HE than for the LE from E11 to E13 (P < 0.05). Furthermore, the abundance of CAT2 and PepT1 mRNA in the yolk sac membranes was greater in the HE than in the LE on E13 (P < 0.05). Compared with the LE, the gene expression of EAAT2 in the intestine on E13 was greater in the HE, whereas the expression of EAAT3 was lower in the HE (P < 0.05). Taken together, our results suggest that egg weight influenced the composition of the eggs, embryonic development, and expression of amino acid transporter genes in the yolk sac membranes and small intestines of pigeon embryos.

  20. Effect of amphetamine on extracellular concentrations of amino acids in striatum in neurotensin subtype 1 and 2 receptor null mice: a possible interaction between neurotensin receptors and amino acid systems for study of schizophrenia

    OpenAIRE

    Li, Zhimin; Liang, Yanqi; Boules, Mona; Gordillo, Andres; Richelson, Elliott

    2010-01-01

    Neurotensin (NT) is a tridecapeptide that acts as a neuromodulator in the central nervous system mainly through two NT receptors: NTS1 and NTS2. The present study was done to determine the roles of NTS1 and NTS2 on amino acid release in striatum with the use of NTS1 or NTS2 knock-out (-/-) mice given d-amphetamine. Both NTS1-/- and NTS2-/- mice had lower extracellular concentrations of D-serine in striatum than did wild type (WT) mice. NTS2-/- but not NTS1-/- mice also had significantly lower...

  1. Amino acid analogs for tumor imaging

    Science.gov (United States)

    Goodman, M.M.; Shoup, T.

    1998-09-15

    The invention provides novel amino acid compounds of use in detecting and evaluating brain and body tumors. These compounds combine the advantageous properties of 1-amino-cycloalkyl-1-carboxylic acids, namely, their rapid uptake and prolonged retention in tumors with the properties of halogen substituents, including certain useful halogen isotopes including fluorine-18, iodine-123, iodine-125, iodine-131, bromine-75, bromine-76, bromine-77 and bromine-82. In one aspect, the invention features amino acid compounds that have a high specificity for target sites when administered to a subject in vivo. Preferred amino acid compounds show a target to non-target ratio of at least 5:1, are stable in vivo and substantially localized to target within 1 hour after administration. An especially preferred amino acid compound is [{sup 18}F]-1-amino-3-fluorocyclobutane-1-carboxylic acid (FACBC). In another aspect, the invention features pharmaceutical compositions comprised of an {alpha}-amino acid moiety attached to either a four, five, or a six member carbon-chain ring. In addition, the invention features analogs of {alpha}-aminoisobutyric acid.

  2. Amino acid analogs for tumor imaging

    Energy Technology Data Exchange (ETDEWEB)

    Goodman, Mark M. (Atlanta, GA); Shoup, Timothy (Decatur, GA)

    1998-09-15

    The invention provides novel amino acid compounds of use in detecting and evaluating brain and body tumors. These compounds combine the advantageous properties of 1-amino-cycloalkyl-1-carboxylic acids, namely, their rapid uptake and prolonged retention in tumors with the properties of halogen substituents, including certain useful halogen isotopes including fluorine-18, iodine-123, iodine-125, iodine-131, bromine-75, bromine-76, bromine-77 and bromine-82. In one aspect, the invention features amino acid compounds that have a high specificity for target sites when administered to a subject in vivo. Preferred amino acid compounds show a target to non-target ratio of at least 5:1, are stable in vivo and substantially localized to target within 1 hour after administration. An especially preferred amino acid compound is ›.sup.18 F!-1-amino-3-fluorocyclobutane-1-carboxylic acid (FACBC). In another aspect, the invention features pharmaceutical compositions comprised of an .alpha.-amino acid moiety attached to either a four, five, or a six member carbon-chain ring. In addition, the invention features analogs of .alpha.-aminoisobutyric acid.

  3. Amino acid analogs for tumor imaging

    Energy Technology Data Exchange (ETDEWEB)

    Goodman, Mark M. (Atlanta, GA); Shoup, Timothy (Decatur, GA)

    1998-10-06

    The invention provides novel amino acid compounds of use in detecting and evaluating brain and body tumors. These compounds combine the advantageous properties of 1-amino-cycloalkyl-1-carboxylic acids, namely, their rapid uptake and prolonged retention in tumors with the properties of halogen substituents, including certain useful halogen isotopes including fluorine-18, iodine-123, iodine-125, iodine-131, bromine-75, bromine-76, bromine-77 and bromine-82. In one aspect, the invention features amino acid compounds that have a high specificity for target sites when administered to a subject in vivo. Preferred amino acid compounds show a target to non-target ratio of at least 5:1, are stable in vivo and substantially localized to target within 1 hour after administration. An especially preferred amino acid compound is ›.sup.18 F!-1-amino-3-fluorocyclobutane-1-carboxylic acid (FACBC). In another aspect, the invention features pharmaceutical compositions comprised of an .alpha.-amino acid moiety attached to either a four, five, or a six member carbon-chain ring. In addition, the invention features analogs of .alpha.-aminoisobutyric acid.

  4. Amino acid analogs for tumor imaging

    Energy Technology Data Exchange (ETDEWEB)

    Goodman, M.M.; Shoup, T.

    1998-10-06

    The invention provides novel amino acid compounds of use in detecting and evaluating brain and body tumors. These compounds combine the advantageous properties of 1-amino-cycloalkyl-1-carboxylic acids, namely, their rapid uptake and prolonged retention in tumors with the properties of halogen substituents, including certain useful halogen isotopes including fluorine-18, iodine-123, iodine-125, iodine-131, bromine-75, bromine-76, bromine-77 and bromine-82. In one aspect, the invention features amino acid compounds that have a high specificity for target sites when administered to a subject in vivo. Preferred amino acid compounds show a target to non-target ratio of at least 5:1, are stable in vivo and substantially localized to target within 1 hour after administration. An especially preferred amino acid compound is [{sup 18}F]-1-amino-3-fluorocyclobutane-1-carboxylic acid (FACBC). In another aspect, the invention features pharmaceutical compositions comprised of an {alpha}-amino acid moiety attached to either a four, five, or a six member carbon-chain ring. In addition, the invention features analogs of {alpha}-aminoisobutyric acid.

  5. Regulation of intestinal protein metabolism by amino acids.

    Science.gov (United States)

    Bertrand, Julien; Goichon, Alexis; Déchelotte, Pierre; Coëffier, Moïse

    2013-09-01

    Gut homeostasis plays a major role in health and may be regulated by quantitative and qualitative food intake. In the intestinal mucosa, an intense renewal of proteins occurs, at approximately 50% per day in humans. In some pathophysiological conditions, protein turnover is altered and may contribute to intestinal or systemic diseases. Amino acids are key effectors of gut protein turnover, both as constituents of proteins and as regulatory molecules limiting intestinal injury and maintaining intestinal functions. Many studies have focused on two amino acids: glutamine, known as the preferential substrate of rapidly dividing cells, and arginine, another conditionally essential amino acid. The effects of glutamine and arginine on protein synthesis appear to be model and condition dependent, as are the involved signaling pathways. The regulation of gut protein degradation by amino acids has been minimally documented until now. This review will examine recent data, helping to better understand how amino acids regulate intestinal protein metabolism, and will explore perspectives for future studies.

  6. Vigabatrin absorption is mediated via the proton-coupled amino acid transporter PAT1 – in vitro and in vivo

    DEFF Research Database (Denmark)

    Nøhr, Martha Kampp; Juul, Rasmus Vestergaard; Hansen, Steen Honore';

    2013-01-01

    The absorption of vigabatrin was investigated using Caco-2 cell monolayers and Sprague Dawley rats as an in vitro and in vivo model, respectively. LC-MS or LC-MS/MS was applied for the quantification. Results The permeability of vigabatrin in Caco-2 cell monolayers was increased at apical pH 6.0 compared to pH 7.......4. The transepithelial transport across Caco-2 cell monolayers was polarized in the lumen-to-blood direction in the presence of a proton gradient. The presence of PAT1-ligands significantly decreased the permeability of vigabatrin across Caco-2 cell monolayers. In Sprague Dawley rats the presence of PAT1-ligands altered...

  7. YjeH Is a Novel Exporter of l-Methionine and Branched-Chain Amino Acids in Escherichia coli.

    Science.gov (United States)

    Liu, Qian; Liang, Yong; Zhang, Yun; Shang, Xiuling; Liu, Shuwen; Wen, Jifu; Wen, Tingyi

    2015-11-01

    Amino acid efflux transport systems have important physiological functions and play vital roles in the fermentative production of amino acids. However, no methionine exporter has yet been identified in Escherichia coli. In this study, we identified a novel amino acid exporter, YjeH, in E. coli. The yjeH overexpression strain exhibited high tolerance to the structural analogues of l-methionine and branched-chain amino acids, decreased intracellular amino acid levels, and enhanced export rates in the presence of a Met-Met, Leu-Leu, Ile-Ile, or Val-Val dipeptide, suggesting that YjeH functions as an exporter of l-methionine and the three branched-chain amino acids. The export of the four amino acids in the yjeH overexpression strain was competitively inhibited in relation to each other. The expression of yjeH was strongly induced by increasing cytoplasmic concentrations of substrate amino acids. Green fluorescent protein (GFP)-tagged YjeH was visualized by total internal reflection fluorescence microscopy to confirm the plasma membrane localization of YjeH. Phylogenetic analysis of transporters indicated that YjeH belongs to the amino acid efflux family of the amino acid/polyamine/organocation (APC) superfamily. Structural modeling revealed that YjeH has the typical "5 + 5" transmembrane α-helical segment (TMS) inverted-repeat fold of APC superfamily transporters, and its binding sites are strictly conserved. The enhanced capacity of l-methionine export by the overexpression of yjeH in an l-methionine-producing strain resulted in a 70% improvement in titer. This study supplements the transporter classification and provides a substantial basis for the application of the methionine exporter in metabolic engineering.

  8. Distribution of Amino Acids in Lunar Regolith

    Science.gov (United States)

    Elsila, J. E.; Callahan, M. P.; Glavin, D. P.; Dworkin, J. P.; Noble, S. K.; Gibson, E. K., Jr.

    2014-01-01

    One of the most eagerly studied questions upon initial return of lunar samples was whether significant amounts of organic compounds, including amino acids, were present. Analyses during the 1970s produced only tentative and inconclusive identifications of indigenous amino acids. Those analyses were hampered by analytical difficulties including relative insensitivity to certain compounds, the inability to separate chiral enantiomers, and the lack of compound-specific isotopic measurements, which made it impossible to determine whether the detected amino acids were indigenous to the lunar samples or the results of contamination. Numerous advances have been made in instrumentation and methodology for amino acid characterization in extraterrestrial samples in the intervening years, yet the origin of amino acids in lunar regolith samples has been revisited only once for a single lunar sample, (3) and remains unclear. Here, we present initial data from the analyses of amino acid abundances in 12 lunar regolith samples. We discuss these abundances in the context of four potential amino acid sources: (1) terrestrial biological contamination; (2) contamination from lunar module (LM) exhaust; (3) derivation from solar windimplanted precursors; and (4) exogenous delivery from meteorites.

  9. Enantiomer-specific selection of amino acids.

    Science.gov (United States)

    Ren, Xueying; Tellez, Luis A; de Araujo, Ivan E

    2013-12-01

    Dietary intake of L-amino acids impacts on several physiological functions, including the control of gastrointestinal motility, pancreatic secretion, and appetite. However, the biological mechanisms regulating behavioral predilections for certain amino acid types remain poorly understood. We tested the hypothesis that, in mice, the potency with which a given glucogenic amino acid increases glucose utilization reflects its rewarding properties. We have found that: (1) during long-, but not short-, term preference tests, L-alanine and L-serine were preferred over their D-enantiomer counterparts, while no such effect was observed for L-threonine vs. D-threonine; (2) these behavioral patterns were closely associated with the ability of L-amino acids to promote increases in respiratory exchange ratios such that those, and only those, L-amino acids able to promote increases in respiratory exchange ratios were preferred over their D-isomers; (3) these behavioral preferences were independent of gustatory influences, since taste-deficient Trpm5 knockout mice displayed ingestive responses very similar to those of their wild-type counterparts. We conclude that the ability to promote increases in respiratory exchange ratios enhances the reward value of nutritionally relevant amino acids and suggest a mechanistic link between substrate utilization and amino acid preferences.

  10. Ionotropic excitatory amino acid receptor ligands. Synthesis and pharmacology of a new amino acid AMPA antagonist

    DEFF Research Database (Denmark)

    Madsen, U; Sløk, F A; Stensbøl, T B;

    2000-01-01

    We have previously described the potent and selective (RS)-2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid (AMPA) receptor agonist, (RS)-2-amino-3-(3-carboxy-5-methyl-4-isoxazolyl)propionic acid (ACPA), and the AMPA receptor antagonist (RS)-2-amino-3-[3-(carboxymethoxy)-5-methyl-4-isoxa...

  11. Determining important regulatory relations of amino acids from dynamic network analysis of plasma amino acids.

    Science.gov (United States)

    Shikata, Nahoko; Maki, Yukihiro; Nakatsui, Masahiko; Mori, Masato; Noguchi, Yasushi; Yoshida, Shintaro; Takahashi, Michio; Kondo, Nobuo; Okamoto, Masahiro

    2010-01-01

    The changes in the concentrations of plasma amino acids do not always follow the flow-based metabolic pathway network. We have previously shown that there is a control-based network structure among plasma amino acids besides the metabolic pathway map. Based on this network structure, in this study, we performed dynamic analysis using time-course data of the plasma samples of rats fed single essential amino acid deficient diet. Using S-system model (conceptual mathematical model represented by power-law formalism), we inferred the dynamic network structure which reproduces the actual time-courses within the error allowance of 13.17%. By performing sensitivity analysis, three of the most dominant relations in this network were selected; the control paths from leucine to valine, from methionine to threonine, and from leucine to isoleucine. This result is in good agreement with the biological knowledge regarding branched-chain amino acids, and suggests the biological importance of the effect from methionine to threonine.

  12. Deletion of a gene encoding an amino acid transporter in the midgut membrane causes resistance to a Bombyx parvo-like virus.

    Science.gov (United States)

    Ito, Katsuhiko; Kidokoro, Kurako; Sezutsu, Hideki; Nohata, Junko; Yamamoto, Kimiko; Kobayashi, Isao; Uchino, Keiro; Kalyebi, Andrew; Eguchi, Ryokitsu; Hara, Wajiro; Tamura, Toshiki; Katsuma, Susumu; Shimada, Toru; Mita, Kazuei; Kadono-Okuda, Keiko

    2008-05-27

    Bombyx mori densovirus type 2 (BmDNV-2), a parvo-like virus, replicates only in midgut columnar cells and causes fatal disease. The resistance expressed in some silkworm strains against the virus is determined by a single gene, nsd-2, which is characterized as nonsusceptibility irrespective of the viral dose. However, the responsible gene has been unknown. We isolated the nsd-2 gene by positional cloning. The virus resistance is caused by a 6-kb deletion in the ORF of a gene encoding a 12-pass transmembrane protein, a member of an amino acid transporter family, and expressed only in midgut. Germ-line transformation with a wild-type transgene expressed in the midgut restores susceptibility, showing that the defective membrane protein is responsible for resistance. Cumulatively, our data show that the membrane protein is a functional receptor for BmDNV-2. This is a previously undescribed report of positional cloning of a mutant gene in Bombyx and isolation of an absolute virus resistance gene in insects. PMID:18495929

  13. Amino Acid Profile of Some New Vartieties of Oil Seeds

    Directory of Open Access Journals (Sweden)

    Satish Ingale and S.K. Shrivastava

    2011-04-01

    Full Text Available There are large varieties of oil seeds and legumes in India, which are part of traditional food system but whose nutritional and economic values have not been completely determine and are far less exploited for both human and livestock utilization. The objective of this study was to evaluate Sunflower (Helianths annuus LSF-11, Sunflower (Helianths annuus LSF-8, Safflower (Carthamus tinctorius PBNS-12, Safflower (Carthamus tinctorius PBNS-40, and Ground nut (Arachis hypogaea JL-24 seeds with the aim of qualifying and quantifying chemical information that might serve as a guide to exploit its potentials and benefits for human and animal nutrition. The amino acid profile of these oil seed were carried out using standard methods. Amino acid analysis using technical sequential multisampling amino acid analyzer detected all essential and non essential amino acids. The seeds are rich in four amino acids (EAA and NEAA (g/16g N Glutamic acid (5.083, Aspartic acid (3.459, Proline (6.412 and Methionine (3.001%, respectively. The other amino acids compared well with the FAO reference protein, Serine appeared to be the most limiting amino acid percent. Based on results of this study, the lesser known and under-utilized oil seeds, they can be a potential source and energy supplements in livestock feed.

  14. Regulation of amino acid transporters by adenoviral-mediated human insulin-like growth factor-1 in a mouse model of placental insufficiency in vivo and the human trophoblast line BeWo in vitro

    Science.gov (United States)

    Jones, H.; Crombleholme, T.; Habli, M.

    2014-01-01

    Previous work in our laboratory demonstrated that over-expression of human insulin-like growth factor-11 (hIGF-1) in the placenta corrects fetal weight deficits in mouse, rat, and rabbit models of intrauterine growth restriction without changes in placental weight. The underlying mechanisms of this effect have not been elucidated. To investigate the effect of intra-placental IGF-1 over-expression on placental function we examined amino acid transporter expression and localization in both a mouse model of placental Insufficiency (PI) and a model of human trophoblast, the BeWo Choriocarcinoma cell line. For in vitro human studies, BeWo Choriocarcinoma cells were maintained in F12 complete medium + 10%FBS. Cells were incubated in serum-free control media ± Ad-IGF-1 or Ad-LacZ for 48 h. MOIs of 10:1 and 100:1 were utilized. In BeWo, transfection efficiency was 100% at an MOI of 100:1 and Ad-IGF-1 significantly increased IGF-1 secretion, proliferation and invasion but reduced apoptosis compared to controls. In vitro, amino acid uptake was increased following Ad-IGF-1 treatment and associated with significantly increased RNA expression of SNAT1, 2, LAT1 and 4F2hc. Only SNAT2 protein expression was increased but LAT1 showed relocalization from a perinuclear location to the cytoplasm and cell membrane. For in vivo studies, timed-pregnant animals were divided into four groups on day 18; sham-operated controls, uterine artery branch ligation (UABL), UABL + Ad-hIGF-1 (108 PFU), UABL + Ad-LacZ (108 PFU). At gestational day 20, pups and placentas were harvested by C-section. Only LAT1 mRNA expression changed, showing that a reduced expression of the transporter levels in the PI model could be partially rectified with Ad-hIGF1 treatment. At the protein level, System L was reduced in PI but remained at control levels following Ad-hIGF1. The System A isoforms were differentially regulated with SNAT2 expression diminished but SNAT1 increased in PI and Ad-hIGF1 groups. Enhanced

  15. N-13 labeled amino acids: biodistribution, metabolism and dosimetric considerations

    International Nuclear Information System (INIS)

    With the growing interest in metabolic imaging and with the increasing number of cyclotron/PET facilities, more studies are being performed in animal and humans using short-lived positron-emitting radionuclides. Amino acids labeled either with N-13 or C-11 are one group of compounds being used to study in vivo regional organ (i.e., brain and heart) or tumor metabolism. Of the studies previously reported using C-11 or N-13 labeled amino acids (methionine, alanine, valine, glutamate, glutamine and tryptophan), imaging was restricted mainly to the organ or tissue of interest with little information obtained about the whole-bode distribution of the label. Such data are important for studying interorgan transport of amino acids and for determining accurate dosimetric measurements after intravenous injection of labeled amino acids. The goals of the authors study were to compare the distribution of several N-13 L-amino acids and N-13 ammonia in tumor-bearing mice and to determine the metabolic fate of the label in vivo. The following amino acids were enzymatically labeled using N-13 ammonia: glutamine, glutamate, methionine, α-aminobutyric acid, valine and leucine. 30 references, 2 figures, 14 tables

  16. Uptake of 3-[125I]iodo-α-methyl-L-tyrosine into colon cancer DLD-1 cells: characterization and inhibitory effect of natural amino acids and amino acid-like drugs

    International Nuclear Information System (INIS)

    Introduction: We examined 3-[123I]iodo-α-methyl-L-tyrosine ([123I]IMT) uptake and inhibition by amino acids and amino acid-like drugs in the human DLD-1 colon cancer cell line, to discuss correlation between the inhibition effect and structure. Methods: Expression of relevant neutral amino acid transporters was examined by real-time PCR with DLD-1 cells. The time course of [125I]IMT uptake, contributions of transport systems, concentration dependence and inhibition effects by amino acids and amino acid-like drugs (1 mM) on [125I]IMT uptake were examined. Results: Expression of system L (4F2hc, LAT1 and LAT2), system A (ATA1, ATA2) and system ASC (ASCT1) was strongly detected; system L (LAT3, LAT4) and MCT8 were weakly detected; and B0AT was not detected. [125I]IMT uptake in DLD-1 cells involved Na+-independent system L primarily and Na+-dependent system(s). Uptake of [125I]IMT in Na+-free buffer followed Michaelis-Menten kinetics, with a Km of 78 μM and Vmax of 333 pmol/106 cells per minute. Neutral D- and L-amino acids with branched or aromatic large side chains inhibited [125I]IMT uptake. Tyrosine analogues, tryptophan analogues, L-phenylalanine and p-halogeno-L-phenylalanines, and gamma amino acids [including 3,4-dihydroxy-L-phenylalanine (L-DOPA), DL-threo-β-(3,4-dihydroxyphenyl)serine (DOPS), 4-[bis(2-chloroethyl)amino]-L-phenylalanine and 1-(aminomethyl)-cyclohexaneacetic acid] strongly inhibited [125I]IMT uptake, but L-tyrosine methyl ester and R(+)/S(-)-baclofen weakly inhibited uptake. The substrates of system ASC and A did not inhibit [125I]IMT uptake except L-serine and D/L-cysteine. Conclusions: [125I]IMT uptake in DLD-1 cells involves mostly LAT1 and its substrates' (including amino acid-like drugs derived from tyrosine, tryptophan and phenylalanine) affinity to transport via LAT1. Whether transport of gamma amino acid analogues is involved in LAT1 depends on the structure of the group corresponding to the amino acid residue. Beta-hydroxylation may

  17. Uptake of 3-[{sup 125}I]iodo-{alpha}-methyl-L-tyrosine into colon cancer DLD-1 cells: characterization and inhibitory effect of natural amino acids and amino acid-like drugs

    Energy Technology Data Exchange (ETDEWEB)

    Shikano, Naoto [Department of Radiological Sciences, Ibaraki Prefectural University of Health Sciences, Ami-machi, Inashiki-gun, Ibaraki 300-0394 (Japan)], E-mail: sikano@ipu.ac.jp; Ogura, Masato [Department of Radiological Sciences, Ibaraki Prefectural University of Health Sciences, Ami-machi, Inashiki-gun, Ibaraki 300-0394 (Japan); Okudaira, Hiroyuki [School of Health Sciences, Faculty of Medicine, Kanazawa University, Kanazawa 920-0942 (Japan); Nakajima, Syuichi; Kotani, Takashi [Department of Radiological Sciences, Ibaraki Prefectural University of Health Sciences, Ami-machi, Inashiki-gun, Ibaraki 300-0394 (Japan); Kobayashi, Masato [School of Health Sciences, Faculty of Medicine, Kanazawa University, Kanazawa 920-0942 (Japan); Nakazawa, Shinya [Department of Radiological Sciences, Ibaraki Prefectural University of Health Sciences, Ami-machi, Inashiki-gun, Ibaraki 300-0394 (Japan); Baba, Takeshi; Yamaguchi, Naoto [Center for Medical Sciences, Ibaraki Prefectural University of Health Sciences, Ami-machi, Inashiki-gun, Ibaraki 300-0394 (Japan); Kubota, Nobuo [Department of Radiological Sciences, Ibaraki Prefectural University of Health Sciences, Ami-machi, Inashiki-gun, Ibaraki 300-0394 (Japan); Iwamura, Yukio [Center for Humanities and Sciences, Ibaraki Prefectural University of Health Sciences, Ami-machi, Inashiki-gun, Ibaraki 300-0394 (Japan); Kawai, Keiichi [School of Health Sciences, Faculty of Medicine, Kanazawa University, Kanazawa 920-0942 (Japan)

    2010-02-15

    Introduction: We examined 3-[{sup 123}I]iodo-{alpha}-methyl-L-tyrosine ([{sup 123}I]IMT) uptake and inhibition by amino acids and amino acid-like drugs in the human DLD-1 colon cancer cell line, to discuss correlation between the inhibition effect and structure. Methods: Expression of relevant neutral amino acid transporters was examined by real-time PCR with DLD-1 cells. The time course of [{sup 125}I]IMT uptake, contributions of transport systems, concentration dependence and inhibition effects by amino acids and amino acid-like drugs (1 mM) on [{sup 125}I]IMT uptake were examined. Results: Expression of system L (4F2hc, LAT1 and LAT2), system A (ATA1, ATA2) and system ASC (ASCT1) was strongly detected; system L (LAT3, LAT4) and MCT8 were weakly detected; and B{sup 0}AT was not detected. [{sup 125}I]IMT uptake in DLD-1 cells involved Na{sup +}-independent system L primarily and Na{sup +}-dependent system(s). Uptake of [{sup 125}I]IMT in Na{sup +}-free buffer followed Michaelis-Menten kinetics, with a K{sub m} of 78 {mu}M and V{sub max} of 333 pmol/10{sup 6} cells per minute. Neutral D- and L-amino acids with branched or aromatic large side chains inhibited [{sup 125}I]IMT uptake. Tyrosine analogues, tryptophan analogues, L-phenylalanine and p-halogeno-L-phenylalanines, and gamma amino acids [including 3,4-dihydroxy-L-phenylalanine (L-DOPA), DL-threo-{beta}-(3,4-dihydroxyphenyl)serine (DOPS), 4-[bis(2-chloroethyl)amino]-L-phenylalanine and 1-(aminomethyl)-cyclohexaneacetic acid] strongly inhibited [{sup 125}I]IMT uptake, but L-tyrosine methyl ester and R(+)/S(-)-baclofen weakly inhibited uptake. The substrates of system ASC and A did not inhibit [{sup 125}I]IMT uptake except L-serine and D/L-cysteine. Conclusions: [{sup 125}I]IMT uptake in DLD-1 cells involves mostly LAT1 and its substrates' (including amino acid-like drugs derived from tyrosine, tryptophan and phenylalanine) affinity to transport via LAT1. Whether transport of gamma amino acid analogues is

  18. Effect of amino acids and amino acid derivatives on crystallization of hemoglobin and ribonuclease A

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Len, E-mail: len@ksc.kwansei.ac.jp; Kobayashi, Toyoaki [School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337 (Japan); Shiraki, Kentaro [Institute of Applied Physics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan); Yamaguchi, Hiroshi [School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337 (Japan)

    2008-05-01

    The effect of the addition of amino acids and amino acid derivatives on the crystallization of hemoglobin and ribonuclease A has been evaluated. The results showed that certain types of additives expand the concentration conditions in which crystals are formed. Determination of the appropriate conditions for protein crystallization remains a highly empirical process. Preventing protein aggregation is necessary for the formation of single crystals under aggregation-prone solution conditions. Because many amino acids and amino acid derivatives offer a unique combination of solubility and stabilizing properties, they open new avenues into the field of protein aggregation research. The use of amino acids and amino acid derivatives can potentially influence processes such as heat treatment and refolding reactions. The effect of the addition of several amino acids, such as lysine, and several amino acid derivatives, such as glycine ethyl ester and glycine amide, on the crystallization of equine hemoglobin and bovine pancreatic ribonuclease A has been examined. The addition of these amino acids and amino acid derivatives expanded the range of precipitant concentration in which crystals formed without aggregation. The addition of such additives appears to promote the crystallization of proteins.

  19. Clinical significance of L-type amino acid transporter 1 expression as a prognostic marker and potential of new targeting therapy in biliary tract cancer

    International Nuclear Information System (INIS)

    The expression of L-type amino acid transporter 1 (LAT1) has been described to play essential roles in tumor cell growth and survival. However, it remains unclear about the clinicopathological significance of LAT1 expression in biliary tract cancer. This study was conducted to determine biological significance of LAT1 expression and investigate whether LAT1 could be a prognostic biomarker for biliary tract cancer. A total of 139 consecutive patients with resected pathologic stage I-IV biliary tract adenocarcinoma were retrospectively reviewed. Tumor specimens were stained by immunohistochemistry for LAT1, Ki-67, microvessel density determined by CD34, and p53; and prognosis of patients was correlated. Biological significance of LAT1 expression was investigated by in vitro and in vivo experiments with LAT inhibitor, 2-aminobicyclo-(2,2,1)-heptane-2-carboxylic acid (BCH) using cholangiocarcinoma cell line. In total patients, high LAT1 expressions were recognized in 64.0%. The expression of LAT1 was closely correlated with lymphatic metastases, cell proliferation and angiogenesis, and was a significant indicator for predicting poor outcome after surgery. LAT1 expression was a significant independent predictor by multivariate analysis. Both in vitro and in vivo preliminary experiments indicated that BCH significantly suppressed growth of the tumor and yielded an additive therapeutic efficacy to gemcitabine and 5-FU. High expression of LAT1 is a promising pathological marker to predict the outcome in patients with biliary tract adenocarcinoma. Inhibition of LAT1 may be an effective targeted therapy for this distressing disease

  20. Transport of Amino Acids in Lactobacillus casei by Proton-Motive-Force-Dependent and Non-Proton-Motive-Force-Dependent Mechanisms

    NARCIS (Netherlands)

    Strobel, Herbert J.; Russell, James B.; Driessen, Arnold J.M.; Konings, Wilhelmus

    1989-01-01

    Lactobacilus casei 393 cells which were energized with glucose (pH 6.0) took up glutamine, asparagine, glutamate, aspartate, leucine, and phenylalanine. Little or no uptake of several essential amino acids (valine, isoleucine, arginine, cysteine, tyrosine, and tryptophan) was observed. Inhibition st

  1. D-amino acids trigger biofilm disassembly.

    Science.gov (United States)

    Kolodkin-Gal, Ilana; Romero, Diego; Cao, Shugeng; Clardy, Jon; Kolter, Roberto; Losick, Richard

    2010-04-30

    Bacteria form communities known as biofilms, which disassemble over time. In our studies outlined here, we found that, before biofilm disassembly, Bacillus subtilis produced a factor that prevented biofilm formation and could break down existing biofilms. The factor was shown to be a mixture of D-leucine, D-methionine, D-tyrosine, and D-tryptophan that could act at nanomolar concentrations. D-amino acid treatment caused the release of amyloid fibers that linked cells in the biofilm together. Mutants able to form biofilms in the presence of D-amino acids contained alterations in a protein (YqxM) required for the formation and anchoring of the fibers to the cell. D-amino acids also prevented biofilm formation by Staphylococcus aureus and Pseudomonas aeruginosa. D-amino acids are produced by many bacteria and, thus, may be a widespread signal for biofilm disassembly. PMID:20431016

  2. AMINO ACIDS APPLICATION TO CREATE OF NANOSTRUCTURES

    Directory of Open Access Journals (Sweden)

    I. S. Chekman

    2014-12-01

    Full Text Available Review is devoted to the amino acids that could be used for nanostructures creation. The investigation of corresponding properties of amino acids is essential for their role definition in creation of nanomedicines. However, amino acid studying as components of nanostructures is insufficient. Study of nanoparticles for medicines creation was initiated by the development of nanotechnology. Amino acids in complexes with the nanoparticles of organic and inorganic nature play an important role for medicines targeting in pathological process. They could reduce toxicity of the nanomaterials used in nanomedicine and are used for creation of biosensors, lab-on-chip and therefore they are a promising material for synthesis of new nanodrugs and diagnostic tools.

  3. Amino Acid Intake in Preterm Infants.

    Science.gov (United States)

    Burattini, Ilaria; Bellagamba, Maria Paola; D''Ascenzo, Rita; Biagetti, Chiara; Carnielli, Virgilio Paolo

    2016-01-01

    A large proportion of extremely low-birth-weight infants requires parenteral nutrition for variable lengths of time. Amino acids are the key ingredients of parenteral nutrition. The goal of appropriate amino acid administration is to promote anabolism and normal cellular development in order to limit the incidence of postnatal growth restriction, which is associated with neurodevelopmental delays. The benefits of early amino acid commencement soon after birth are compelling, especially on nitrogen balance, while long-term outcome studies are lacking. Amino acid administration at 2.5 g/kg per day has been shown to be superior to lower intakes; however, the benefits of intakes above 2.5 g/kg per day remain controversial. PMID:27336474

  4. Subcritical Water Extraction of Amino Acids from Atacama Desert Soils

    Science.gov (United States)

    Amashukeli, Xenia; Pelletier, Christine C.; Kirby, James P.; Grunthaner, Frank J.

    2007-01-01

    Amino acids are considered organic molecular indicators in the search for extant and extinct life in the Solar System. Extraction of these molecules from a particulate solid matrix, such as Martian regolith, will be critical to their in situ detection and analysis. The goals of this study were to optimize a laboratory amino acid extraction protocol by quantitatively measuring the yields of extracted amino acids as a function of liquid water temperature and sample extraction time and to compare the results to the standard HCl vapor- phase hydrolysis yields for the same soil samples. Soil samples from the Yungay region of the Atacama Desert ( Martian regolith analog) were collected during a field study in the summer of 2005. The amino acids ( alanine, aspartic acid, glutamic acid, glycine, serine, and valine) chosen for analysis were present in the samples at concentrations of 1 - 70 parts- per- billion. Subcritical water extraction efficiency was examined over the temperature range of 30 - 325 degrees C, at pressures of 17.2 or 20.0 MPa, and for water- sample contact equilibration times of 0 - 30 min. None of the amino acids were extracted in detectable amounts at 30 degrees C ( at 17.2 MPa), suggesting that amino acids are too strongly bound by the soil matrix to be extracted at such a low temperature. Between 150 degrees C and 250 degrees C ( at 17.2 MPa), the extraction efficiencies of glycine, alanine, and valine were observed to increase with increasing water temperature, consistent with higher solubility at higher temperatures, perhaps due to the decreasing dielectric constant of water. Amino acids were not detected in extracts collected at 325 degrees C ( at 20.0 MPa), probably due to amino acid decomposition at this temperature. The optimal subcritical water extraction conditions for these amino acids from Atacama Desert soils were achieved at 200 degrees C, 17.2 MPa, and a water- sample contact equilibration time of 10 min.

  5. Neutron inelastic scattering from amino acids

    International Nuclear Information System (INIS)

    Neutron incoherent inelastic scattering technique is used for studying the extensive hydrogen bonding that connects the molecules together and gives the structure cohesion in three dimension in amino acids. Results on five amino acids namely, α-glycine, DL-alanine, L-valine, L-tyrosine and L-phenyl-alanine having different side groups are reported and compared with those from other methods. The main emphasis is on the torsional motions of NH3+ and CH3 groups. (K.B.)

  6. Amino Acid Patterns around Disulfide Bonds

    Directory of Open Access Journals (Sweden)

    Brett Drury

    2010-11-01

    Full Text Available Disulfide bonds provide an inexhaustible source of information on molecular evolution and biological specificity. In this work, we described the amino acid composition around disulfide bonds in a set of disulfide-rich proteins using appropriate descriptors, based on ANOVA (for all twenty natural amino acids or classes of amino acids clustered according to their chemical similarities and Scheffé (for the disulfide-rich proteins superfamilies statistics. We found that weakly hydrophilic and aromatic amino acids are quite abundant in the regions around disulfide bonds, contrary to aliphatic and hydrophobic amino acids. The density distributions (as a function of the distance to the center of the disulfide bonds for all defined entities presented an overall unimodal behavior: the densities are null at short distances, have maxima at intermediate distances and decrease for long distances. In the end, the amino acid environment around the disulfide bonds was found to be different for different superfamilies, allowing the clustering of proteins in a biologically relevant way, suggesting that this type of chemical information might be used as a tool to assess the relationship between very divergent sets of disulfide-rich proteins.

  7. 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.

  8. Diurnal variation in insulin-stimulated systemic glucose and amino acid utilization in pigs fed with identical meals at 12-hour intervals

    NARCIS (Netherlands)

    Koopmans, S.J.; Meulen, van der J.; Dekker, R.A.; Corbijn, H.; Mroz, Z.

    2006-01-01

    The diurnal variation in insulin-stimulated systemic glucose and amino acid utilization was investigated in eleven pigs of similar to 40 kg. Pigs were fed isoenergetic/isoproteinic diets (366kj/kg BW0.75 per meal) in two daily rations (06:00 and 18:00h). After a 3-week habituation period, hyperinsul

  9. Aromatic amino acids in high selectivity bismuth(III) recognition.

    Science.gov (United States)

    Ghatak, Sumanta Kumar; Dey, Debarati; Sen, Souvik; Sen, Kamalika

    2013-04-21

    The three aromatic amino acids, tyrosine, tryptophan and phenylalanine, play different physiological roles in life processes. Metal ions capable of binding these amino acids may aid in the reduction of effective concentration of these amino acids in any physiological system. Here we have studied the efficacy of some heavy metals for their complexation with these three amino acids. Bismuth has been found to bind selectively with these aromatic amino acids and this was confirmed using spectrofluorimetric, spectrophotometric and cyclic voltammetric studies. The series of heavy metals has been chosen because each of these metals remains associated with the others at very low concentration levels and Bi(III) is the least toxic amongst the other elements. So, selective recognition for Bi(III) would also mean no response for the other heavy elements if contaminants are present even at low concentration levels. The affinity towards these amino acids has been found to be in the order tryptophan phenylalanine amino acids have been calculated using Benesi-Hildebrand equations and the corresponding free energy change has also been calculated. The values of the association constants obtained from BH equations using absorbance values corroborate with the Stern-Volmer constants obtained from fluorimetric studies. The evidence for complexation is also supported by the results of cyclic voltammetry.

  10. Hybrid gold single crystals incorporating amino acids

    CERN Document Server

    Chen, Linfeng; Weber, Eva; Fitch, Andy N; Pokroy, Boaz

    2016-01-01

    Composite hybrid gold crystals are of profound interest in various research areas ranging from materials science to biology. Their importance is due to their unique properties and potential implementation, for example in sensing or in bio-nanomedicine. Here we report on the formation of hybrid organic-metal composites via the incorporation of selected amino acids histidine, aspartic acid, serine, glutamine, alanine, cysteine, and selenocystine into the crystal lattice of single crystals of gold. We used electron microscopy, chemical analysis and high-resolution synchrotron powder X ray diffraction to examine these composites. Crystal shape, as well as atomic concentrations of occluded amino acids and their impact on the crystal structure of gold, were determined. Concentration of the incorporated amino acid was highest for cysteine, followed by serine and aspartic acid. Our results indicate that the incorporation process probably occurs through a complex interaction of their individual functional groups with ...

  11. Single amino acid supplementation in aminoacidopathies : a systematic review

    NARCIS (Netherlands)

    van Vliet, Danique; Derks, Terry G. J.; van Rijn, Margreet; de Groot, Martijn J.; MacDonald, Anita; Heiner-Fokkema, M. Rebecca; van Spronsen, Francjan J.

    2014-01-01

    Aminoacidopathies are a group of rare and diverse disorders, caused by the deficiency of an enzyme or transporter involved in amino acid metabolism. For most aminoacidopathies, dietary management is the mainstay of treatment. Such treatment includes severe natural protein restriction, combined with

  12. In silico analysis of amino acid biosynthesis and proteolysis in Lactobacillus delbrueckii subsp. bulgaricus 2038 and the implications for bovine milk fermentation.

    Science.gov (United States)

    Zheng, Huajun; Liu, Enuo; Hao, Pei; Konno, Tomonobu; Oda, Munehiro; Ji, Zai-Si

    2012-08-01

    The amino acid biosynthesis pathway and proteolytic system of Lactobacillus delbrueckii subsp. bulgaricus 2038 (L. bulgaricus 2038), a mainstay of large-scale yogurt production, were modeled based on its genomic sequence. L. bulgaricus 2038 retains more potential for amino acid synthesis and a more powerful proteolytic system than other L. bulgaricus strains, but favors amino acid uptake over de novo synthesis. Free amino acids and peptides in bovine milk provide the main nitrogen sources; whey is more important than casein for L. bulgaricus during fermentation. Free amino acids are imported by amino acid permeases and by ABC-type transport systems whereas exogenous oligopeptides are imported by ABC-type proteins only. Histidine is neither synthesized nor imported singly, which might explain why L. bulgaricus cannot grow in synthetic media.

  13. Exercise pre‑conditioning alleviates brain damage via excitatory amino acid transporter 2 and extracellular signal‑regulated kinase 1/2 following ischemic stroke in rats.

    Science.gov (United States)

    Wang, Xiao; Zhang, Min; Feng, Rui; Li, Wen-Bin; Ren, Shi-Qing; Zhang, Feng

    2015-02-01

    Previous studies have reported that physical exercise may exert a neuroprotective effect in humans as well as animals. However, the detailed mechanisms underlying the neuroprotective effect of exercise has remained to be elucidated. The aim of the present study was to explore the possible signaling pathways involved in the protective effect of pre‑ischemic treadmill training for ischemic stroke in rats. A total of 36 male Sprague‑Dawley rats were divided at random into three groups as follows (n=12 for each): Sham surgery group; middle cerebral artery occlusion (MCAO) group; and exercise with MCAO group. Following treadmill training for three weeks, the middle cerebral artery was occluded for 90 min in order to induce ischemic stroke, followed by reperfusion. Following 24 h post‑reperfusion, six rats from each group were assessed for neurological deficits and then sacrificed to calculate the infarct volume. The remaining rats (n=6 for each group) were sacrificed and the expression levels of excitatory amino acid transporter 2 (EAAT‑2) and extracellular signal‑regulated kinase 1/2 (ERK1/2) were detected using western blot analysis. The results of the present study demonstrated that rats that underwent pre‑ischemic exercise intervention had a significantly decreased brain infarct volume and neurological deficits; in addition, the pre‑ischemic exercise group showed decreased overexpression of phosphorylated ERK1/2 and increased expression of EAAT‑2 following ischemic stroke. In conclusion, treadmill training exercise prior to ischemic stroke alleviated brain damage in rats via regulation of EAAT‑2 and ERK1/2. PMID:25370789

  14. NRFL-1, the C. elegans NHERF orthologue, interacts with amino acid transporter 6 (AAT-6 for age-dependent maintenance of AAT-6 on the membrane.

    Directory of Open Access Journals (Sweden)

    Kohei Hagiwara

    Full Text Available The NHERF (Na(+/H(+ exchanger regulatory factor family has been proposed to play a key role in regulating transmembrane protein localization and retention at the plasma membrane. Due to the high homology between the family members, potential functional compensations have been a concern in sorting out the function of individual NHERF numbers. Here, we studied C. elegans NRFL-1 (C01F6.6 (nherf-like protein 1, the sole C. elegans orthologue of the NHERF family, which makes worm a model with low genetic redundancy of NHERF homologues. Integrating bioinformatic knowledge of C. elegans proteins into yeast two-hybrid scheme, we identified NRFL-1 as an interactor of AAT-6, a member of the C. elegans AAT (amino acid transporter family. A combination of GST pull-down assay, localization study, and co-immunoprecipitation confirmed the binding and characterized the PDZ interaction. AAT-6 localizes to the luminal membrane even in the absence of NRFL-1 when the worm is up to four-day old. A fluorescence recovery after photobleaching (FRAP analysis suggested that NRFL-1 immobilizes AAT-6 at the luminal membrane. When the nrfl-1 deficient worm is six-day or older, in contrast, the membranous localization of AAT-6 is not observed, whereas AAT-6 tightly localizes to the membrane in worms with NRFL-1. Sorting out the in vivo functions of the C. elegans NHERF protein, we found that NRFL-1, a PDZ-interactor of AAT-6, is responsible for the immobilization and the age-dependent maintenance of AAT-6 on the intestinal luminal membrane.

  15. The proton-coupled amino acid transporter hPAT1 is the main transporter involved in vigabatrin uptake in intestinal Caco-2 cells

    DEFF Research Database (Denmark)

    Nøhr, Martha Kampp; Hansen, Steen Honore'; Brodin, Birger;

    2012-01-01

    transporter hPAT1. The aim of the project was to identify if transporters are involved in cellular uptake of vigabatrin in Caco-2 cells. Methods: The uptake rate of vigabatrin was measured in Caco-2 cells at pH 6.0 or 7.4 for 15 min after application of 0.1 – 25.0 mM vigabatrin. The inhibitory effect...

  16. Escherichia coli, an Intestinal Microorganism, as a Biosensor for Quantification of Amino Acid Bioavailability

    Directory of Open Access Journals (Sweden)

    Vesela I. Chalova

    2009-09-01

    Full Text Available In animal diets optimal amino acid quantities and balance among amino acids is of great nutritional importance. Essential amino acid deficiencies have negative impacts on animal physiology, most often expressed in sub-optimal body weight gains. Over supplementation of diets with amino acids is costly and can increase the nitrogen emissions from animals. Although in vivo animal assays for quantification of amino acid bioavailability are well established, Escherichia coli-based bioassays are viable potential alternatives in terms of accuracy, cost, and time input. E. coli inhabits the gastrointestinal tract and although more abundant in colon, a relatively high titer of E. coli can also be isolated from the small intestine, where primary absorption of amino acids and peptides occur. After feed proteins are digested, liberated amino acids and small peptides are assimilated by both the small intestine and E. coli. The similar pattern of uptake is a necessary prerequisite to establish E. coli cells as accurate amino acid biosensors. In fact, amino acid transporters in both intestinal and E. coli cells are stereospecific, delivering only the respective biological L-forms. The presence of free amino- and carboxyl groups is critical for amino acid and dipeptide transport in both biological subjects. Di-, tri- and tetrapeptides can enter enterocytes; likewise only di-, tri- and tetrapeptides support E. coli growth. These similarities in addition to the well known bacterial genetics make E. coli an optimal bioassay microorganism for the assessment of nutritionally available amino acids in feeds.

  17. The role of nickel(II) on the homochirality of amino acids in living systems

    Institute of Scientific and Technical Information of China (English)

    Awni; Khatib; Fathi; Aqra

    2010-01-01

    The origin of homochirality in living organisms is controversial,stands out of being particularly important and a question which is still not satisfactorily answered.A mental picture of sequence of events that is thought to have preceded the existence of chirality in molecules is described.A chemical model to mimic the original abiotic conditions in an attempt to explain the preference of homochirality in living systems was tried.The effect which might have influenced this preference is presented.The sur...

  18. Review: Taurine: A “very essential” amino acid

    OpenAIRE

    Ripps, Harris; Shen, Wen

    2012-01-01

    Taurine is an organic osmolyte involved in cell volume regulation, and provides a substrate for the formation of bile salts. It plays a role in the modulation of intracellular free calcium concentration, and although it is one of the few amino acids not incorporated into proteins, taurine is one of the most abundant amino acids in the brain, retina, muscle tissue, and organs throughout the body. Taurine serves a wide variety of functions in the central nervous system, from development to cyto...

  19. FLU, an amino acid substitution model for influenza proteins

    OpenAIRE

    Gascuel Olivier; Le Quang; Dang Cuong; Le Vinh

    2010-01-01

    Abstract Background The amino acid substitution model is the core component of many protein analysis systems such as sequence similarity search, sequence alignment, and phylogenetic inference. Although several general amino acid substitution models have been estimated from large and diverse protein databases, they remain inappropriate for analyzing specific species, e.g., viruses. Emerging epidemics of influenza viruses raise the need for comprehensive studies of these dangerous viruses. We p...

  20. Branched-chain amino acid supplementation does not enhance athletic performance but affects muscle recovery and the immune system.

    Science.gov (United States)

    Negro, M; Giardina, S; Marzani, B; Marzatico, F

    2008-09-01

    Since the 1980's there has been high interest in branched-chain amino acids (BCAA) by sports nutrition scientists. The metabolism of BCAA is involved in some specific biochemical muscle processes and many studies have been carried out to understand whether sports performance can be enhanced by a BCAA supplementation. However, many of these researches have failed to confirm this hypothesis. Thus, in recent years investigators have changed their research target and focused on the effects of BCAA on the muscle protein matrix and the immune system. Data show that BCAA supplementation before and after exercise has beneficial effects for decreasing exercise-induced muscle damage and promoting muscle-protein synthesis. Muscle damage develops delayed onset muscle soreness: a syndrome that occurs 24-48 h after intensive physical activity that can inhibit athletic performance. Other recent works indicate that BCAA supplementation recovers peripheral blood mononuclear cell proliferation in response to mitogens after a long distance intense exercise, as well as plasma glutamine concentration. The BCAA also modifies the pattern of exercise-related cytokine production, leading to a diversion of the lymphocyte immune response towards a Th1 type. According to these findings, it is possible to consider the BCAA as a useful supplement for muscle recovery and immune regulation for sports events. PMID:18974721

  1. Amino acid survival in large cometary impacts

    Science.gov (United States)

    Pierazzo, E.; Chyba, C. F.

    1999-11-01

    A significant fraction of the Earth's prebiotic volatile inventory may have been delivered by asteroidal and cometary impacts during the period of heavy bombardment. The realization that comets are particularly rich in organic material seemed to strengthen this suggestion. Previous modeling studies, however, indicated that most organics would be entirely destroyed in large comet and asteroid impacts. The availability of new kinetic parameters for the thermal degradation of amino acids in the solid phase made it possible to readdress this question. We present the results of new high-resolution hydrocode simulations of asteroid and comet impact coupled with recent experimental data for amino acid pyrolysis in the solid phase. Differences due to impact velocity as well as projectile material have been investigated. Effects of angle of impacts were also addressed. The results suggest that some amino acids would survive the shock heating of large (kilometer-radius) cometary impacts. At the time of the origins of life on Earth, the steady-state oceanic concentration of certain amino acids (like aspartic and glutamic acid) delivered by comets could have equaled or substantially exceeded that due to Miller-Urey synthesis in a carbon dioxide-rich atmosphere. Furthermore, in the unlikely case of a grazing impact (impact angle around 5 degrees from the horizontal) an amount of some amino acids comparable to that due to the background steady-state production or delivery would be delivered to the early Earth.

  2. Method Development for Efficient Incorporation of Unnatural Amino Acids

    KAUST Repository

    Harris, Paul D.

    2014-04-01

    The synthesis of proteins bearing unnatural amino acids has the potential to enhance and elucidate many processes in biochemistry and molecular biology. There are two primary methods for site specific unnatural amino acid incorporation, both of which use the cell’s native protein translating machinery: in vitro chemical acylation of suppressor tRNAs and the use of orthogonal amino acyl tRNA synthetases. Total chemical synthesis is theoretically possible, but current methods severely limit the maximum size of the product protein. In vivo orthogonal synthetase methods suffer from the high cost of the unnatural amino acid. In this thesis I sought to address this limitation by increasing cell density, first in shake flasks and then in a bioreactor in order to increase the yield of protein per amount of unnatural amino acid used. In a parallel project, I used the in vitro chemical acylation system to incorporate several unnatural amino acids, key among them the fluorophore BODIPYFL, with the aim of producing site specifically fluorescently labeled protein for single molecule FRET studies. I demonstrated successful incorporation of these amino acids into the trial protein GFP, although incorporation was not demonstrated in the final target, FEN1. This also served to confirm the effectiveness of a new procedure developed for chemical acylation.

  3. In vivo unnatural amino acid expression in the methylotrophic yeast Pichia pastoris

    Science.gov (United States)

    Young, Travis [San Diego, CA; Schultz, Peter G [La Jolla, CA

    2014-02-11

    The invention provides orthogonal translation systems for the production of polypeptides comprising unnatural amino acids in methyltrophic yeast such as Pichia pastoris. Methods for producing polypeptides comprising unnatural amino acids in methyltrophic yeast such as Pichia pastoris are also provided.

  4. Modulation of phagosomal pH by Candida albicans promotes hyphal morphogenesis and requires Stp2p, a regulator of amino acid transport.

    OpenAIRE

    Slavena Vylkova; Lorenz, Michael C.

    2014-01-01

    Candida albicans, the most important fungal pathogen of humans, has a unique interaction with macrophages in which phagocytosis induces a switch from the yeast to hyphal form, allowing it to escape by rupturing the immune cell. While a variety of factors induce this switch in vitro, including neutral pH, it is not clear what triggers morphogenesis within the macrophage where the acidic environment should inhibit this transition. In vitro, C. albicans grown in similar conditions in which amino...

  5. Detection of non-protein amino acids in the presence of protein amino acids. II.

    Science.gov (United States)

    Shapshak, P.; Okaji, M.

    1972-01-01

    Studies conducted with the JEOL 5AH amino acid analyzer are described. This instrument makes possible the programming of the chromatographic process. Data are presented showing the separations of seventeen non-protein amino acids in the presence of eighteen protein amino acids. It is pointed out that distinct separations could be obtained in the case of a number of chemically similar compounds, such as ornithine and lysine, N-amidino alanine and arginine, and iminodiacetic acid and S-carboxymethyl cysteine and aspartic acid.

  6. In situ ore formation experiment: Amino acids and amino sugars trapped in artificial chimneys on deep-sea hydrothermal systems at Suiyo Seamount, Izu-Bonin Arc, Pacific Ocean

    CERN Document Server

    Takano,; Marumo,; K.,; Ebashi,; T.,; Gupta,; P., L; Kawahata,; H.,; Kobayashi,; K.,; Yamagishi,; A.,; Kuwabara,; T,

    2013-01-01

    The present study reports on the bio-organic composition of a deep-sea venting hydrothermal system originating from arc volcanism; the origin of the particulates in hydrothermal fluids from the Suiyo Seamount in the southern Izu-Bonin (Ogasawara) Arc is discussed with regard to amino compounds. Chimney samples on deep-sea hydrothermal systems and core samples at Suiyo Seamount were determined for amino acids, and occasionally amino sugars. Two types of chimney samples were obtained from active hydrothermal systems by submersible vehicles: one was natural chimney (NC) on a hydrothermal natural vent; the other was artificial chimneys (AC), mainly formed by the growth and deposition of sulfide-rich particulate components in a Kuwabara-type in situ incubator (KI incubator). Total hydrolyzed amino acids (THAA) and hydrolyzed hexosamines (HA) in AC ranged from 10.7 nmol/g to 64.0 nmol/g and from 0 nmol/g to 8.1 nmol/g, respectively, while THAA in hydrothermally altered core samples ranged from 26.0 nmol/g to 107.4 ...

  7. Production of carrier-peptide conjugates using chemically reactive unnatural amino acids

    Energy Technology Data Exchange (ETDEWEB)

    Young, Travis; Schultz, Peter G.

    2015-08-18

    Provided are methods of making carrier polypeptide that include incorporating a first unnatural amino acid into a carrier polypeptide variant, incorporating a second unnatural amino acid into a target polypeptide variant, and reacting the first and second unnatural amino acids to produce the conjugate. Conjugates produced using the provided methods are also provided. In addition, orthogonal translation systems in methylotrophic yeast and methods of using these systems to produce carrier and target polypeptide variants comprising unnatural amino acids are provided.

  8. Abc Amino Acids: Design, Synthesis, and Properties of New Photoelastic Amino Acids

    Energy Technology Data Exchange (ETDEWEB)

    Standaert, Robert F [ORNL; Park, Dr Seung Bum [Seoul National University

    2006-01-01

    Photoisomerizable amino acids provide a direct avenue to the experimental manipulation of bioactive polypeptides, potentially allowing real-time, remote control of biological systems and enabling useful applications in nanobiotechnology. Herein, we report a new class of photoisomerizable amino acids intended to cause pronounced expansion and contraction in the polypeptide backbone, i.e., to be photoelastic. These compounds, termed Abc amino acids, employ a photoisomerizable azobiphenyl chromophore to control the relative disposition of aminomethyl and carboxyl substituents. Molecular modeling of nine Abc isomers led to the identification of one with particularly attractive properties, including the ability to induce contractions up to 13A in the backbone upon transa?cis photoisomerization. This isomer, designated mpAbc, has substituents at meta and para positions on the inner (azo-linked) and outer rings, respectively. An efficient synthesis of Fmoc-protected mpAbc was executed in which the biaryl components were formed via Suzuki couplings and the azo linkage was formed via amine/nitroso condensation; protected forms of three other Abc isomers were prepared similarly. A decapeptide incorporating mpAbc was synthesized by conventional solid-phase methods and displayed characteristic azobenzene photochemical behavior with optimal conversion to the cis isomer at 360 nm and a thermal cisa?trans half life of 100 min. at 80 AoC.

  9. Amino acid "little Big Bang": Representing amino acid substitution matrices as dot products of Euclidian vectors

    Directory of Open Access Journals (Sweden)

    Zimmermann Karel

    2010-01-01

    Full Text Available Abstract Background Sequence comparisons make use of a one-letter representation for amino acids, the necessary quantitative information being supplied by the substitution matrices. This paper deals with the problem of finding a representation that provides a comprehensive description of amino acid intrinsic properties consistent with the substitution matrices. Results We present a Euclidian vector representation of the amino acids, obtained by the singular value decomposition of the substitution matrices. The substitution matrix entries correspond to the dot product of amino acid vectors. We apply this vector encoding to the study of the relative importance of various amino acid physicochemical properties upon the substitution matrices. We also characterize and compare the PAM and BLOSUM series substitution matrices. Conclusions This vector encoding introduces a Euclidian metric in the amino acid space, consistent with substitution matrices. Such a numerical description of the amino acid is useful when intrinsic properties of amino acids are necessary, for instance, building sequence profiles or finding consensus sequences, using machine learning algorithms such as Support Vector Machine and Neural Networks algorithms.

  10. Amino acids in the sedimentary humic and fulvic acids

    Digital Repository Service at National Institute of Oceanography (India)

    Sardessai, S.

    Humic and fulvic acids isolated from a few sediment samples from Arabian Sea and Bay of Bengal were analysed for total hydrolysable amino acids concentration and their composition. The amono acids content of fulvic acids was higher than in the humic...

  11. Modulation of phagosomal pH by Candida albicans promotes hyphal morphogenesis and requires Stp2p, a regulator of amino acid transport.

    Science.gov (United States)

    Vylkova, Slavena; Lorenz, Michael C

    2014-03-01

    Candida albicans, the most important fungal pathogen of humans, has a unique interaction with macrophages in which phagocytosis induces a switch from the yeast to hyphal form, allowing it to escape by rupturing the immune cell. While a variety of factors induce this switch in vitro, including neutral pH, it is not clear what triggers morphogenesis within the macrophage where the acidic environment should inhibit this transition. In vitro, C. albicans grown in similar conditions in which amino acids are the primary carbon source generate large quantities of ammonia to raise the extracellular pH and induce the hyphal switch. We show here that C. albicans cells neutralize the macrophage phagosome and that neutral pH is a key inducer of germination in phagocytosed cells by using a mutant lacking STP2, a transcription factor that regulates the expression of multiple amino acid permeases, that is completely deficient in alkalinization in vitro. Phagocytosed stp2Δ mutant cells showed significant reduction in hypha formation and escaped from macrophages less readily compared to wild type cells; as a result stp2Δ mutant cells were killed at a higher rate and caused less damage to RAW264.7 macrophages. Stp2p-regulated import leads to alkalinization of the phagosome, since the majority of the wild type cells fail to co-localize with acidophilic dyes, whereas the stp2Δ mutant cells were located in acidic phagosomes. Furthermore, stp2Δ mutant cells were able to form hyphae and escape from neutral phagosomes, indicating that the survival defect in these cells was pH dependent. Finally, these defects are reflected in an attenuation of virulence in a mouse model of disseminated candidiasis. Altogether our results suggest that C. albicans utilizes amino acids to promote neutralization of the phagosomal pH, hyphal morphogenesis, and escape from macrophages. PMID:24626429

  12. Modulation of phagosomal pH by Candida albicans promotes hyphal morphogenesis and requires Stp2p, a regulator of amino acid transport.

    Directory of Open Access Journals (Sweden)

    Slavena Vylkova

    2014-03-01

    Full Text Available Candida albicans, the most important fungal pathogen of humans, has a unique interaction with macrophages in which phagocytosis induces a switch from the yeast to hyphal form, allowing it to escape by rupturing the immune cell. While a variety of factors induce this switch in vitro, including neutral pH, it is not clear what triggers morphogenesis within the macrophage where the acidic environment should inhibit this transition. In vitro, C. albicans grown in similar conditions in which amino acids are the primary carbon source generate large quantities of ammonia to raise the extracellular pH and induce the hyphal switch. We show here that C. albicans cells neutralize the macrophage phagosome and that neutral pH is a key inducer of germination in phagocytosed cells by using a mutant lacking STP2, a transcription factor that regulates the expression of multiple amino acid permeases, that is completely deficient in alkalinization in vitro. Phagocytosed stp2Δ mutant cells showed significant reduction in hypha formation and escaped from macrophages less readily compared to wild type cells; as a result stp2Δ mutant cells were killed at a higher rate and caused less damage to RAW264.7 macrophages. Stp2p-regulated import leads to alkalinization of the phagosome, since the majority of the wild type cells fail to co-localize with acidophilic dyes, whereas the stp2Δ mutant cells were located in acidic phagosomes. Furthermore, stp2Δ mutant cells were able to form hyphae and escape from neutral phagosomes, indicating that the survival defect in these cells was pH dependent. Finally, these defects are reflected in an attenuation of virulence in a mouse model of disseminated candidiasis. Altogether our results suggest that C. albicans utilizes amino acids to promote neutralization of the phagosomal pH, hyphal morphogenesis, and escape from macrophages.

  13. Asymmetric transcriptomic signatures between the cob and florets in the maize ear under optimal- and low-nitrogen conditions at silking, and functional characterization of amino acid transporters ZmAAP4 and ZmVAAT3.

    Science.gov (United States)

    Pan, Xiaoying; Hasan, Md Mahmudul; Li, Yanqiang; Liao, Chengsong; Zheng, Hongyan; Liu, Renyi; Li, Xuexian

    2015-10-01

    Coordinated functioning of the cob and florets of the maize ear confers grain yield. The cob is critical for carbon partitioning and assimilated nitrogen (N) supply for grain development. However, molecular recognition of the cob and peripheral florets, characterization of genes mediating translocation of N assimilates, and responses of these two tissues to low N (LN) remain elusive. Transcriptional profiling of the ear of a maize hybrid at silking in the field revealed 1864 differentially expressed genes between the cob and florets, with 1314 genes up-regulated in the cob and 550 genes up-regulated in florets. The cob was characterized by striking enrichment of genes that are involved in carbon/N transport and metabolism, consistent with the physiological role of the cob in carbon/N storage and transfer during ear development. The florets were characterized by enrichment of hormone signalling components and development related genes. We next examined the response of the cob and florets to LN stress. LN caused differential expression of 588 genes in the cob and only 195 genes in the florets, indicating that the cob dominated the response of the ear to LN at the transcriptional level. LN caused comprehensive alterations such as carbon/N metabolism or partitioning, hormone signalling and protein phosphorylation in terms of gene expression in the cob and/or florets. Fourteen genes responsive specifically to LN provided potential molecular markers for N-efficient maize breeding. We further functionally characterized two newly identified broad-spectrum amino acid transporters, ZmAAP4 and ZmVAAT3, that showed distinct expression patterns in the cob and florets and potentially important roles in amino-N mobilization in the ear. While both proteins could transport various amino acids into yeast or Arabidopsis cells, ZmAAP4 appeared to have higher efficiencies than ZmVAAT3 in transporting seven out of 22 examined amino acids. PMID:26136266

  14. D-Serine metabolism in C6 glioma cells: Involvement of alanine-serine-cysteine transporter (ASCT2) and serine racemase (SRR) but not D-amino acid oxidase (DAO)

    OpenAIRE

    Sikka, Pilleriin; Walker, Rosie; Cockayne, Rebecca; Wood, Matthew JA; Harrison, Paul J; Burnet, Philip WJ

    2010-01-01

    D-serine is an endogenous N-methyl-D-aspartate (NMDA) receptor coagonist. It is synthesized from L-serine by serine racemase (SRR), but many aspects of its metabolism remain unclear, especially in the forebrain, which lacks active D-amino acid oxidase (DAO), the major D-serine degradative enzyme. Candidate mechanisms include SRR operating in α,β-eliminase mode (converting D-serine to pyruvate) and regulation by serine transport, in which the alanine-serine-cysteine transporter ASCT2 is implic...

  15. Energetics of Amino Acid Synthesis in Alkaline Hydrothermal Environments

    Science.gov (United States)

    Kitadai, Norio

    2015-12-01

    Alkaline hydrothermal systems have received considerable attention as candidates for the origin and evolution of life on the primitive Earth. Nevertheless, sufficient information has not yet been obtained for the thermodynamic properties of amino acids, which are necessary components for life, at high temperatures and alkaline pH. These properties were estimated using experimental high-temperature volume and heat capacity data reported in the literature for several amino acids, together with correlation algorithms and the revised Helgeson-Kirkham-Flowers (HKF) equations of state. This approach enabled determination of a complete set of the standard molal thermodynamic data and the revised HKF parameters for the 20 protein amino acids in their zwitterionic and ionization states. The obtained dataset was then used to evaluate the energetics of amino acid syntheses from simple inorganic precursors (CO2, H2, NH3 and H2S) in a simulated alkaline hydrothermal system on the Hadean Earth. Results show that mixing between CO2-rich seawater and the H2-rich hydrothermal fluid can produce energetically favorable conditions for amino acid syntheses, particularly in the lower-temperature region of such systems. Together with data related to the pH and temperature dependences of the energetics of amino acid polymerizations presented in earlier reports, these results suggest the following. Hadean alkaline hydrothermal settings, where steep pH and temperature gradients may have existed between cool, slightly acidic Hadean ocean water and hot, alkaline hydrothermal fluids at the vent-ocean interface, may be energetically the most suitable environment for the synthesis and polymerization of amino acids.

  16. {sup 123}I-BPA and {sup 123}I-BPA-fructose complex as a new radiopharmaceutical for the imaging of amino acid transport in tumor

    Energy Technology Data Exchange (ETDEWEB)

    Choi, T. H.; Choi, C. W.; Woo, K. S.; Chung, W. S.; Lim, S. J.; Lee, S. J.; Hong, S. W.; Lim, S. M. [Korea Cancer Center, Seoul (Korea, Republic of)

    1999-07-01

    Boronophenylalanine (BPA) as derivative of phenylalanine, was used to treatment for glioma and melanoma in BNCT. We labeled BPA with radioiodides for tumor imaging of amino acid transport with gamma camera. Because of limited solubility of BAP, I-BPA-Fructose(I-BPA was complexed with fructose) to increase solubility. I-BPA was labeled by chloramine T coated bead method. Serum stability of I-BPA analyzed by HPLC at 37 .deg. C. Cellular uptake of I-BPA and I-BPA-Fructose was compared in 9L glioma and B16 melanoma. To see biodistribution, I-BPA 9x10{sup 5}Bq(20 {mu}g/100 {mu}l) or I-BPA-Fructose 9x10{sup 5}Bq(20 {mu}g/fructose 55 {mu}g/100 {mu}l) was injected to B16 melanoma bearing C57 mice. In tumor bearing mice at 30 min, 1, 2, 24 hr after injection of tracers (n-4 per group). In 24hr, radiochemical purity of I-BPA in serum was retained above 90%. In cultured cells the maximum uptake was observed at 60min. In 9L glioma cells, %uptake of I-BPA and I-BPA-Fructose was 2.05, 2.6 at 60min. But in B16 melanoma, %uptake of I-BPA and I-BPA and-Fructose was 2.57, 6.62 at 60 min. In melanoma bearing mice, tumor/muscle ratio of I-BPA in 30 min, 1hr, 2hr, 24hr after injection was 1.48, 2.19, 2.28, 0.29 and %ID/g of tumor was 6.25, 5.17, 3.52, 0.29. Tumor/muscle ratio of I-BPA-Fructose was 1.51, 2.05, 2.1, 2.84 in 30 min, 1hr, 2hr, 24hr post-injection and %ID/g of tumor was 4.61, 3.65, 2.93, 0.71. The radioactivity was excreted mainly via hepatobiliary tract to the intestine. I-BPA was stable in serum upto 24hr. Uptake of I-BPA-Fructose was higher than I-BPA in melanoma cells. I-BPA-Fructose, is a promising tumor imaging radiopharmaceutical in some tumors.

  17. Amino acid derived 1,4-dialkyl substituted imidazolones

    DEFF Research Database (Denmark)

    Diness, Frederik; Meldal, Morten Peter

    2010-01-01

    A general method for synthesis of 1,4-substituted imidazolones from amino acids on solid support or in solution has been developed. Amino acid derived 3-Boc-(1,3)-oxazinane (Box) protected amino aldehyde building blocks were coupled through urea bonds to the amino terminal of dipeptides or amino ...

  18. D-Serine Is a Substrate for Neutral Amino Acid Transporters ASCT1/SLC1A4 and ASCT2/SLC1A5, and Is Transported by Both Subtypes in Rat Hippocampal Astrocyte Cultures.

    Directory of Open Access Journals (Sweden)

    Alan C Foster

    Full Text Available N-methyl-D-aspartate (NMDA receptors play critical roles in synaptic transmission and plasticity. Activation of NMDA receptors by synaptically released L-glutamate also requires occupancy of co-agonist binding sites in the tetrameric receptor by either glycine or D-serine. Although D-serine appears to be the predominant co-agonist at synaptic NMDA receptors, the transport mechanisms involved in D-serine homeostasis in brain are poorly understood. In this work we show that the SLC1 amino acid transporter family members SLC1A4 (ASCT1 and SLC1A5 (ASCT2 mediate homo- and hetero-exchange of D-serine with physiologically relevant kinetic parameters. In addition, the selectivity profile of D-serine uptake in cultured rat hippocampal astrocytes is consistent with uptake mediated by both ASCT1 and ASCT2. Together these data suggest that SLC1A4 (ASCT1 may represent an important route of Na-dependent D-serine flux in the brain that has the ability to regulate extracellular D-serine and thereby NMDA receptor activity.

  19. Large neutral amino acids in daily practice

    DEFF Research Database (Denmark)

    Ahring, Kirsten Kiær

    2010-01-01

    sampling to measure plasma amino acid (AA) concentrations. The aim of this analysis and treatment is that the patient receives 25-30% of the daily protein requirement from LNAA supplementation and the remaining 70-75% from natural, low-phenylalanine proteins (although some patients have difficulties...

  20. Dietary Supplements and Sports Performance: Amino Acids

    OpenAIRE

    Williams Melvin

    2005-01-01

    Abstract This is the third in a series of six articles to discuss the major classes of dietary supplements (vitamins; minerals; amino acids; herbs or botanicals; metabolites, constituents/extracts, or combinations). The major focus is on efficacy of such dietary supplements to enhance exercise or sport performance.

  1. Dietary Supplements and Sports Performance: Amino Acids

    Directory of Open Access Journals (Sweden)

    Williams Melvin

    2005-12-01

    Full Text Available Abstract This is the third in a series of six articles to discuss the major classes of dietary supplements (vitamins; minerals; amino acids; herbs or botanicals; metabolites, constituents/extracts, or combinations. The major focus is on efficacy of such dietary supplements to enhance exercise or sport performance.

  2. Estimate of Amino Acid Balance in Nutrition

    Institute of Scientific and Technical Information of China (English)

    SunWenzhi

    1995-01-01

    A new chemical index-imbalance degree(IBD),was proposed on the basis of cluster analysis in multivariate statistical analysis to estimate the extent of amino acid balance in protein.The range of IBD is between 0 and 1,successively corresponding to complete baance and entire imbalance for the amino acid profile of a sample.The amino acid increment model of IBD belongs to an asymmetrical maximum-type,and there is a high correlation between IBD and coefficient of variation(CV),The nutritional Value of individual feed can be ranked and clustered according to its IBD;and by calculating the IBD of amixed sample with two or more feedstuffs,it is possible theoretically to predict whether a synergetic phenomenon exists and when an optimal mutual complement can happen.If the conceptive frame of IBD extended,it can be used to study the balance of plement can happen.If the conceptive frame of IBD extended,it can be used to study the balance of nutrients besides amino acids,and is helpful to realize the automatic distinction and selection in diet formulating.

  3. Amino acid modifications on tRNA

    Institute of Scientific and Technical Information of China (English)

    Jing Yuan; Kelly Sheppard; Dieter S(o)ll

    2008-01-01

    The accurate formation of cognate aminoacyl-transfer RNAs (aa-tRNAs) is essential for the fidelity of translation.Most amino acids are esterified onto their cognate tRNA isoacceptors directly by aa.tRNA synthetases.However,in the case of four amino acids (Gin,Asn,Cys and Sec),aminoacyl-tRNAs are made through indirect pathways in many organisms across all three domains of life.The process begins with the charging ofnoncognate amino acids to tRNAs by a specialized synthetase in the case of Cys-tRNAcys formation or by synthetases with relaxed specificity,such as the non-discriminating glutamyl-tRNA,non-discriminating aspartyl-tRNA and seryl-tRNA synthetases.The resulting misacylated tRNAs are then converted to cognate pairs through transformation of the amino acids on the tRNA,which is catalyzed by a group of tRNA-dependent modifying enzymes,such as tRNA-dependent amidotransferases,Sep-tRNA:Cys-tRNA synthase,O-phosphoseryi-tRNA kinase and Sep-tRNA:Sec-tRNA synthase.The majority of these indirect pathways are widely spread in all domains of life and thought to be part of the evolutionary process.

  4. Role of mitochondrial transamination in branched chain amino acid metabolism

    Energy Technology Data Exchange (ETDEWEB)

    Hutson, S.M.; Fenstermacher, D.; Mahar, C.

    1988-03-15

    Oxidative decarboxylation and transamination of 1-/sup 14/C-branched chain amino and alpha-keto acids were examined in mitochondria isolated from rat heart. Transamination was inhibited by aminooxyacetate, but not by L-cycloserine. At equimolar concentrations of alpha-ketoiso(1-/sup 14/C)valerate (KIV) and isoleucine, transamination was increased by disrupting the mitochondria with detergent which suggests transport may be one factor affecting the rate of transamination. Next, the subcellular distribution of the aminotransferase(s) was determined. Branched chain aminotransferase activity was measured using two concentrations of isoleucine as amino donor and (1-/sup 14/C)KIV as amino acceptor. The data show that branched chain aminotransferase activity is located exclusively in the mitochondria in rat heart. Metabolism of extramitochondrial branched chain alpha-keto acids was examined using 20 microM (1-/sup 14/C)KIV and alpha-ketoiso(1-/sup 14/C)caproate (KIC). There was rapid uptake and oxidation of labeled branched chain alpha-keto acid, and, regardless of the experimental condition, greater than 90% of the labeled keto acid substrate was metabolized during the 20-min incubation. When a branched chain amino acid (200 microM) or glutamate (5 mM) was present, 30-40% of the labeled keto acid was transaminated while the remainder was oxidized. Provision of an alternate amino acceptor in the form of alpha-keto-glutarate (0.5 mM) decreased transamination of the labeled KIV or KIC and increased oxidation. Metabolism of intramitochondrially generated branched chain alpha-keto acids was studied using (1-/sup 14/C)leucine and (1-/sup 14/C)valine. Essentially all of the labeled branched chain alpha-keto acid produced by transamination of (1-/sup 14/C)leucine or (1-/sup 14/C)valine with a low concentration of unlabeled branched chain alpha-keto acid (20 microM) was oxidized.

  5. Using the cre-lox recombination system to assess functional impairment caused by amino acid substitutions in yeast proteins

    Directory of Open Access Journals (Sweden)

    Shirley Renee L.

    2004-01-01

    Full Text Available A method was developed to assess the functional significance of a sequence motif in yeast Upf3p, a protein required for nonsense-mediated mRNA decay (NMD. The motif lies at the edge of the Upf3p-Upf2p interaction domain, but at the same time resembles the canonical leucine-rich nuclear export sequence (NES found in proteins that bind Crm1p exportin. To test the function of the putative NES, site-directed mutations that cause substitutions of conserved NES-A residues were first selected to identify hypermorphic alleles. Next, a portable Crm1p-binding NES from HIV-1 Rev protein that functions in yeast was fused en masse to the C-terminus of variant Upf3 proteins using loxP sites recognized by bacterial cre-recombinase. Finally, variant Upf3-Rev proteins that were functional in NMD were selected and examined for the types of amino acid substitutions present in NES-A. The mutational analysis revealed that amino acid substitutions in the Upf3 NES impair both nuclear export and the Upf2p-Upf3p interaction, both of which are required for Upf3p to function in NMD. The method described in this report could be modified for the genetic analysis of a variety of portable protein domains.

  6. [Effect of proteolysis inhibitors on the incorporation of labelled amino acids into proteins].

    Science.gov (United States)

    Konikova, A S; Korotkina, R N

    1975-01-01

    Role of peptide bond breaks in the incorporation of amino acids into proteins in a "protein--amino acid" system is investigated. For this purpose the incorporation of labelled amino acids into trypsin under the inhibition of its autolysis by a specific inhibitor from soybean and epsilon-amino-caproic acid is studied. The trypsin inhibitor from soybean is found to suppress considerably the incorporation of 14C-glycine, 14C-lysine and 14C-methionine into crystal trypsin and not to affect the incorporation of labelled amino acids into chomotrypsin, papain and carboxypeptidase. Epsilon-Aminocaproic acid inhibited 14C-glycine incorporation into crystal trypsin by 40% and did not change its incorporation level into serum albumin. The dependency of amino acid incorporation level into trypsin on the activity of autolysis in the "protein--amino acid" system is demonstrated. PMID:1212456

  7. FLU, an amino acid substitution model for influenza proteins

    Directory of Open Access Journals (Sweden)

    Gascuel Olivier

    2010-04-01

    Full Text Available Abstract Background The amino acid substitution model is the core component of many protein analysis systems such as sequence similarity search, sequence alignment, and phylogenetic inference. Although several general amino acid substitution models have been estimated from large and diverse protein databases, they remain inappropriate for analyzing specific species, e.g., viruses. Emerging epidemics of influenza viruses raise the need for comprehensive studies of these dangerous viruses. We propose an influenza-specific amino acid substitution model to enhance the understanding of the evolution of influenza viruses. Results A maximum likelihood approach was applied to estimate an amino acid substitution model (FLU from ~113, 000 influenza protein sequences, consisting of ~20 million residues. FLU outperforms 14 widely used models in constructing maximum likelihood phylogenetic trees for the majority of influenza protein alignments. On average, FLU gains ~42 log likelihood points with an alignment of 300 sites. Moreover, topologies of trees constructed using FLU and other models are frequently different. FLU does indeed have an impact on likelihood improvement as well as tree topologies. It was implemented in PhyML and can be downloaded from ftp://ftp.sanger.ac.uk/pub/1000genomes/lsq/FLU or included in PhyML 3.0 server at http://www.atgc-montpellier.fr/phyml/. Conclusions FLU should be useful for any influenza protein analysis system which requires an accurate description of amino acid substitutions.

  8. An Experimental Styudy on Gold Solubility in Amino Acid Solution and Its Geological Significance

    Institute of Scientific and Technical Information of China (English)

    张景荣; 陆建军; 等

    1996-01-01

    The experiments on gold solubility in amino acid solution mdicate that gold is very intensively soluble in amino acid(or other organic acids),which is extensively present in geological bodies,and is most soluble in histidine.The temperature and concentration,acidity and type of amino acid in the solution are important factors affecting gold-amino acid complexing. The solubility of gold in amino acid is different under different conditions of temperature, amino acid concentration and pH value of the solution,At 80℃ and pH=6-8,gold is most soluble in amino acid.Gold dispersed in water and rocks could be concentrated and transported by amino acid and then precipitated in favorable loci.Amino acids might have played an important role in metallogenesis as well as in the formation of source beds of gold.Nitrogen,oxygen and sulfur in amino acid might have reacted with gold to form soluble complex ions.

  9. Amino acid-responsive Crohn's disease: a case study

    Directory of Open Access Journals (Sweden)

    Alvin Stein

    2010-12-01

    Full Text Available Alvin Stein1, Marty Hinz2, Thomas Uncini31Stein Orthopedic Associates, Plantation, FL, USA; 2Clinical Research, NeuroResearch Clinics Inc., Cape Coral, FL, USA; 3Laboratory, Fairview Regional Medical Center-Mesabi, Hibbing, MN, USAPurpose: This paper reviews the clinical course of a case of severe Crohn's disease and discusses the scientific ramifications of a novel treatment approach.Patients and methods: A case study of a 37-year-old male with a 22-year history of Crohn's disease whose clinical course had experienced no sustained remissions. The patient was treated with a protocol that utilized serotonin and dopamine amino acid precursors administered under the guidance of organic cation transporter assay interpretation.Results: Within 5 days of achieving the necessary balance of serotonin and dopamine, the patient experienced remission of symptoms. This remission has been sustained without the use of any Crohn's disease medications.Conclusion: In Crohn's disease, it is known that there is an increase of both synthesis and tissue levels of serotonin in specific locations. It is asserted that this is prima facie evidence of a significant imbalance in the serotonin–dopamine system, leading to serotonin toxicity. The hypothesis formulated is that improperly balanced serotonin and dopamine transport, synthesis, and metabolism is a primary defect contributing to the pathogenesis of Crohn's disease.Keywords: serotonin, dopamine, organic cation transporters, OCT

  10. Nature's starships. I. Observed abundances and relative frequencies of amino acids in meteorites

    Energy Technology Data Exchange (ETDEWEB)

    Cobb, Alyssa K.; Pudritz, Ralph E., E-mail: cobbak@mcmaster.ca, E-mail: pudritz@physics.mcmaster.ca [Origins Institute, McMaster University, ABB 241, 1280 Main Street, Hamilton, ON L8S 4M1 (Canada)

    2014-03-10

    The class of meteorites called carbonaceous chondrites are examples of material from the solar system which have been relatively unchanged from the time of their initial formation. These meteorites have been classified according to the temperatures and physical conditions of their parent planetesimals. We collate available data on amino acid abundance in these meteorites and plot the concentrations of different amino acids for each meteorite within various meteorite subclasses. We plot average concentrations for various amino acids across meteorites separated by subclass and petrologic type. We see a predominance in the abundance and variety of amino acids in CM2 and CR2 meteorites. The range in temperature corresponding to these subclasses indicates high degrees of aqueous alteration, suggesting aqueous synthesis of amino acids. Within the CM2 and CR2 subclasses, we identify trends in relative frequencies of amino acids to investigate how common amino acids are as a function of their chemical complexity. These two trends (total abundance and relative frequencies) can be used to constrain formation parameters of amino acids within planetesimals. Our organization of the data supports an onion shell model for the temperature structure of planetesimals. The least altered meteorites (type 3) and their amino acids originated near cooler surface regions. The most active amino acid synthesis likely took place at intermediate depths (type 2). The most altered materials (type 1) originated furthest toward parent body cores. This region is likely too hot to either favor amino acid synthesis or for amino acids to be retained after synthesis.

  11. Quantitative determination of amino acids in earthworm meal (Eisenia andrei) by a Surveyor HPLC system in conjunction with pre-column 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate derivatization

    OpenAIRE

    Ovalles-Dur??n, J.F.; Medina, A.; M??rquez, Elil; Rochette, Julie; Morillo, Marielba; Luna, Jos?? Rafael

    2014-01-01

    Aim: The objective of this study was to evaluate the integration of the AccQ???Tag derivatization system with the Finnigan Surveyor Plus HPLC system to determine the amino acids (aa) composition of earthworm meal protein post-hydrolysis. Materials and Methods: In lab cultivated earthworms (Eisenia andrei) were reduced to flour which was then hydrolyzed with 6M HCl at 110 ??C for 24 hours in a closed system. The hydrolysis product was neutralized and their aa were derivatized with 6-aminoqu...

  12. Kinetic estimation of hydrogen isotope exchange reaction between tritiated-water (HTO) vapor and each amino acid in a heterogeneous system

    International Nuclear Information System (INIS)

    The hydrogen isotope exchange reaction between HTO vapor and each amino acid has been observed in order to establish a method of estimation of the internal exposure of organically bound tritium in a heterogeneous system at 25-70degC. Rate constants (k) for the amino acids have been obtained by applying the A''-McKay plot method. Using these k values, Arrhenius plots for both the COOH and NH2 groups are drawn, and linearity was obtained over the range of 25-70degC. Comparing the rate constants, the following four statements can be made regarding the T-for-H exchange reaction. (1) The reactivity of the functional groups in amino acids increases with increasing temperature. (2) Applying Taft's equation, the ratio of polar effect to steric effect is 2:8 in the COOH group and 9:1 in the NH2 group at 25degC. (3) The A''-McKay plot method is useful for studying the reactivity of materials, not only with one (or the same kind of) functional group(s) but also with two different kinds of functional groups. (4) The method used in this work may be useful to investigate the behavior of organically bound tritium, quantitatively. (author)

  13. Intermolecular Vibrations of Hydrophobic Amino Acids

    Science.gov (United States)

    Williams, Michael Roy Casselman

    Hydrophobic amino acids interact with their chemical environment through a combination of electrostatic, hydrogen bonding, dipole, induced dipole, and dispersion forces. These interactions all have their own characteristic energy scale and distance dependence. The low-frequency (0.1-5 THz, 5-150 cm-1) vibrational modes of amino acids in the solid state are a direct indicator of the interactions between the molecules, which include interactions between an amino acid functional group and its surroundings. This information is central to understanding the dynamics and morphology of proteins. The alpha-carbon is a chiral center for all of the hydrophobic amino acids, meaning that they exist in two forms, traditionally referred to as L- and D-enantiomers. This nomenclature indicates which direction the molecule rotates plane-polarized visible light (levorotory and dextrorotory). Chiral a-amino acids in proteins are exclusively the L-variety In the solid state, the crystal lattice of the pure L-enantiomer is the mirror image of the D-enantiomer crystal lattice. These solids are energetically identical. Enantiomers also have identical spectroscopic properties except when the measurement is polarization sensitive. A mixture of equal amounts D- and L-amino acid enantiomers can crystallize into a racemic (DL-) structure that is different from that of the pure enantiomers. Whether a solution of both enantiomers will crystallize into a racemic form or spontaneously resolve into a mixture of separate D- and L-crystals largely depends on the interactions between molecules available in the various possible configurations. This is an active area of research. Low-frequency vibrations with intermolecular character are very sensitive to changes in lattice geometry, and consequently the vibrational spectra of racemic crystals are usually quite distinct from the spectra of the crystals of the corresponding pure enantiomers in the far-infrared (far-IR). THz time-domain spectroscopy (THz

  14. Solid state radiolysis of amino acids in an astrochemical perspective

    Energy Technology Data Exchange (ETDEWEB)

    Cataldo, Franco, E-mail: franco.cataldo@fastwebnet.i [Istituto Nazionale di Astrofisica-Osservatorio Astrofisica di Catania, Via S. Sofia 78, 95123 Catania (Italy); Lupi Chemical Research, Via Casilina 1626/A, 00133 Rome (Italy); Angelini, Giancarlo [Istituto di Metodologie Chimiche, CNR, Via Salaria Km 29300, 00016 Monterotondo Stazione, Rome (Italy); Iglesias-Groth, Susana [Instituto de Astrofisica de Canarias, Via Lactea s/n, E-38200, La Laguna, Tenerife (Spain); Manchado, Arturo [Instituto de Astrofisica de Canarias, Via Lactea s/n, E-38200, La Laguna, Tenerife (Spain) and CSIC (Spain)

    2011-01-15

    The aliphatic amino acids L-alanine and L-leucine and the aromatic amino acids L-phenylalanine, L-tyrosine and L-tryptophan were irradiated in the solid state to a dose of 3.2 MGy. The degree of decomposition was measured by differential scanning calorimetry (DSC). Furthermore the degree of radioracemization was measured by optical rotatory dispersion (ORD) spectroscopy. From the DSC measurement a radiolysis rate constant k and the half life T{sub 1/2} for each amino acid have been determined and extrapolated to a dose of 14 MGy, which corresponds to the expected total dose delivered by the decay of radionuclides to the organic molecules present in comets and asteroids in 4.6x10{sup 9} years, the age of the Solar System. It is shown that all the amino acids studied can survive a radiation dose of 14 MGy although they are reduced to 1/4-1/5 of their original value they had at the beginning of the history of the Solar System. Consequently, the amount of alanine or leucine found today in the meteorites known as carbonaceous chondrites is just 1/4-1/5 of the amount originally present at the epoch of the formation of the Solar System 4.6x10{sup 9} years ago. Among the amino acids studied, tyrosine shows the highest radiation resistance while tryptophan does not combine its relatively high radiation resistance with an elevated level of radioracemization resistance. Apart from the exception of tryptophan, it is shown that the radiolysis rate constants k of all the amino acids studied are in reasonable agreement with the radioracemization rate constant k{sub rac}.

  15. Solid state radiolysis of amino acids in an astrochemical perspective

    Science.gov (United States)

    Cataldo, Franco; Angelini, Giancarlo; Iglesias-Groth, Susana; Manchado, Arturo

    2011-01-01

    The aliphatic amino acids L-alanine and L-leucine and the aromatic amino acids L-phenylalanine, L-tyrosine and L-tryptophan were irradiated in the solid state to a dose of 3.2 MGy. The degree of decomposition was measured by differential scanning calorimetry (DSC). Furthermore the degree of radioracemization was measured by optical rotatory dispersion (ORD) spectroscopy. From the DSC measurement a radiolysis rate constant k and the half life T1/2 for each amino acid have been determined and extrapolated to a dose of 14 MGy, which corresponds to the expected total dose delivered by the decay of radionuclides to the organic molecules present in comets and asteroids in 4.6×109 years, the age of the Solar System. It is shown that all the amino acids studied can survive a radiation dose of 14 MGy although they are reduced to 1/4-1/5 of their original value they had at the beginning of the history of the Solar System. Consequently, the amount of alanine or leucine found today in the meteorites known as carbonaceous chondrites is just 1/4-1/5 of the amount originally present at the epoch of the formation of the Solar System 4.6×109 years ago. Among the amino acids studied, tyrosine shows the highest radiation resistance while tryptophan does not combine its relatively high radiation resistance with an elevated level of radioracemization resistance. Apart from the exception of tryptophan, it is shown that the radiolysis rate constants k of all the amino acids studied are in reasonable agreement with the radioracemization rate constant krac.

  16. 40 CFR 721.1705 - Benzoic acid, 3-amino-, diazotized, coupled with 6-amino-4-hydroxy-2-naphthalenesulfonic acid...

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Benzoic acid, 3-amino-, diazotized, coupled with 6-amino-4-hydroxy-2-naphthalenesulfonic acid, diazotized, (3-aminophenyl)phosphonic acid and... Significant New Uses for Specific Chemical Substances § 721.1705 Benzoic acid, 3-amino-, diazotized,...

  17. Rotational Study of Natural Amino Acid Glutamine

    Science.gov (United States)

    Varela, Marcelino; Cabezas, Carlos; Alonso, José L.

    2014-06-01

    Recent improvements in laser ablation molecular beam Fourier transform microwave spectroscopy (LA-MB-FTMW) have allowed the investigation of glutamine (COOH-CH(NH2)-CH2-CH2-CONH2), a natural amino acid with a long polar side chain. One dominant structure has been detected in the rotational spectrum. The nuclear quadrupole hyperfine structure of two 14N nuclei has been totally resolved allowing the conclusive identification of the observed species.

  18. Alimentary proteins, amino acids and cholesterolemia.

    Science.gov (United States)

    Blachier, François; Lancha, Antonio H; Boutry, Claire; Tomé, Daniel

    2010-01-01

    Numerous data from both epidemiological and experimental origins indicate that some alimentary proteins and amino acids in supplements can modify the blood LDL cholesterol, HDL cholesterol and total cholesterol. After an initial approval of the health claim for soy protein consumption for the prevention of coronary heart disease, more recently it has been concluded from an overall analysis of literature that isolated soy protein with isoflavones only slightly decrease LDL and total cholesterol. Other plant extracts and also some proteins from animal origin have been reported to exert a lowering effect on blood cholesterol when compared with a reference protein (often casein). The underlying mechanisms are still little understood. Individual amino acids and mixture of amino acids have also been tested (mostly in animal studies) for their effects on cholesterol parameters and on cholesterol metabolism. Methionine, lysine, cystine, leucine, aspartate and glutamate have been tested individually and in combination in different models of either normo or hypercholesterolemic animals and found to be able to modify blood cholesterol and/or LDL cholesterol and/or HDL cholesterol. It is however not known if these results are relevant to human nutrition.

  19. A Green Synthesis of Diisopropyl Phosphoryl Amino Acid

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    In this paper, we report that diisopropyl phosphoryl amino acid could be prepared with reasonable yields under solvent-free condition by adding amino acid to the mixture of diisopropyl phosphite and N-chlorodiisopropylamine.

  20. L-type amino-acid transporter 1 (LAT1): a therapeutic target supporting growth and survival of T-cell lymphoblastic lymphoma/T-cell acute lymphoblastic leukemia.

    Science.gov (United States)

    Rosilio, C; Nebout, M; Imbert, V; Griessinger, E; Neffati, Z; Benadiba, J; Hagenbeek, T; Spits, H; Reverso, J; Ambrosetti, D; Michiels, J-F; Bailly-Maitre, B; Endou, H; Wempe, M F; Peyron, J-F

    2015-06-01

    The altered metabolism of cancer cells is a treasure trove to discover new antitumoral strategies. The gene (SLC7A5) encoding system L amino-acid transporter 1 (LAT1) is overexpressed in murine lymphoma cells generated via T-cell deletion of the pten tumor suppressor, and also in human T-cell acute lymphoblastic leukemia (T-ALL)/lymphoma (T-LL) cells. We show here that a potent and LAT1 selective inhibitor (JPH203) decreased leukemic cell viability and proliferation, and induced transient autophagy followed by apoptosis. JPH203 could also alter the in vivo growth of luciferase-expressing-tPTEN-/- cells xenografted into nude mice. In contrast, JPH203 was nontoxic to normal murine thymocytes and human peripheral blood lymphocytes. JPH203 interfered with constitutive activation of mTORC1 and Akt, decreased expression of c-myc and triggered an unfolded protein response mediated by the C/EBP homologous protein (CHOP) transcription factor associated with cell death. A JPH203-resistant tPTEN-/-clone appeared CHOP induction deficient. We also demonstrate that targeting LAT1 may be an efficient broad spectrum adjuvant approach to treat deadly T-cell malignancies as the molecule synergized with rapamycin, dexamethasone, doxorubicin, velcade and l-asparaginase to alter leukemic cell viability. PMID:25482130

  1. Formation mechanism of coamorphous drug−amino acid mixtures

    DEFF Research Database (Denmark)

    Jensen, Katrine Birgitte Tarp; Larsen, Flemming Hofmann; Cornett, Claus;

    2015-01-01

    Two coamorphous drug−amino acid systems, indomethacin−tryptophan (Ind−Trp) and furosemide−tryptophan Fur−Trp), were analyzed toward their ease of amorphization and mechanism of coamorphization during ball milling. The two mixtures were compared to the corresponding amorphization of the pure drug...

  2. Coordinated Regulation of Dimethylarginine Dimethylaminohydrolase-1 and Cationic Amino Acid Transporter-1 by Farnesoid X Receptor in Mouse Liver and Kidney and Its Implication in the Control of Blood Levels of Asymmetric Dimethylarginine

    OpenAIRE

    Li, Jiang; Wilson, Annette; Gao, Xiang; Kuruba, Ramalinga; Liu, Youhua; Poloyac, Samuel; Pitt, Bruce; Xie, Wen; Li, Song

    2009-01-01

    Asymmetric dimethylarginine (ADMA) is a potent endogenous inhibitor of endothelial nitric-oxide synthase (eNOS), and increased plasma concentrations of ADMA have been regarded as a risk factor for a number of cardiovascular diseases. Circulating ADMA is largely taken up by liver and kidney via system y+ carriers of the cationic amino acid (CAT) family and subsequently metabolized by dimethylarginine dimethylaminohydrolases (DDAHs). As such, agents targeted at enhancing ADMA metabolism may pro...

  3. 40 CFR 721.2584 - Dodecanoic acid, 12-amino-.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Dodecanoic acid, 12-amino-. 721.2584... Substances § 721.2584 Dodecanoic acid, 12-amino-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as dodecanoic acid, 12-amino- (PMN P-98-0823; CAS No....

  4. Metabolism of amino acid amides in Pseudomonas putida ATCC 12633

    NARCIS (Netherlands)

    Hermes, H.F.M.; Croes, L.M.; Peeters, W.P.H.; Peters, P.J.H.; Dijkhuizen, L.

    1993-01-01

    The metabolism of the natural amino acid L-valine, the unnatural amino acids D-valine, and D-, L-phenylglycine (D-, L-PG), and the unnatural amino acid amides D-, L-phenylglycine amide (D, L-PG-NH2) and L-valine amide (L-Val-NH2) was studied in Pseudomonas putida ATCC 12633. The organism possessed c

  5. Origin, Microbiology, Nutrition, and Pharmacology of D-Amino Acids

    Science.gov (United States)

    Exposure of food proteins to certain processing conditions induces two major chemical changes: racemization of all L-amino acids (LAA) to D-amino acids (DAA) and concurrent formation of crosslinked amino acids such as lysinoalanine (LAL). The diet contains both processing-induced and naturally-form...

  6. Amino acid biogeo- and stereochemistry in coastal Chilean sediments

    DEFF Research Database (Denmark)

    Lomstein, Bente Aagaard; Jørgensen, Bo Barker; Schubert, Carsten J.;

    2006-01-01

    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 Concepcion. The contribution of amino acids to total organic...

  7. A Convenient Synthesis of Amino Acid Methyl Esters

    Directory of Open Access Journals (Sweden)

    Yaowu Sha

    2008-05-01

    Full Text Available A series of amino acid methyl ester hydrochlorides were prepared in good toexcellent yields by the room temperature reaction of amino acids with methanol in thepresence of trimethylchlorosilane. This method is not only compatible with natural aminoacids, but also with other aromatic and aliphatic amino acids.

  8. Nature's Starships. I. Observed Abundances and Relative Frequencies of Amino Acids in Meteorites

    CERN Document Server

    Cobb, Alyssa K

    2014-01-01

    The class of meteorites called carbonaceous chondrites are examples of material from the solar system which have been relatively unchanged from the time of their initial formation. These meteorites have been classified according to the temperatures and physical conditions of their parent planetesimals. We collate available data on amino acid abundance in these meteorites and plot the concentrations of different amino acids for each meteorite within various meteorite subclasses. We plot average concentrations for various amino acids across meteorites separated by subclass and petrologic type. We see a predominance in the abundance and variety of amino acids in CM2 and CR2 meteorites. The range in temperature corresponding to these subclasses indicates high degrees of aqueous alteration, suggesting aqueous synthesis of amino acids. Within the CM2 and CR2 subclasses, we identify trends in relative frequencies of amino acids to investigate how common amino acids are as a function of their chemical complexity. The...

  9. Free amino acids in Antarctic aerosol: potential markers for the evolution and fate of marine aerosol

    Directory of Open Access Journals (Sweden)

    E. Barbaro

    2015-01-01

    Full Text Available To investigate the impact of marine aerosols on global climate change it is important to study their chemical composition and size distribution. Amino acids are a component of the organic nitrogen in aerosols, particles containing amino acids have been found to be efficient ice nuclei. The main aim of this study was to investigate the L- and D-free amino acid composition as possible tracers of primary biological production in Antarctic aerosols from three different areas: two continental bases, Mario Zucchelli Station (MZS on the coast of the Ross Sea, Concordia Station at Dome C on the Antarctic Plateau, and the Southern Ocean near the Antarctic continent. Studying the size distribution of amino acids in aerosols allowed us to characterize this component of the water-soluble organic carbon (WSOC in marine aerosols near their source and after long-range transport. The presence of only free L-amino acids in our samples is indicative of the prevalence of phytoplanktonic material. Sampling at these three points allowed us to study the reactivity of these compounds during long-range transport. The mean total amino acid concentration detected at MZS was 11 pmol m−3, a higher percentage of amino acids were found in the fine fraction. The aerosol samples collected at Dome C had the lowest amino acid values (0.7 and 0.8 pmol m−3 and the coarse particles were found to be enriched with amino acids compared to the coastal site. The amino acid composition had also changed suggesting that physical and chemical transformations had occurred during long range transport. During the sampling cruise on the R/V talica on the Southern Ocean, high concentrations of amino acids were found in the total suspended particles, this we attribute to the presence of intact biological material in the sample.

  10. 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

  11. Nutritional and medicinal aspects of D-amino acids.

    Science.gov (United States)

    Friedman, Mendel; Levin, Carol E

    2012-05-01

    This paper reviews and interprets a method for determining the nutritional value of D-amino acids, D-peptides, and amino acid derivatives using a growth assay in mice fed a synthetic all-amino acid diet. A large number of experiments were carried out in which a molar equivalent of the test compound replaced a nutritionally essential amino acid such as L-lysine (L-Lys), L-methionine (L-Met), L-phenylalanine (L-Phe), and L-tryptophan (L-Trp) as well as the semi-essential amino acids L-cysteine (L-Cys) and L-tyrosine (L-Tyr). The results show wide-ranging variations in the biological utilization of test substances. The method is generally applicable to the determination of the biological utilization and safety of any amino acid derivative as a potential nutritional source of the corresponding L-amino acid. Because the organism is forced to use the D-amino acid or amino acid derivative as the sole source of the essential or semi-essential amino acid being replaced, and because a free amino acid diet allows better control of composition, the use of all-amino-acid diets for such determinations may be preferable to protein-based diets. Also covered are brief summaries of the widely scattered literature on dietary and pharmacological aspects of 27 individual D-amino acids, D-peptides, and isomeric amino acid derivatives and suggested research needs in each of these areas. The described results provide a valuable record and resource for further progress on the multifaceted aspects of D-amino acids in food and biological samples.

  12. The Second Extracellular Loop of Pore-Forming Subunits of ATP-Binding Cassette Transporters for Basic Amino Acids Plays a Crucial Role in Interaction with the Cognate Solute Binding Protein(s)▿

    Science.gov (United States)

    Eckey, Viola; Weidlich, Daniela; Landmesser, Heidi; Bergmann, Ulf; Schneider, Erwin

    2010-01-01

    In the thermophile Geobacillus stearothermophilus, the uptake of basic amino acids is mediated by an ABC transporter composed of the substrate binding protein (receptor) ArtJ and a homodimer each of the pore-forming subunit, ArtM, and the nucleotide-binding subunit, ArtP. We recently identified two putative binding sites in ArtJ that might interact with the Art(MP)2 complex, thereby initiating the transport cycle (A. Vahedi-Faridi et al., J. Mol. Biol. 375:448-459, 2008). Here we investigated the contribution of charged amino acid residues in the second extracellular loop of ArtM to contact with ArtJ. Our results demonstrate a crucial role for residues K177, R185, and E188, since mutations to oppositely charged amino acids or glutamine led to a complete loss of ArtJ-stimulated ATPase activity of the complex variants in proteoliposomes. The defects could not be suppressed by ArtJ variants carrying mutations in site I (K39E and K152E) or II (E163K and D170K), suggesting a more complex interplay than that by a single salt bridge. These findings were supported by cross-linking assays demonstrating physical proximity between ArtJ(N166C) and ArtM(E182C). The importance of positively charged residues for receptor-transporter interaction was underscored by mutational analysis of the closely related transporter HisJ/LAO-HisQMP2 of Salmonella enterica serovar Typhimurium. While transporter variants with mutated positively charged residues in HisQ displayed residual ATPase activities, corresponding mutants of HisM could no longer be stimulated by HisJ/LAO. Interestingly, the ATPase activity of the HisQM(K187E)P2 variant was inhibited by l- and d-histidine in detergent, suggesting a role of the residue in preventing free histidine from gaining access to the substrate binding site within HisQM. PMID:20154136

  13. The second extracellular loop of pore-forming subunits of ATP-binding cassette transporters for basic amino acids plays a crucial role in interaction with the cognate solute binding protein(s).

    Science.gov (United States)

    Eckey, Viola; Weidlich, Daniela; Landmesser, Heidi; Bergmann, Ulf; Schneider, Erwin

    2010-04-01

    In the thermophile Geobacillus stearothermophilus, the uptake of basic amino acids is mediated by an ABC transporter composed of the substrate binding protein (receptor) ArtJ and a homodimer each of the pore-forming subunit, ArtM, and the nucleotide-binding subunit, ArtP. We recently identified two putative binding sites in ArtJ that might interact with the Art(MP)(2) complex, thereby initiating the transport cycle (A. Vahedi-Faridi et al., J. Mol. Biol. 375:448-459, 2008). Here we investigated the contribution of charged amino acid residues in the second extracellular loop of ArtM to contact with ArtJ. Our results demonstrate a crucial role for residues K177, R185, and E188, since mutations to oppositely charged amino acids or glutamine led to a complete loss of ArtJ-stimulated ATPase activity of the complex variants in proteoliposomes. The defects could not be suppressed by ArtJ variants carrying mutations in site I (K39E and K152E) or II (E163K and D170K), suggesting a more complex interplay than that by a single salt bridge. These findings were supported by cross-linking assays demonstrating physical proximity between ArtJ(N166C) and ArtM(E182C). The importance of positively charged residues for receptor-transporter interaction was underscored by mutational analysis of the closely related transporter HisJ/LAO-HisQMP(2) of Salmonella enterica serovar Typhimurium. While transporter variants with mutated positively charged residues in HisQ displayed residual ATPase activities, corresponding mutants of HisM could no longer be stimulated by HisJ/LAO. Interestingly, the ATPase activity of the HisQM(K187E)P(2) variant was inhibited by l- and d-histidine in detergent, suggesting a role of the residue in preventing free histidine from gaining access to the substrate binding site within HisQM. PMID:20154136

  14. Genetic analysis of amino acid content in wheat grain

    Indian Academy of Sciences (India)

    Xiaoling Jiang; Peng Wu; Jichun Tian

    2014-08-01

    Complete diallel crosses with five parents of common wheat (Triticum aestivum L.) were conducted to analyse inheritance of 17 amino acid contents by using the genetic model including seed, cytoplasmic, maternal and environment interaction effects on quantitative traits of seeds in cereal crops. The results showed that inheritance of 17 amino acid contents, except tyrosine, was controlled by several genetic systems including seed, cytoplasmic, and maternal effects, and by significant gene × environment interaction effects. Seed-direct additive and maternal effects constituted a major part of genetic effects for lysine, tyrosine, arginine, methionine, and glutamic acid content. Seed-direct additive effect formed main part in inheritance of isoleucine and serine contents. Threonine content was mainly governed by maternal additive effect. The other nine amino acid contents were almost entirely controlled by dominance effects. High general heritability of tyrosine (36.3%), arginine (45.8%), lysine (24.7%) and threonine (21.4%) contents, revealed that it could be effective to improve them by direct selection in progenies from appropriate crosses. Interaction heritability for phenylalanine, proline, and histidine content, which was 36.1%, 39.5% and 25.7%, respectively, was higher than for the other amino acids.

  15. Amino acid uptake in the skeletal muscle measured using [11C]methylaminoisobutyrate (MEAIB) and PET

    International Nuclear Information System (INIS)

    An amino acid analogue, [11C]MeAIB, recently introduced for oncological positron emission tomography (PET) studies, is a highly selective substrate for insulin-sensitive amino acid transport system A. The aim of this study was to study the uptake kinetics of [11C]MeAIB in skeletal muscle in the fasting state and during insulin stimulation. Two dynamic PET studies were carried out in 11 healthy subjects, once in the fasting state and once during euglycaemic hyperinsulinaemia (serum insulin 67±12 mU l-1). Graphical analysis was used to calculate the fractional [11C]MeAIB uptake rate (Ki). Amino acid uptake was estimated by multiplying Ki by the serum amino acid concentration. After tracer injection, rapid uptake in muscle tissue was detected both in the fasting state and during insulin stimulation and femoral muscles were clearly visualised in both studies. In the graphical analysis, the volume of distribution of [11C]MeAIB plotted against normalised plasma time yielded a linear curve (the slope of which = Ki). The fractional [11C]MeAIB uptake rate (Ki) in the femoral muscle regions increased from 0.0070±0.0018 min-1 (mean±SD) in the fasting state to 0.0079±0.0020 min-1 (P-1 (P-1 (P=0.0001) during hyperinsulinaemia. The calculated skeletal muscle total amino acid uptake and the uptake of the six amino acids typically using system A were similar in the fasting state and during insulin clamp (17.1±3.2 vs 17.7±3.7 μmol kg-1 min-1, NS, and 5.0±1.3 vs 5.0±1.4 μmol kg-1 min-1, NS, respectively). The uptake rates correlated with perfusion both in the fasting state and during hyperinsulinaemia (P11C]MeAIB PET appears to be a feasible method for measurement of amino acid uptake in human skeletal muscle. As a tracer that is not metabolised in the tissues, [11C]MeAIB provides simple modelling and robust data analysis and thus provides a means to investigate amino acid uptake into muscle tissue in various disease conditions known to affect protein metabolism. (orig.)

  16. Protein and Amino Acid Requirements during Pregnancy.

    Science.gov (United States)

    Elango, Rajavel; Ball, Ronald O

    2016-07-01

    Protein forms an essential component of a healthy diet in humans to support both growth and maintenance. During pregnancy, an exceptional stage of life defined by rapid growth and development, adequate dietary protein is crucial to ensure a healthy outcome. Protein deposition in maternal and fetal tissues increases throughout pregnancy, with most occurring during the third trimester. Dietary protein intake recommendations are based on factorial estimates because the traditional method of determining protein requirements, nitrogen balance, is invasive and undesirable during pregnancy. The current Estimated Average Requirement and RDA recommendations of 0.88 and 1.1 g · kg(-1) · d(-1), respectively, are for all stages of pregnancy. The single recommendation does not take into account the changing needs during different stages of pregnancy. Recently, with the use of the minimally invasive indicator amino acid oxidation method, we defined the requirements to be, on average, 1.2 and 1.52 g · kg(-1) · d(-1) during early (∼16 wk) and late (∼36 wk) stages of pregnancy, respectively. Although the requirements are substantially higher than current recommendations, our values are ∼14-18% of total energy and fit within the Acceptable Macronutrient Distribution Range. Using swine as an animal model we showed that the requirements for several indispensable amino acids increase dramatically during late gestation compared with early gestation. Additional studies should be conducted during pregnancy to confirm the newly determined protein requirements and to determine the indispensable amino acid requirements during pregnancy in humans. PMID:27422521

  17. Comparative Amino Acid Sequences of Dengue Viruses

    OpenAIRE

    Haishi, Shozo; TANAKA Mariko; Igarashi, Akira

    1990-01-01

    Amino acid (AA) sequences of 4 serotype of dengue viruses deduced from their nucleotide (nt) sequences of genomic RNA were analyzed for each genome segment and each stretch of 10 AA residues. Precursor of membrane protein (pM), and 4 nonstructural proteins (NS1, NS3, NS4B, NS5) were highly conserved, while another nonstructural protein (NS2A) was least conserved among 5 strains of dengue viruses. When homology was compared among heterotypic viruses, type 1 and type 3 dengue viruses showed clo...

  18. D-Amino Acids Trigger Biofilm Disassembly

    OpenAIRE

    Kolodkin-Gal, Illana; Romero, Diego; Cao, Shugeng; Clardy, Jon; Kolter, Roberto; Losick, Richard

    2010-01-01

    Bacteria form communities known as biofilms, which disassemble over time. Here we found that prior to biofilm disassembly Bacillus subtilis produced a factor that prevented biofilm formation and could break down existing biofilms. The factor was shown to be a mixture of D-leucine, D-methionine, D-tyrosine and D-tryptophan that could act at nanomolar concentrations. D-amino acid treatment caused the release of amyloid fibers that linked cells in the biofilm together. Mutants able to form biofi...

  19. Photoinduced dynamics in protonated aromatic amino acid

    CERN Document Server

    Grégoire, Gilles; Barat, Michel; Fayeton, Jacqueline; Dedonder-Lardeux, Claude; Jouvet, Christophe

    2008-01-01

    UV photoinduced fragmentation of protonated aromatics amino acids have emerged the last few years, coming from a situation where nothing was known to what we think a good understanding of the optical properties. We will mainly focus this review on the tryptophan case. Three groups have mostly done spectroscopic studies and one has mainly been involved in dynamics studies of the excited states in the femtosecond/picosecond range and also in the fragmentation kinetics from nanosecond to millisecond. All these data, along with high level ab initio calculations, have shed light on the role of the different electronic states of the protonated molecules upon the fragmentation mechanisms.

  20. Study on nonlinear kinetic and thermodynamics of oscillating reaction of amino Acid-BrO{3/-}-Mn2+-H2SO4-acetone system

    Science.gov (United States)

    Li, Zongxiao; Yuan, Chunlan

    2011-08-01

    With the help of the kinetic parameters (the rate constant ( k in k p) and the apparent activation energy ( E in E p) of the oscillatory induction period and oscillation period) of the oscillating reaction using thirteen amino acids, leucine (Leu), threonine (Thr), arginine (Arg), lysine (Lys), histidine (His), alanine (Ala), glutamine (Glu), glycine (Gly), methionine (Met), cystine (Cys), tryptophan (Trp), serine (Ser) and tyrosine (Tyr), as organic substrates in amino acid-BrO{3/-}-Mn2+-H2SO4-acetone system, then based on the Oregonator model and the thermodynamics theory on irreversible process, the thermodynamic function (Δ H in, Δ G in, Δ S in and Δ H p, Δ G p, Δ S p) of these oscillating system are studied. The results indicate the entropy Δ S of these oscillating reaction are negative, thereby it is proved that the oscillating reaction is a noequilibrium system with dissipation structure in agreement with the character of the oscillating reaction from disorder to order in irreversible thermodynamics. These are satisfactorily to explain the experimental phenomena.

  1. Extraterrestrial Amino Acids in the Almahata Sitta Meteorite

    Science.gov (United States)

    Glavin, Daniel P.; Aubrey, Andrew D.; Callahan, Michael P.; Dworkin, Jason P.; Elsila, Jamie E.; Parker, Eric T.; Bada, Jeffrey L.

    2010-01-01

    Amino acid analysis of a meteorite fragment of asteroid 2008 TC3 called Almahata Sitta was carried out using reverse-phase liquid chromatography coupled with UV fluorescence detection and time-of-flight mass spectrometry (LC-FD/ToF-MS) as part of a sample analysis consortium. LC-FD/ToF-MS analyses of hot-water extracts from the meteorite revealed a complex distribution of two- to seven-carbon aliphatic amino acids and one- to three-carbon amines with abundances ranging from 0.5 to 149 parts-per-billion (ppb). The enantiomeric ratios of the amino acids alanine, R-amino-n-butyric acid (beta-ABA), 2-amino-2-methylbutanoic acid (isovaline), and 2-aminopentanoic acid (norvaline) in the meteorite were racemic (D/L approximately 1), indicating that these amino acids are indigenous to the meteorite and not terrestrial contaminants. Several other non-protein amino acids were also identified in the meteorite above background levels including alpha-aminoisobutyric acid (alpha-AIB), 4-amino-2- methylbutanoic acid, 4-amino-3-methylbutanoic acid, and 3-, 4-, and 5-aminopentanoic acid. The total abundances of isovaline and alpha-AIB in Almahata Sitta are 1000 times lower than the abundances of these amino acids found in the CM carbonaceous chondrite Murchison. The extremely low abundances and unusual distribution of five carbon amino acids in Almahata Sitta compared to Cl, CM, and CR carbonaceous chondrites may reflect extensive thermal alteration of amino acids on the parent asteroid by partial melting during formation or subsequent impact shock heating. It is also possible that amino acids were synthesized by catalytic reactions on the parent body after asteroid 2008 TC3 cooled to lower temperatures.

  2. Progress Toward an Enceladus Amino Acid Sampler Astrobiology Instrument

    Science.gov (United States)

    Kirby, J. P.; Willis, P. A.; Blacksberg, J.

    2012-12-01

    The development of a new astrobiolgoy instrument for exploring the trace chemical composition of the Enceladus jets and plume, and the e-ring of Saturn is presented. The Enceladus amino acid sampler (EAAS) allows for detection of amino acids using optical Raman spectroscopy integrated with a sample pre-concentration system. The pre-concentration process facilitates the delivery of a sample to a mass spectrometer for detection of specific amino acids. The initial EAAS design utilizes lab-on-a-breadboard components where a sample inlet, sample outlet, reagents, controllers, pumps, valves and pre-concentration column for the EAAS prototype are all assembled on a 5" x 7" breadboard. The pre-concentration process is controlled using automation scripts and software. An optical window allows a Raman spectrometer to directly monitor the pre-concentration of amino acids in a filter/column loaded with of a strong cation exchange resin. Initial samples to demonstrate EAAS simulate the conditions of Don Juan Pond, one of the coldest and saltiest bodies of liquid water on Earth, located in the Wright Valley of Antarctica. This EAAS development is an important step toward a new type of astrobiology science instrument that is capable of operating on a spacecraft in flight or in orbit.

  3. Amino acids as co-amorphous excipients for simvastatin and glibenclamide

    DEFF Research Database (Denmark)

    Laitinen, Riikka; Löbmann, Korbinian; Grohganz, Holger;

    2014-01-01

    to a few drugs and amino acids. To facilitate the rational selection of amino acids, the practical importance of the amino acid coming from the biological target site of the drug (and associated intermolecular interactions) needs to be established. In the present study, the formation of co......-amorphous systems using cryomilling and combinations of two poorly water-soluble drugs (simvastatin and glibenclamide) with the amino acids aspartic acid, lysine, serine, and threonine was investigated. Solid-state characterization with X-ray powder diffraction, differential scanning calorimetry, and Fourier...

  4. Conformational properties of oxazoline-amino acids

    Science.gov (United States)

    Staś, Monika; Broda, Małgorzata A.; Siodłak, Dawid

    2016-04-01

    Oxazoline-amino acids (Xaa-Ozn) occur in natural peptides of potentially important bioactivity. The conformations of the model compounds: Ac-(S)-Ala-Ozn(4R-Me), Ac-(S)-Ala-Ozn(4S-Me), and (gauche+, gauche-, anti) Ac-(S)-Val-Ozn(4R-Me) were studied at meta-hybrid M06-2X/6-311++G(d,p) method including solvent effect. Boc-L-Ala-L-Ozn-4-COOMe and Boc-L-Val-L-Ozn-4-COOMe were synthesized and studied by FT-IR and NMR-NOE methods. The conformations in crystal state were gathered from the Cambridge Structural Data Base. The main conformational feature of the oxazoline amino acids is the conformation β2 (ϕ,ψ ∼ -161°, -6°), which predominates in weakly polar environment and still is accessible in polar surrounding. The changes of the conformational preferences towards the conformations αR (ϕ,ψ ∼ -70°, -15°) and then β (ϕ,ψ ∼ -57°, -155°) are observed with increase of the environment polarity.

  5. Plasma free amino acid kinetics in rainbow trout (Oncorhynchus mykiss) using a bolus injection of 15N-labeled amino acids.

    Science.gov (United States)

    Robinson, Jacob William; Yanke, Dan; Mirza, Jeff; Ballantyne, James Stuart

    2011-02-01

    To gain insight into the metabolic design of the amino acid carrier systems in fish, we injected a bolus of (15)N amino acids into the dorsal aorta in mature rainbow trout (Oncorhynchus mykiss). The plasma kinetic parameters including concentration, pool size, rate of disappearance (R(d)), half-life and turnover rate were determined for 15 amino acids. When corrected for metabolic rate, the R(d) values obtained for trout for most amino acids were largely comparable to human values, with the exception of glutamine (which was lower) and threonine (which was higher). R(d) values ranged from 0.9 μmol 100 g(-1) h(-1) (lysine) to 22.1 μmol 100 g(-1) h(-1) (threonine) with most values falling between 2 and 6 μmol 100 g(-1) h(-1). There was a significant correlation between R(d) and the molar proportion of amino acids in rainbow trout whole body protein hydrolysate. Other kinetic parameters did not correlate significantly with whole body amino acid composition. This indicates that an important design feature of the plasma-free amino acids system involves proportional delivery of amino acids to tissues for protein synthesis.

  6. Adsorption of amino acids by fullerenes and fullerene nanowhiskers

    Science.gov (United States)

    Hashizume, Hideo; Hirata, Chika; Fujii, Kazuko; Miyazawa, Kun'ichi

    2015-12-01

    We have investigated the adsorption of some amino acids and an oligopeptide by fullerene (C60) and fullerene nanowhiskers (FNWs). C60 and FNWs hardly adsorbed amino acids. Most of the amino acids used have a hydrophobic side chain. Ala and Val, with an alkyl chain, were not adsorbed by the C60 or FNWs. Trp, Phe and Pro, with a cyclic structure, were not adsorbed by them either. The aromatic group of C60 did not interact with the side chain. The carboxyl or amino group, with the frame structure of an amino acid, has a positive or negative charge in solution. It is likely that the C60 and FNWs would not prefer the charged carboxyl or amino group. Tri-Ala was adsorbed slightly by the C60 and FNWs. The carboxyl or amino group is not close to the center of the methyl group of Tri-Ala. One of the methyl groups in Tri-Ala would interact with the aromatic structure of the C60 and FNWs. We compared our results with the theoretical interaction of 20 bio-amino acids with C60. The theoretical simulations showed the bonding distance between C60 and an amino acid and the dissociation energy. The dissociation energy was shown to increase in the order, Val acids did not show a different adsorption behavior compared with other amino acids. The adsorptive behavior of mono-amino acids might be different from that of polypeptides.

  7. Influence of Diet Balanced with Essential Amino Acids / Keto Acid Analogs and High-Nutrient Blend on the Progression of Renal Failure in Patients in the Pre-Dialysis Stage of Chronic Kidney Disease Caused by Systemic Autoimmune Diseases

    OpenAIRE

    I I Aleksandrova; Mikhailov, A. A.; Lyudmila Y. Milovanova; Yury S. Milovanov

    2013-01-01

    The aim of the study was to evaluate the effect of a low protein diet (LPD) balanced with essential amino acids (EAA) / keto acid analogs (KAA) and protein “SUPRO-XT 219D” in the composition of the high-energy nutrient blend (HENB) for slow down of renal failure in patients in the pre-dialysis stage of chronic kidney disease (CKD) induced by systemic autoimmune diseases (SAD).Material and Methods: In this study, 46 patients (35 with systemic lupus erythematosus and 15 with various forms of sy...

  8. Turkey-hen amino acid composition of brain and eyes

    International Nuclear Information System (INIS)

    The amino acids composition of the brain and eyes of the mature Turkey-hen (Meleagris gallopavo L.), were determined on dry weight basis. Total essential amino acids ranged from 35.1-36.0 g/100 g as 49.5-49.8% of the total amino acids. The amino acid score showed that lysine ranged from 0.76-0.91 (on whole hen.s egg comparison), 0.85-1.03 (on provisional essential amino acid scoring pattern), and 0.81-0.98 (on suggested requirement of the essential amino acid of a preschool child). The predicted protein efficiency ratio was 1.94-2.41, whilst essential amino acid index range was 1.06-1.08 and the calculated isoelectric point range was 3.97-4.18. The correlation coefficient (rxy) was positively high and significant at r = 0.01 for the total amino acids, amino acid scores (on the whole hen.s egg comparisons made) and the isoelectric point. On the whole, the eyes were better in 12/18 or 66.7% parameters of the amino acids than the brain of Turkey-Hen. (author)

  9. Characterisation of CMP-sialic acid transporter substrate recognition

    NARCIS (Netherlands)

    Maggioni, A.; Itzstein, M. von; Guzman, I.B. Rodriguez; Ashikov, A.M.; Stephens, A.S.; Haselhorst, T.; Tiralongo, J.

    2013-01-01

    CMP-sialic acid transporter: We report an in-depth, multidisciplinary, structural study that has identified the amino acid residues intimately involved in CMP-sialic acid transporter (CST) substrate specificity. Our data provide a significant contribution towards a better understanding the structure

  10. Oncogenicity of L-type amino-acid transporter 1 (LAT1) revealed by targeted gene disruption in chicken DT40 cells: LAT1 is a promising molecular target for human cancer therapy

    International Nuclear Information System (INIS)

    Highlights: → We established LAT1 amino-acid transporter-disrupted DT40 cells. → LAT1-disrupted cells showed slow growth and lost the oncogenicity. → siRNA and mAb inhibited human tumor growth in vitro and in vivo. → LAT1 is a promising target molecule for cancer therapy. -- Abstract: L-type amino-acid transporter 1 (LAT1) is the first identified light chain of CD98 molecule, disulfide-linked to a heavy chain of CD98. Following cDNA cloning of chicken full-length LAT1, we have constructed targeting vectors for the disruption of chicken LAT1 gene from genomic DNA of chicken LAT1 consisting of 5.4 kb. We established five homozygous LAT1-disrupted (LAT1-/-) cell clones, derived from a heterozygous LAT1+/- clone of DT40 chicken B cell line. Reactivity of anti-chicken CD98hc monoclonal antibody (mAb) with LAT1-/- DT40 cells was markedly decreased compared with that of wild-type DT40 cells. All LAT1-/- cells were deficient in L-type amino-acid transporting activity, although alternative-splice variant but not full-length mRNA of LAT1 was detected in these cells. LAT1-/- DT40 clones showed outstandingly slow growth in liquid culture and decreased colony-formation capacity in soft agar compared with wild-type DT40 cells. Cell-cycle analyses indicated that LAT1-/- DT40 clones have prolonged cell-cycle phases compared with wild-type or LAT1+/- DT40 cells. Knockdown of human LAT1 by small interfering RNAs resulted in marked in vitro cell-growth inhibition of human cancer cells, and in vivo tumor growth of HeLa cells in athymic mice was significantly inhibited by anti-human LAT1 mAb. All these results indicate essential roles of LAT1 in the cell proliferation and occurrence of malignant phenotypes and that LAT1 is a promising candidate as a molecular target of human cancer therapy.

  11. Alpha-amino acid behaves differently from beta- or gamma-amino acids as treated by trimetaphosphate.

    Science.gov (United States)

    Gao, X; Liu, Y; Xu, P X; Cai, Y M; Zhao, Y F

    2008-01-01

    The condensation reactions of sodium trimetaphosphate with single amino acids, namely glycine, L-alanine, beta-alanine and gamma-aminobutyric acid or pairs of these amino acids were reinvestigated by electrospray ion-trap mass spectrometry and high performance liquid chromatography. It was found when mixtures were treated by sodium trimetaphosphate only in the presence of alpha-amino acid dipeptides were formed. Without addition of alpha-amino acids, the beta-amino acid or gamma-aminobutyric acid could not form peptide either by themselves or with their mixtures under the same conditions. From the data it is concluded that phosphate might select alpha-amino acids to produce the peptides being important precursors for the origin of life. PMID:17973074

  12. The effect of uric acid on the transport activity of placental system A%尿酸对胎盘系统A转运活性的影响

    Institute of Scientific and Technical Information of China (English)

    孙湛博; 杨琳; 宋薇薇

    2012-01-01

    目的 探讨尿酸对胎盘系统A氨基酸转运活性的影响.方法 2009年9月至2011年1月在中国医科大学附属盛京医院取无妊娠期并发症(如高血压、糖尿病等)与合并症的孕妇剖宫产分娩,体重正常的健康足月儿胎盘组织为研究对象.体外实验依据不同的尿酸质量浓度分为尿酸质量浓度178.5 μmol/L组、297.5μmol/L组、416.5 μmol/L组,以及不加尿酸的对照组.采用胎盘绒毛片段培养技术及同位素掺入技术对系统A的转运活性进行测定.结果 3种不同质量浓度尿酸组孵育2h后培养液中雌二醇质量浓度分别为(166.75±9.45)、(167.32±8.56)及(160.01±9.29) pmol/L,与对照组(170.03±11.32)pmol/L比较,差异均无统计学意义(P>0.05).3组不同尿酸质量浓度组分别与对照组系统A的氨基酸转运活性比较,差异均有统计学意义(P均<0.05).4组之间系统A的转运活性比较,差异有统计学意义(P均<0.05).结论 尿酸可能对胎盘系统A的氨基酸转运活性具有重要影响,这种影响具有浓度依赖性,而这一影响可能是高尿酸血症时引起低出生体重的重要机制之一.%Objective To explore the effect of uric acid on placental system A amino acid transport activity. Methods Between Sep. 2009 and Jan. 2011 in China Medical University Affiliated Shengjing Hospital placental samples were taken from pregnancies, which had no history of obstetric or metabolic disease and had cesarean section delivery to normal healthy full-term birth. According to different uric acid concentration, placental samples were divided into four groups; Groupl, control group; Group 2, uric acid concentration was 178. 5μmol/L; Group 3, uric acid concentration was 297. 5μmol/L and Group 4, uric acid concentration was 416. 5μmol/L. System A transport activity was detected by placenta fragment culture technique and isotope incorporation. Results After 2-h culture by different concentrations of uric acid, the estradiol

  13. Extraterrestrial Amino Acids in the Almahata Sitta Meteorite

    Science.gov (United States)

    Glavin, Daniel P.; Aubrey, Andrew D.; Callahan, Michael P.; Dworkin, Jason P.; Elsila, Jamie E.; Parker, Eric T.; Bada, Jeffrey L.

    2009-01-01

    Amino acid analysis of a meteorite fragment of asteroid 2008 TC(sub 3) called Almahata Sitta was carried out using reverse-phase high-perfo rmance liquid chromatography coupled with UV fluorescence detection a nd time-of-flight mass spectrometry (HPLC-FD/ToF-MS) as part of a sam ple analysis consortium. HPLC analyses of hot-water extracts from the meteorite revealed a complex distribution of two- to six-carbon aliph atic amino acids and one- to three carbon amines with abundances rang ing from 0.5 to 149 parts-per-billion (ppb). The enantiomeric ratios of the amino acids alanine, Beta-amino-n-butyric acid (Beta-ABA), 2-amino-2- methylbutanoic acid (isovaline), and 2-aminopentanoic acid (no rvaline) in the meteorite were racemic (D/L approximately 1), indicat ing that these amino acids are indigenous to the meteorite and not te rrestrial contaminants. Several other non-protein amino acids were also identified in the meteorite above background levels including alpha -aminoisobutyric acid (alpha-AIB), 4-amino-2- methybutanoic acid, 4-a mino-3-methylbutanoic acid, and 3-, 4-, and 5-aminopentanoic acid. Th e total abundances of isovaline and AlB in Almahata Sitta are approximately 1000 times lower than the abundances of these amino acids found in the CM carbonaceous meteorite Murchison. The extremely love abund ances and unusual distribution of five carbon amino acids in Almahata Sitta compared to Cl, CM, and CR carbonaceous meteorites and may be due to extensive thermal alteration of amino acids on the parent aster oid by partial melting during formation or impact shock heating.

  14. THIN-LAYER SEPARATION OF CITRIC ACID CYCLE INTERMEDIATES, LACTIC ACID, AND THE AMINO ACID TAURINE

    Science.gov (United States)

    This paper describes a two-dimensional mixed-layer method for separating citric acid cycle intermediates, lactic acid and the amino acid taurine. The method cleanly separates all citric acid cycle intermediates tested, excepting citric acid and isocitric acid. The solvents are in...

  15. 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...

  16. Stereoselective synthesis of stable-isotope-labeled amino acids

    Energy Technology Data Exchange (ETDEWEB)

    Unkefer, C.J.; Martinez, R.A.; Silks, L.A. III [Los Alamos National Laboratory, NM (United States); Lodwig, S.N. [Centralia College, WA (United States)

    1994-12-01

    For magnetic resonance and vibrational spectroscopies to reach their full potential, they must be used in combination with sophisticated site-specific stable isotope labeling of biological macromolecules. Labeled amino acids are required for the study of the structure and function of enzymes and proteins. Because there are 20 common amino acids, each with its own distinguishing chemistry, they remain a synthetic challenge. The Oppolzer chiral auxiliary provides a general tool with which to approach the synthesis of labeled amino acids. By using the Oppolzer auxiliary, amino acids can be constructed from several small molecules, which is ideal for stable isotope labeling. In addition to directing the stereochemistry at the {alpha}-carbon, the camphorsultam can be used for stereo-specific isotope labeling at prochiral centers in amino acids. By using the camphorsultam auxiliary we have the potential to synthesize virtually any isotopomer of all of the common amino acids.

  17. Cytokines: muscle protein and amino acid metabolism

    DEFF Research Database (Denmark)

    van Hall, Gerrit

    2012-01-01

    of IL-6 on the regulation of muscle protein metabolism but indirectly via IL-6 reducing amino acid availability. SUMMARY: Recent studies suggest that the best described cytokines TNF-α and IL-6 are unlikely to be the major direct mediators of muscle protein loss in inflammatory diseases. However....... However, this does not seem applicable for inflammatory diseases or human models of sepsis, in which the enhanced imbalance between these two processes is observed within an enhanced, normal or reduced muscle protein turnover.......PURPOSE OF REVIEW: This review highlights the role of cytokines, in particular tumour necrosis factor alpha (TNF-α) and interleukin-6 (IL-6), in relation to the nature of human in-vivo muscle wasting in disease. RECENT FINDINGS: Infusion of human TNF-α and IL-6 in healthy individuals, acutely...

  18. Diversity of amino acids in a typical chernozem of Moldova

    Science.gov (United States)

    Frunze, N. I.

    2014-12-01

    The content and composition of the amino acids in typical chernozems were studied. The objects of the study included a reference soil under an old fallow and three variants under fodder crop rotations: not fertilized, with mineral fertilizers, and with organic fertilizers. The contents of 18 amino acids were determined in these soils. The amino acids were extracted by the method of acid hydrolysis and identified by the method of ion-exchange chromatography. The total content of most of the amino acids was maximal in the reference soil; it was much lower in the cultivated soils and decreased in the following sequence: organic background > mineral background > no fertilization. The diversity of amino acids was evaluated quantitatively using different parameters applied in ecology for estimating various aspects of the species composition of communities (Simpson, Margalef, Menhinick, and Shannon's indices). The diversity and contribution of different amino acids to the total pool of amino acids also varied significantly in the studied variants. The maximum diversity of amino acids and maximum evenness of their relative abundance indices were typical of the reference chernozem; these parameters were lower in the cultivated soils. It was concluded that the changes in the structure of the amino acids under the impact of agricultural loads are similar to those that are usually observed under stress conditions.

  19. The Origin of Amino Acids in Lunar Regolith Samples

    Science.gov (United States)

    Cook, Jamie E.; Callahan, Michael P.; Dworkin, Jason P.; Glavin, Daniel P.; McLain, Hannah L.; Noble, Sarah K.; Gibson, Everett K., Jr.

    2016-01-01

    We analyzed the amino acid content of seven lunar regolith samples returned by the Apollo 16 and Apollo 17 missions and stored under NASA curation since collection using ultrahigh-performance liquid chromatography with fluorescence detection and time-of-flight mass spectrometry. Consistent with results from initial analyses shortly after collection in the 1970s, we observed amino acids at low concentrations in all of the curated samples, ranging from 0.2 parts-per-billion (ppb) to 42.7 ppb in hot-water extracts and 14.5 ppb to 651.1 ppb in 6M HCl acid-vapor-hydrolyzed, hot-water extracts. Amino acids identified in the Apollo soil extracts include glycine, D- and L-alanine, D- and L-aspartic acid, D- and L-glutamic acid, D- and L-serine, L-threonine, and L-valine, all of which had previously been detected in lunar samples, as well as several compounds not previously identified in lunar regoliths: -aminoisobutyric acid (AIB), D-and L-amino-n-butyric acid (-ABA), DL-amino-n-butyric acid, -amino-n-butyric acid, -alanine, and -amino-n-caproic acid. We observed an excess of the L enantiomer in most of the detected proteinogenic amino acids, but racemic alanine and racemic -ABA were present in some samples.

  20. Polarographic studies on mixed ligand complexes involving amino acids : ternary systems, Cd-α-alanine-oxalate and Cd-β-alanine-oxalate

    International Nuclear Information System (INIS)

    Ternary complexes of cadmium(II) with oxalate as primary ligand and α- and β-alanines as secondary ligands have been studied polarographically. Formation of three mixed complex species, [Cd(amino acid) (oxalate)], [Cd(amino acid) (oxalate)2] and [Cd(anino acid)2(oxalate)], is observed in each case. The reduction is reversible and diffusion-controlled. The stability constants have been evaluated usino the method of McMasters. The α-alanine complexes are found to be more stable than the corresponding β-alanine complexes. (author)

  1. Addicting diverse bacteria to a noncanonical amino acid.

    Science.gov (United States)

    Tack, Drew S; Ellefson, Jared W; Thyer, Ross; Wang, Bo; Gollihar, Jimmy; Forster, Matthew T; Ellington, Andrew D

    2016-03-01

    Engineered orthogonal translation systems have greatly enabled the expansion of the genetic code using noncanonical amino acids (NCAAs). However, the impact of NCAAs on organismal evolution remains unclear, in part because it is difficult to force the adoption of new genetic codes in organisms. By reengineering TEM-1 β-lactamase to be dependent on a NCAA, we maintained bacterial NCAA dependence for hundreds of generations without escape. PMID:26780407

  2. A new synthetic protocol for coumarin amino acid

    Directory of Open Access Journals (Sweden)

    Xinyi Xu

    2013-02-01

    Full Text Available The hydrochloride of the racemic amino acid (2-(7-hydroxycoumarin-4-ylethylglycine, which can serve as a fluorescent probe in proteins, and two halogen derivatives of it, were synthesized by using a new synthetic protocol in five steps. It is less costly and relatively easy to prepare this kind of fluorescent amino acid with the new synthetic method. Furthermore, it can be applied to synthesize other derivatives of the coumarin amino acid with some specific properties.

  3. Amino acid analysis in biological fluids by GC-MS

    OpenAIRE

    Kaspar, Hannelore

    2009-01-01

    Amino acids are intermediates in cellular metabolism and their quantitative analysis plays an important role in disease diagnostics. A gas chromatography-mass spectrometry (GC-MS) based method was developed for the quantitative analysis of free amino acids as their propyl chloroformate derivatives in biological fluids. Derivatization with propyl chloroformate could be carried out directly in the biological samples without prior protein precipitation or solid-phase extraction of the amino acid...

  4. GLC of amino acids - A survey of contamination.

    Science.gov (United States)

    Rash, J. J.; Gehrke, C. W.; Kuo, K. C.; Kvenvolden, K. A.; Stalling, D. L.; Zumwalt, R. W.

    1972-01-01

    Analyses of biological substances and geochemical samples, of both terrestrial and extraterrestrial origin, are reported for amino acids at the 1-10 nanogram per gram level achieved by gas-liquid and ion-exchange chromatographic methods. These studies have shown that nanogram quantities of amino acids, present in water extracts of geochemical samples or in other samples of low amino acid concentration, can be successfully determined only if the researcher is well aware of the possible sources of contamination.

  5. PHARMACOLOGICAL EFFECTS OF SNAKE VENOM L- AMINO ACID OXIDASES

    OpenAIRE

    Joseph Baby; Rajan Sheeja S; M.V Jeevitha; S.U Ajisha

    2011-01-01

    L-Amino acid oxidases are flavoenzymes which catalyze the stereospecific oxidative deamination of an L-amino acid substrate to a corresponding a-ketoacid with hydrogen peroxide and ammonia production. These enzymes, which are widely distributed in many different organisms, exhibit a marked affinity for hydrophobic amino acids, including phenylalanine, tryptophan, tyrosine, and leucine. Snake venom LAAO induces platelet aggregation and cytotoxicity in various cancer cell lines. The enzyme has ...

  6. 21 CFR 862.1515 - Nitrogen (amino-nitrogen) test system.

    Science.gov (United States)

    2010-04-01

    ... Systems § 862.1515 Nitrogen (amino-nitrogen) test system. (a) Identification. A nitrogen (amino-nitrogen) test system is a device intended to measure amino acid nitrogen levels in serum, plasma, and urine... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Nitrogen (amino-nitrogen) test system....

  7. Free amino acids in atmospheric particulate matter of Venice, Italy

    Science.gov (United States)

    Barbaro, Elena; Zangrando, Roberta; Moret, Ivo; Barbante, Carlo; Cescon, Paolo; Gambaro, Andrea

    2011-09-01

    The concentrations of free amino acids were determined in atmospheric particulate matter from the city of Venice (Italy) in order to better understand their origin. The analysis of aerosol samples was carried out via high-performance liquid chromatography coupled to a triple quadrupole tandem mass spectrometric detector (HPLC/ESI-MS/MS). The internal standard method was used and the analytical procedure was validated by evaluating the trueness, the precision, the recovery, the detection and the quantification limits. The particulate matter was collected using quartz fiber filters and extracted in methanol; after filtration the extract was directly analyzed. Forty samples were collected from April to October 2007 and the average concentrations of free amino acids in the aerosol were: alanine 35.6 pmol m -3, aspartic acid 31.1 pmol m -3, glycine 30.1 pmol m -3, glutamic acid 32.5 pmol m -3, isoleucine 2.4 pmol m -3, leucine 2.7 pmol m -3, methionine, cystine and 3-hydroxy-proline below the limit of detection, phenylalanine 2.8 pmol m -3, proline 43.3 pmol m -3, serine 8.6 pmol m -3, threonine 2.8 pmol m -3, tyrosine 1.7 pmolm -3, valine 3.8 pmol m -3, asparagine 70.2 pmol m -3, glutamine 38.0 pmol m -3, 4-hydroxy-proline 2.5 pmol m -3, methionine sulfoxide 1.1 pmol m -3, and methionine sulfone 0.1 pmol m -3. The total average concentration of these free amino acids in aerosol samples of Venice Lagoon was 334 pmol m -3. The temporal evolution and multivariate analysis indicated the photochemical origin of 4-hydroxy-proline and methionine sulfoxide and for other compounds an origin further away from the site of sampling, presumably reflecting transport from terrestrial sources.

  8. Alleviation of temperature-sensitive secretion defect of Pseudomonas fluorescens ATP-binding cassette (ABC) transporter, TliDEF, by a change of single amino acid in the ABC protein, TliD.

    Science.gov (United States)

    Eom, Gyeong Tae; Oh, Joon Young; Park, Ji Hyun; Lim, Hye Jin; Lee, So Jeong; Kim, Eun Young; Choi, Ji-Eun; Jegal, Jonggeon; Song, Bong Keun; Yu, Ju-Hyun; Song, Jae Kwang

    2016-09-01

    An ABC transporter, TliDEF, from Pseudomonas fluorescens SIK W1, mediates the secretion of its cognate lipase, TliA, in a temperature-dependent secretion manner; the TliDEF-mediated secretion of TliA was impossible at the temperatures over 33°C. To isolate a mutant TliDEF capable of secreting TliA at 35°C, the mutagenesis of ABC protein (TliD) was performed. The mutated tliD library where a random point mutation was introduced by error-prone PCR was coexpressed with the wild-type tliE, tliF and tliA in Escherichia coli. Among approximately 10,000 colonies of the tliD library, we selected one colony that formed transparent halo on LB-tributyrin plates at 35°C. At the growth temperature of 35°C, the selected mutant TliD showed 1.75 U/ml of the extracellular lipase activity, while the wild-type TliDEF did not show any detectable lipase activity in the culture supernatant of E. coli. Moreover, the mutant TliD also showed higher level of TliA secretion than the wild-type TliDEF at other culture temperatures, 20°C, 25°C and 30°C. The mutant TliD had a single amino acid change (Ser287Pro) in the predicted transmembrane region in the membrane domain of TliD, implying that the corresponding region of TliD was important for causing the temperature-dependent secretion of TliDEF. These results suggested that the property of ABC transporter could be changed by the change of amino acid in the ABC protein. PMID:27033673

  9. Branched-chain amino acids and brain function.

    Science.gov (United States)

    Fernstrom, John D

    2005-06-01

    Branched-chain amino acids (BCAAs) influence brain function by modifying large, neutral amino acid (LNAA) transport at the blood-brain barrier. Transport is shared by several LNAAs, notably the BCAAs and the aromatic amino acids (ArAAs), and is competitive. Consequently, when plasma BCAA concentrations rise, which can occur in response to food ingestion or BCAA administration, or with the onset of certain metabolic diseases (e.g., uncontrolled diabetes), brain BCAA concentrations rise, and ArAA concentrations decline. Such effects occur acutely and chronically. Such reductions in brain ArAA concentrations have functional consequences: biochemically, they reduce the synthesis and the release of neurotransmitters derived from ArAAs, notably serotonin (from tryptophan) and catecholamines (from tyrosine and phenylalanine). The functional effects of such neurochemical changes include altered hormonal function, blood pressure, and affective state. Although the BCAAs thus have biochemical and functional effects in the brain, few attempts have been made to characterize time-course or dose-response relations for such effects. And, no studies have attempted to identify levels of BCAA intake that might produce adverse effects on the brain. The only "model" of very high BCAA exposure is a very rare genetic disorder, maple syrup urine disease, a feature of which is substantial brain dysfunction but that probably cannot serve as a useful model for excessive BCAA intake by normal individuals. Given the known biochemical and functional effects of the BCAAs, it should be a straightforward exercise to design studies to assess dose-response relations for biochemical and functional effects and, in this context, to explore for adverse effect thresholds. PMID:15930466

  10. Method for Enzyme Design with Genetically Encoded Unnatural Amino Acids.

    Science.gov (United States)

    Hu, C; Wang, J

    2016-01-01

    We describe the methodologies for the design of artificial enzymes with genetically encoded unnatural amino acids. Genetically encoded unnatural amino acids offer great promise for constructing artificial enzymes with novel activities. In our studies, the designs of artificial enzyme were divided into two steps. First, we considered the unnatural amino acids and the protein scaffold separately. The scaffold is designed by traditional protein design methods. The unnatural amino acids are inspired by natural structure and organic chemistry methods, and synthesized by either organic chemistry methods or enzymatic conversion. With the increasing number of published unnatural amino acids with various functions, we described an unnatural amino acids toolkit containing metal chelators, redox mediators, and click chemistry reagents. These efforts enable a researcher to search the toolkit for appropriate unnatural amino acids for the study, rather than design and synthesize the unnatural amino acids from the beginning. After the first step, the model enzyme was optimized by computational methods and directed evolution. Lastly, we describe a general method for evolving aminoacyl-tRNA synthetase and expressing unnatural amino acids incorporated into a protein. PMID:27586330

  11. Analysis of amino acids network based on distance matrix

    Science.gov (United States)

    Ali, Tazid; Akhtar, Adil; Gohain, Nisha

    2016-06-01

    In this paper we have constructed a distance matrix of the amino acids. The distance is defined based on the relative evolutionary importance of the base position of the corresponding codons. From this distance matrix a network of the amino acids is obtained. We have argued that this network depicts the evolutionary pattern of the amino acids. To examine the relative importance of the amino acids with respect to this network we have discussed different measures of centrality. We have also investigated the correlation coefficients between different measures of centrality. Further we have explored clustering coefficient as well as degree of distribution.

  12. Abiotic racemization kinetics of amino acids in marine sediments

    DEFF Research Database (Denmark)

    Steen, Andrew; Jørgensen, Bo Barker; Lomstein, Bente Aagaard

    2013-01-01

    Enantiomeric ratios of amino acids can be used to infer the sources and composition of sedimentary organic matter. Such inferences, however, rely on knowing the rates at which amino acids in sedimentary organic racemize abiotically. Based on a heating experiment, we report Arrhenius parameters...... between different amino acids or depths. These results can be used in conjunction with measurements of sediment age to predict the ratio of D:L amino acids due solely to abiotic racemization of the source material, deviations from which can indicate the abundance and turnover of active microbial...

  13. Which Amino Acids Should Be Used in Prebiotic Chemistry Studies?

    Science.gov (United States)

    Zaia, Dimas A. M.; Zaia, Cássia Thaïs B. V.; de Santana, Henrique

    2008-12-01

    The adsorption of amino acids on minerals and their condensation under conditions that resemble those of prebiotic earth is a well studied subject. However, which amino acids should be used in these experiments is still an open question. The main goal of this review is to attempt to answer this question. There were two sources of amino acids for the prebiotic earth: (1) exogenous—meaning that the amino acids were synthesized outside the earth and delivered to our planet by interplanetary dust particles (IDPs), meteorites, comets, etc. and (2) endogenous—meaning that they were synthesized on earth in atmospheric mixtures, hydrothermal vents, etc. For prebiotic chemistry studies, the use of a mixture of amino acids from both endogenous and exogenous sources is suggested. The exogenous contribution of amino acids to this mixture is very different from the average composition of proteins, and contains several non-protein amino acids. On the other hand, the mixture of amino acids from endogenous sources is seems to more closely resemble the amino acid composition of terrestrial proteins.

  14. Synthesis of novel fullerene α-amino acid conjugates

    Institute of Scientific and Technical Information of China (English)

    Jing Zhang; Yan Xia Wang; Feng Kang; Ying Ya Shao; Zong Jie Li; Xin Lin Yang

    2008-01-01

    Aspartie acid and glutamic acid with protected α-amino and α-carboxyl groups had been used to react with the activated hydroxyl group of N-substituted 3,4-fuUero pyrrolidine.The products were deprotected,affording two monofullerene α-amino acids,monofullerene aspartic acid(mFas)and monofullerene glutamic acid(mFgu).Then a bifullerene glutamic acid conjugate (bFguC)was synthesized by reaction of mFgu containing protected amino group with N-subsfimted 3,4-fullero pyrrolidine.

  15. Synthesis, Characterization and Structure of Chiral Amino Acids and Their Corresponding Amino Alcohols with Camphoric Backbone

    Institute of Scientific and Technical Information of China (English)

    QIAN Hui-Fen; HUANG Wei; LI Hui-Hui; YAO Cheng

    2006-01-01

    Chiral amino acids and their corresponding amino alcohols bearing camphoric backbone were prepared from D-(+)-camphoric imide and characterized by infrared, elemental analysis, ESI-MS, and NMR measurements. Among them, one intermediate (lS,3R)-3-amino-2,2,3-trimethyl cyclopentane-1-carboxylic acid hydrochloride 3 was structurally elucidated by X-ray diffraction techniques. Versatile intermolecular hydrogen bonding interactions observed in its packing structure result in a two-dimensional framework.

  16. Amino Acid Prodrugs: An Approach to Improve the Absorption of HIV-1 Protease Inhibitor, Lopinavir

    Directory of Open Access Journals (Sweden)

    Mitesh Patel

    2014-04-01

    Full Text Available Poor systemic concentrations of lopinavir (LPV following oral administration occur due to high cellular efflux by P-glycoprotein (P-gp and multidrug resistance-associated proteins (MRPs and extensive metabolism by CYP3A4 enzymes. In this study, amino acid prodrugs of LPV were designed and investigated for their potential to circumvent efflux processes and first pass effects. Three amino acid prodrugs were synthesized by conjugating isoleucine, tryptophan and methionine to LPV. Prodrug formation was confirmed by the LCMS/MS and NMR technique. Interaction of LPV prodrugs with efflux proteins were carried out in P-gp (MDCK-MDR1 and MRP2 (MDCK-MRP2 transfected cells. Aqueous solubility studies demonstrated that prodrugs generate higher solubility relative to LPV. Prodrugs displayed higher stability under acidic conditions and degraded significantly with rise in pH. Uptake and transport data suggested that prodrugs carry significantly lower affinity towards P-gp and MRP2 relative to LPV. Moreover, prodrugs exhibited higher liver microsomal stability relative to LPV. Hence, amino acid prodrug modification might be a viable approach for enhancing LPV absorption across intestinal epithelial and brain endothelial cells which expresses high levels of P-gp and MRP2.

  17. Bolus ingestion of individual branched-chain amino acids alters plasma amino acid profiles in young healthy men

    OpenAIRE

    Matsumoto, Takuya; Nakamura, Koichi; Matsumoto, Hideki; Sakai, Ryosei; Kuwahara, Tomomi; Kadota, Yoshihiro; Kitaura, Yasuyuki; SATO, JUICHI; Shimomura, Yoshiharu

    2014-01-01

    Physiological conditions in humans affect plasma amino acid profiles that might have potential for medical use. Because the branched-chain amino acids (BCAAs) leucine, isoleucine and valine are used as medicines and supplements, we investigated the acute effects of individual BCAAs (10–90 mg/kg body weight) or mixed BCAAs ingested as a bolus on plasma amino acid profiles in young healthy men. Plasma leucine levels rapidly increased and peaked around 30 min after leucine ingestion. Concentrati...

  18. Transport system

    NARCIS (Netherlands)

    Drenth, K.F.

    1999-01-01

    The transport system comprises at least one road surface (2) and at least one vehicle (4) on wheels (6). The road surface (2) has a substantially bowl-shaped cross section and the vehicle (4) is designed so that the wheels (6) run directly on the road surface (2) while the road surface (2) acts as a

  19. Photoinduced conductivity in mycosporine-like amino acids

    Energy Technology Data Exchange (ETDEWEB)

    Kulkarni, Atul; Lee, Jeong Hun; Seo, Hyo Hyun; Kim, Hyoung-Shik; Cho, Moon Jin; Shin, Dong Sun [Antiaging Research Institute of BIO-FD and C Co. Ltd., Incheon 406-840 (Korea, Republic of); Kim, Taesung [Sungkyunkwan Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Moh, Sang Hyun, E-mail: shmoh@biofdnc.com [Antiaging Research Institute of BIO-FD and C Co. Ltd., Incheon 406-840 (Korea, Republic of)

    2015-02-01

    Mycosporine-like amino acids (MAAs) are an important group of novel bioactive compounds having immense biotechnological potentials due to their UV screening properties and antioxidant activities. However, their photoelectric properties were not evaluated yet. In the present work two types of MAAs Shinorine and Porphyra-334, were extracted from algae; Chlamydomonas hedlyei and Porphyra yezoensis respectively and its electrical transport properties were investigated upon illumination of UV light. The combination of optical absorption and electron transport measurement of MAAs in a field effect transistor device reveals that these changes are mainly due to the carboxyl group present in MAAs. This study reports a platform technology for the development of novel biochemical–electrical devices. - Highlights: • MAAs FET shows photoelectric effect upon UV illumination. • Enhancement in photo conductance is due to the hydroxyl ethyl group. • Potential as bio-opto-electrical devices applications.

  20. EFFECT OF MICROORGANISMS ON FREE AMINO ACID AND FREE D-AMINO ACID CONTENTS OF VARIOUS DAIRY PRODUCTS

    Directory of Open Access Journals (Sweden)

    Csilla Albert

    2007-06-01

    Full Text Available Free amino acid and free D-amino acid contents of milk samples with different microorganism numbers and composition of dairy products produced from them were examined. Total microorganism number of milk samples examined varied from 1.25x106 to 2.95x106. It was established that concentration of both free D-amino acids and free L-amino acids increased with an increase in microorganism number. However, increase in D-amino acid contents was higher considering its proportion. There was a particularly significant growth in the microorganism number range from 1.5x106 to 2.9x106. Based on analysis of curds and cheese samples produced using different technologies we have come to the conclusion that for fresh dairy products and for those matured over a short time there was a close relation between total microorganism number and free D-amino acid and free L-amino acid contents. At the same time it was found that the ratio of the enantiomers was not affected by the total microorganism number. For dairy products, however, where amino acid production capability of the microbial cultures considerably exceeds, production of microorganisms originally present in the milk raw material, free amino acid contents of the milk product (both D- and L-enantiomers seem to be independent of the composition of milk raw material.

  1. Capillary electrophoresis of FITC labeled amino acids with laser-induced fluorescence detection

    Institute of Scientific and Technical Information of China (English)

    党福全; 陈义

    1999-01-01

    FITC labeled amino acids have been separated using a home-huilt capillary electrophoresis with a laserinduced fluorescence detection (CE-LIF) system. Seventeen peaks can now be generated from the twenty common amino acids. The key conditions lie in the optimization of pH, buffer electrolytes and buffer additives.

  2. Optimisation of a system for the co-translational incorporation of a keto amino acid and its application to a tumour-specific Anticalin.

    Science.gov (United States)

    Reichert, Andreas J; Poxleitner, Gabriele; Dauner, Martin; Skerra, Arne

    2015-12-01

    The bioorthogonal keto group has attracted interest for the site-specific chemical conjugation of recombinant proteins under mild conditions, e.g. with aminooxy-functionalised fluorescent probes, radiometal chelates, toxins or polymers. However, the cotranslational incorporation of the corresponding non-canonical amino acid p-acetyl-L-phenylalanine (Apa) into proteins expressed in Escherichia coli by means of amber suppression using a previously described system with a mutated tRNA and an engineered tyrosyl-tRNA synthetase from Methanococcus jannaschii shows limited efficiency and considerable promiscuity towards endogenous amino acids. Employing a one-plasmid system that encodes all three components required for selection, i.e. the modified aminoacyl-tRNA synthetase (aaRS), the cognate amber suppressor tRNA and the enhanced green fluorescent protein equipped with an amber stop codon and serving as reporter, we have generated an Apa-specific aaRS&tRNA pair with considerably improved efficiency (17-fold increased expression) and also fidelity (6-fold). To this end, both the aaRS and the tRNA were subjected to doped random mutagenesis and selection in altogether four evolutionary cycles using fluorescence-activated bacterial cell sorting as well as automated screening of microcultures. The resulting aaRS&tRNA pair was applied to the functionalisation of an Anticalin with specificity towards oncofetal fibronectin by introducing a keto group at a permissible site for subsequent conjugation with a fluorescent dye, thus allowing visualisation of this tumour target under the microscope.

  3. Amino acid adsorption on mesoporous materials: influence of types of amino acids, modification of mesoporous materials, and solution conditions.

    Science.gov (United States)

    Gao, Qiang; Xu, Wujun; Xu, Yao; Wu, Dong; Sun, Yuhan; Deng, Feng; Shen, Wanling

    2008-02-21

    In order to disclose the dominant interfacial interaction between amino acids and ordered mesoporous materials, the adsorption behaviors of five amino acids on four mesoporous materials were investigated in aqueous solutions with adjustable amino acid concentration, ion strength, and pH. The selected amino acids were acidic amino acid glutamic acid (Glu), basic amino acid arginine (Arg), and neutral amino acids phenylalanine (Phe), leucine (Leu), and alanine (Ala), and the selected mesoporous materials were SBA-15, Al-SBA-15, CH3(10%)-SBA-15, and CH3(20%)-SBA-15. The adsorption capacities of Glu and Arg were strongly dependent on pH and surface charge of the mesoporous adsorbent. The adsorption of Phe showed pH insensitivity but depended on the surface organic functionalization of mesoporous adsorbent. On the basis of the theoretical analysis about the interaction between amino acid and adsorbent, such a remarkable difference was attributed to the different nature of the interaction between amino acid and adsorbent. Arg could be readily adsorbed on the surface of SBA-15, especially Al-SBA-15, under appropriate pH in which the electrostatic interaction was predominant. The driving force of Phe adsorption on mesoporous adsorbent mainly came from the hydrophobic interaction. Therefore, the adsorption capability of Arg decreased with increasing ion strength of solution, while the adsorption capability of Phe increased with the increasing degree of CH3 functionalization on SBA-15. For neutral amino acid Phe, Ala, and Leu, the adsorption capability increased with the increase of the length of their side chains, which was another evidence of hydrophobic effect. Thus, all the adsorption of amino acids on mesoporous silica materials can be decided by the combined influence of two fundamental interactions: electrostatic attraction and hydrophobic effect.

  4. Synthesis and evaluation of 2-amino-5-(4-[18F]fluorophenyl)pent-4-ynoic acid ([18F]FPhPA): A novel 18F-labeled amino acid for oncologic PET imaging

    International Nuclear Information System (INIS)

    Introduction: 18 F-labeled amino acids are important PET radiotracers for molecular imaging of cancer. This study describes synthesis and radiopharmacological evaluation of 2-amino-5-(4-[18 F]fluorophenyl)pent-4-ynoic acid ([18 F]FPhPA) as a novel amino acid radiotracer for oncologic imaging. Methods: 18 F]FPhPA was prepared using Pd-mediated SONOGASHIRA cross-coupling reaction between 4-[18 F]fluoroiodobenzene ([18 F]FIB) and propargylglycine. The radiopharmacological profile of [18 F]FPhPA was evaluated in comparison with O-(2-[18 F]fluoroethyl)-L-tyrosine ([18 F]FET) using the murine breast cancer cell line EMT6 involving cellular uptake studies, radiotracer uptake competitive inhibition experiments and small animal PET imaging. Results: 18 F]FPhPA was prepared in 42 ± 10% decay-corrected radiochemical yield with high radiochemical purity >95% after semi-preparative HPLC purification. Cellular uptake of L-[18 F]FPhPA reached a maximum of 58 ± 14 % radioactivity/mg protein at 90 min. Lower uptake was observed for racemic and D-[18 F]FPhPA. Radiotracer uptake inhibition studies by synthetic and naturally occurring amino acids suggested that Na+-dependent system ASC, especially ASCT2, and Na+-independent system L are important amino acid transporters for [18 F]FPhPA uptake into EMT6 cells. Small animal PET studies demonstrated similar high tumor uptake of [18 F]FPhPA in EMT6 tumor-bearing mice compared to [18 F]FET reaching a maximum standardized uptake value (SUV) of 1.35 after 60 min p.i.. Muscle uptake of [18 F]FPhPA was higher (SUV30min = 0.65) compared to [18 F]FET (SUV30min = 0.40), whereas [18 F]FPhPA showed a more rapid uptake and clearance from the brain compared to [18 F]FET. Conclusion: L-[18 F]FPhPA is the first 18 F-labeled amino acid prepared through Pd-mediated cross-coupling reaction. Advances in Knowledge and Implications for patient Care: L-[18 F]FPhPA displayed promising properties as a novel amino acid radiotracer for molecular imaging of

  5. Soybean toxin (SBTX impairs fungal growth by interfering with molecular transport, carbohydrate/amino acid metabolism and drug/stress responses.

    Directory of Open Access Journals (Sweden)

    Janne K S Morais

    Full Text Available Soybean toxin (SBTX is an antifungal protein from soybeans with broad inhibitory activity against the growth and filamentation of many fungi, including human and plant pathogenic species such as Candida albicans, Candida parapsilosis, Aspergillus niger, Penicillium herquei, Cercospora sojina and Cercospora kikuchii. Understanding the mechanism by which SBTX acts on fungi and yeasts may contribute to the design of novel antifungal drugs and/or the development of transgenic plants resistant to pathogens. To this end, the polymorphic yeast C. albicans was chosen as a model organism and changes in the gene expression profile of strain SC5314 upon exposure to SBTX were examined. Genes that were differentially regulated in the presence of SBTX were involved in glucose transport and starvation-associated stress responses as well as in the control of both the induction and repression of C. albicans hyphal formation. Transmission electron microscopy showed that C. albicans cells exposed to SBTX displayed severe signs of starvation and were heavily granulated. Our data were indicative of C. albicans cell starvation despite sufficient nutrient availability in the medium; therefore, it can be speculated that SBTX blocks nutrient uptake systems. Because neither the starvation signal nor the alkaline response pathway lead to the induction of hyphae, we hypothesise that conflicting signals are transmitted to the complex regulatory network controlling morphogenesis, eventually preventing the filamentation signal from reaching a significant threshold.

  6. Soybean toxin (SBTX) impairs fungal growth by interfering with molecular transport, carbohydrate/amino acid metabolism and drug/stress responses.

    Science.gov (United States)

    Morais, Janne K S; Bader, Oliver; Weig, Michael; Oliveira, Jose Tadeu A; Arantes, Mariana R; Gomes, Valdirene M; Da Cunha, Maura; Oliveira, Hermogenes D; Sousa, Daniele O B; Lourencao, Andre L; Vasconcelos, Ilka M

    2013-01-01

    Soybean toxin (SBTX) is an antifungal protein from soybeans with broad inhibitory activity against the growth and filamentation of many fungi, including human and plant pathogenic species such as Candida albicans, Candida parapsilosis, Aspergillus niger, Penicillium herquei, Cercospora sojina and Cercospora kikuchii. Understanding the mechanism by which SBTX acts on fungi and yeasts may contribute to the design of novel antifungal drugs and/or the development of transgenic plants resistant to pathogens. To this end, the polymorphic yeast C. albicans was chosen as a model organism and changes in the gene expression profile of strain SC5314 upon exposure to SBTX were examined. Genes that were differentially regulated in the presence of SBTX were involved in glucose transport and starvation-associated stress responses as well as in the control of both the induction and repression of C. albicans hyphal formation. Transmission electron microscopy showed that C. albicans cells exposed to SBTX displayed severe signs of starvation and were heavily granulated. Our data were indicative of C. albicans cell starvation despite sufficient nutrient availability in the medium; therefore, it can be speculated that SBTX blocks nutrient uptake systems. Because neither the starvation signal nor the alkaline response pathway lead to the induction of hyphae, we hypothesise that conflicting signals are transmitted to the complex regulatory network controlling morphogenesis, eventually preventing the filamentation signal from reaching a significant threshold.

  7. The Path of Carbon in Photosynthesis II. Amino Acids

    Science.gov (United States)

    Stepka, W.; Benson, A. A.; Calvin, M.

    1948-05-25

    The radioactive amino acid's synthesized from C{sup 14}O{sub 2} by green algae both in the light and in the dark after CO{sub 2}-free preillumination have been separated and identified using paper chromatography and radioautography. The radioactive amino acids identified were aspartic acid, alanine and smaller amounts of 3- and 4-carbon amino acids. This finding as well as the total absence of radioactive glutamic acid substantiates the mechanism for reduction of CO{sub 2} previously postulated by members of this laboratory.

  8. Uptake of sialic acid by human erythrocyte. Characterization of a transport system.

    Science.gov (United States)

    Bulai, Tatiana; Bratosin, Daniela; Artenie, Vlad; Montreuil, Jean

    2003-01-01

    Upon incubation of human red blood cells (RBC) with [4-9-14C] N-acetylneuraminic acid, the cells incorporated this sugar, as demonstrated by the identification of labelled N-acetylmannosamine in the cytosol, as a result of the action of the sialic acid pyruvate-lyase we discovered previously (Biochimie 84 (2002) 655). The mechanism is saturable and indicates the presence of a limited number of transporter molecules in the RBC membrane. This transport process may have relevance to the desialylation of membrane glycoconjugates which occurs during ageing of erythrocytes.

  9. 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...

  10. Improvement of pea biomass and seed productivity by simultaneous increase of phloem and embryo loading with amino acids.

    Science.gov (United States)

    Zhang, Lizhi; Garneau, Matthew G; Majumdar, Rajtilak; Grant, Jan; Tegeder, Mechthild

    2015-01-01

    The development of sink organs such as fruits and seeds strongly depends on the amount of nitrogen that is moved within the phloem from photosynthetic-active source leaves to the reproductive sinks. In many plant species nitrogen is transported as amino acids. In pea (Pisum sativum L.), source to sink partitioning of amino acids requires at least two active transport events mediated by plasma membrane-localized proteins, and these are: (i) amino acid phloem loading; and (ii) import of amino acids into the seed cotyledons via epidermal transfer cells. As each of these transport steps might potentially be limiting to efficient nitrogen delivery to the pea embryo, we manipulated both simultaneously. Additional copies of the pea amino acid permease PsAAP1 were introduced into the pea genome and expression of the transporter was targeted to the sieve element-companion cell complexes of the leaf phloem and to the epidermis of the seed cotyledons. The transgenic pea plants showed increased phloem loading and embryo loading of amino acids resulting in improved long distance transport of nitrogen, sink development and seed protein accumulation. Analyses of root and leaf tissues further revealed that genetic manipulation positively affected root nitrogen uptake, as well as primary source and sink metabolism. Overall, the results suggest that amino acid phloem loading exerts regulatory control over pea biomass production and seed yield, and that import of amino acids into the cotyledons limits seed protein levels.

  11. Amino Acid and Peptide Immobilization on Oxidized Nanocellulose: Spectroscopic Characterization

    OpenAIRE

    Claude Daneault; Saïd Barazzouk

    2012-01-01

    In this work, oxidized nanocellulose (ONC) was synthesized and chemically coupled with amino acids and peptides using a two step coupling method at room temperature. First, ONC was activated by N-ethyl-N’-(3-dimethylaminopropyl) carbodiimide hydrochloride, forming a stable active ester in the presence of N-hydroxysuccinimide. Second, the active ester was reacted with the amino group of the amino acid or peptide, forming an amide bond between ONC and the grafted molecule. Using this method, th...

  12. Hydration of protonated aromatic amino acids: phenylalanine, tryptophan, and tyrosine.

    Science.gov (United States)

    Gao, Bing; Wyttenbach, Thomas; Bowers, Michael T

    2009-04-01

    The first steps of hydration of the protonated aromatic amino acids phenylalanine, tryptophan, and tyrosine were studied experimentally employing a mass spectrometer equipped with a drift cell to examine the sequential addition of individual water molecules in equilibrium experiments and theoretically by a combination of molecular mechanics and electronic structure calculations (B3LYP/6-311++G**) on the three amino acid systems including up to five water molecules. It is found that both the ammonium and carboxyl groups offer good water binding sites with binding energies of the order of 13 kcal/mol for the first water molecule. Subsequent water molecules bind less strongly, in the range of 7-11 kcal/mol for the second through fifth water molecules. The ammonium group is able to host up to three water molecules and the carboxyl group one water molecule before additional water molecules bind either to the amino acid side chain as in tyrosine or to already-bound water in a second solvation shell around the ammonium group. Reasons for the surprisingly high water affinity of the neutral carboxyl group, comparable to that of the charge-carrying ammonium group, are found to be high intrinsic hydrophilicity, favorable charge-dipole alignment, and--for the case of multiply hydrated species--favorable dipole-dipole interaction among water molecules and the lack of alternative fully exposed hydration sites.

  13. Phase Chemistry of the Complexes of RE Amino Acids

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Forty-three phase diagrams of ternary system concerning rare earth salts, α-amino acids and water, which were constructed by phase equilibrium methods, were expounded. The influences of the factors such as cations, anions, the structure of amino acids, temperature on the phase diagrams were discussed. Under the guidance of phase equilibrium results, over 150 new solid complexes were prepared. IR, reflecting, UV, FS, and Raman spectra for these complexes were investigated and the regularity of “tripartite effect”, “tetrad effect”, “Nephelanxetic effect”, “Oddo-Harkins” was observed. Thermal decomposition processes of the complexes were confirmed. Based on the comparison with the known crystal structures of rare earth-amino acid-complexes, an estimation method for predicting the crystal structure data of series complexes was founded. The constant volume combustion energies of the complexes were determined by RBC-1 type rotating bomb calorimeter. The standard enthalpies of combustion and standard enthalpies of formation were calculated for these complexes.

  14. Proteins, Peptides and Amino Acids: Role in Infant Nutrition.

    Science.gov (United States)

    Nutten, Sophie

    2016-01-01

    Proteins are polymers composed of 30 or more amino acids; some of them are essential dietary components, since they are not synthetized by human metabolic processes. They are crucial for healthy growth and development and influence major functions of the body. The infant's first year is a critical time of rapid growth and development, which must be supported by a high rate of protein synthesis. Breast milk, as a single specific food source in the first months of life, is providing the total protein and essential amino acids required. Infant formulas have been designed for infants who cannot be breastfed. They should be similar to breast milk in their composition and their functional outcomes, insuring appropriate growth, optimal development, maturation of the immune system, easy digestion and healthy metabolic programming. By modifying their protein components, specific infant formulas have also been developed for specific needs. For example, partially hydrolyzed (prevention of atopic dermatitis) and extensively hydrolyzed or amino-acid-based infant formulas (reduction in allergy symptoms) have been designed for the management of cow's milk protein allergy. In conclusion, proteins provided via breast milk or infant formula are essential components of the infant's diet; therefore, the specific quality, quantity and conformation of proteins are of utmost importance for healthy growth and development.

  15. Proteins, Peptides and Amino Acids: Role in Infant Nutrition.

    Science.gov (United States)

    Nutten, Sophie

    2016-01-01

    Proteins are polymers composed of 30 or more amino acids; some of them are essential dietary components, since they are not synthetized by human metabolic processes. They are crucial for healthy growth and development and influence major functions of the body. The infant's first year is a critical time of rapid growth and development, which must be supported by a high rate of protein synthesis. Breast milk, as a single specific food source in the first months of life, is providing the total protein and essential amino acids required. Infant formulas have been designed for infants who cannot be breastfed. They should be similar to breast milk in their composition and their functional outcomes, insuring appropriate growth, optimal development, maturation of the immune system, easy digestion and healthy metabolic programming. By modifying their protein components, specific infant formulas have also been developed for specific needs. For example, partially hydrolyzed (prevention of atopic dermatitis) and extensively hydrolyzed or amino-acid-based infant formulas (reduction in allergy symptoms) have been designed for the management of cow's milk protein allergy. In conclusion, proteins provided via breast milk or infant formula are essential components of the infant's diet; therefore, the specific quality, quantity and conformation of proteins are of utmost importance for healthy growth and development. PMID:27336588

  16. Separation of amino acid enantiomers by micelle-enhanced ultrafiltration

    NARCIS (Netherlands)

    Bruin, de T.J.M.; Marcelis, A.T.M.; Zuilhof, H.; Rodenburg, L.M.; Overdevest, P.E.M.; Padt, van der A.; Sudhölter, E.J.R.

    2000-01-01

    A Micelle-enhanced ultrafiltration (MEUF) separation process was investigated that can potentially be used for large-scale enantioseparations. Copper(II)-amino acid derivatives dissolved in nonionic surfactant micelles were used as chiral selectors for the separation of dilute racemic amino acids so

  17. Interactive Hangman Teaches Amino Acid Structures and Abbreviations

    Science.gov (United States)

    Pennington, Britney O.; Sears, Duane; Clegg, Dennis O.

    2014-01-01

    We developed an interactive exercise to teach students how to draw the structures of the 20 standard amino acids and to identify the one-letter abbreviations by modifying the familiar game of "Hangman." Amino acid structures were used to represent single letters throughout the game. To provide additional practice in identifying…

  18. Ant Colony Approach to Predict Amino Acid Interaction Networks

    OpenAIRE

    Gaci, Omar; Balev, Stefan

    2009-01-01

    In this paper we introduce the notion of protein interaction network. This is a graph whose vertices are the proteins amino acids and whose edges are the interactions between them. We consider the problem of reconstructing protein's interaction network from its amino acid sequence. An ant colony approach is used to solve this problem.

  19. Physiological and biochemical studies of bacterial amino acid amide metabolism

    NARCIS (Netherlands)

    Hermes, Hubertus Franciscus Maria

    2008-01-01

    Amino acids represent a class of versatile chiral building blocks for a whole range of fine chemicals, used in the pharmaceutical and agro-chemical industry. Considerable experience currently is available with a wide variety of chemo-enzymatic processes for the synthesis of amino acids, which is app

  20. Natural toxins that affect plant amino acid metabolism

    Science.gov (United States)

    A diverse range of natural compounds interfere with the synthesis and other aspects of amino acid metabolism. Some are amino acid analogues, but most are not. This review covers a number of specific natural phytotoxic compounds by molecular target site. Inhibition of glutamine synthetase is of part...

  1. CO2 sorption by supported amino acid ionic liquids

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention concerns the absorption and desorption behaviour of carbon dioxide (CO2) using ionic liquids derived from amino acids adsorbed on porous carrier materials.......The present invention concerns the absorption and desorption behaviour of carbon dioxide (CO2) using ionic liquids derived from amino acids adsorbed on porous carrier materials....

  2. Site specific incorporation of keto amino acids into proteins

    Science.gov (United States)

    Schultz, Peter G.; Wang, Lei

    2011-03-22

    Compositions and methods of producing components of protein biosynthetic machinery that include orthogonal tRNAs, orthogonal aminoacyl-tRNA synthetases, and orthogonal pairs of tRNAs/synthetases, which incorporate keto amino acids into proteins are provided. Methods for identifying these orthogonal pairs are also provided along with methods of producing proteins with keto amino acids using these orthogonal pairs.

  3. Meteoritic Amino Acids: Diversity in Compositions Reflects Parent Body Histories.

    Science.gov (United States)

    Elsila, Jamie E; Aponte, José C; Blackmond, Donna G; Burton, Aaron S; Dworkin, Jason P; Glavin, Daniel P

    2016-06-22

    The analysis of amino acids in meteorites dates back over 50 years; however, it is only in recent years that research has expanded beyond investigations of a narrow set of meteorite groups (exemplified by the Murchison meteorite) into meteorites of other types and classes. These new studies have shown a wide diversity in the abundance and distribution of amino acids across carbonaceous chondrite groups, highlighting the role of parent body processes and composition in the creation, preservation, or alteration of amino acids. Although most chiral amino acids are racemic in meteorites, the enantiomeric distribution of some amino acids, particularly of the nonprotein amino acid isovaline, has also been shown to vary both within certain meteorites and across carbonaceous meteorite groups. Large l-enantiomeric excesses of some extraterrestrial protein amino acids (up to ∼60%) have also been observed in rare cases and point to nonbiological enantiomeric enrichment processes prior to the emergence of life. In this Outlook, we review these recent meteoritic analyses, focusing on variations in abundance, structural distributions, and enantiomeric distributions of amino acids and discussing possible explanations for these observations and the potential for future work. PMID:27413780

  4. The protein digestibility-corrected amino acid score

    NARCIS (Netherlands)

    Schaafsma, G.

    2000-01-01

    The protein digestibility–corrected amino acid score (PDCAAS) has been adopted by FAO/WHO as the preferred method for the measurement of the protein value in human nutrition. The method is based on comparison of the concentration of the first limiting essential amino acid in the test protein with th

  5. Nitrogen and amino acid metabolism in dairy cows

    NARCIS (Netherlands)

    Tamminga, S.

    1981-01-01

    For the process of milk production, the dairy cow requires nutrients of which energy supplying nutrients and protein or amino acid supplying nutrients are the most important. Amino acid supplying nutrients have to be absorbed from the small intestine and the research reported in this thesis mainly c

  6. Recommended ingestion of indispensable amino acids to young men . A study using stable isotopes, plasmatic amino acids and nitrogen balance

    International Nuclear Information System (INIS)

    It has been previously stated that the minimum physiological recommendations for the indispensable amino acids in health adults, as proposed by FAO/WHO/UNU in 1985, are far too low, except for the methionine. An amino acid stable isotopic kinetic study was conducted to seek further experimental support to this hypothesis. Twenty healthy young men received an l-amino acid based diet, supplying 140 mg N.kg-1.d-1, patterned on egg protein for 1 week, then for 3 weeks either i) a pattern based on current international recommendations (FAO diet, n=7), ii) a the tentative Laboratory of Human Nutrition of the Massachusetts Institute of Technology, new amino acid recommendation pattern (MIT diet, n=7) or iii) again the egg hen pattern (EGG diet, n=6). All subjects were again studied for one final, consecutive week of the egg diet. At the end of the initial week, at the first and third week with the three experimental diets,and after three days following the return of the egg diet, an 8 h primed continuous intravenous infusion with l-13 C-leucine was conducted (3 h, fast, 5 h fed - while subjects received hourly meals supplying the equivalent of 5/12 total daily intake). Estimation of leucine balance were carried out with measurements plasma free amino acids changes. Daily nitrogen balances were obtained through the study. Interpretation of plasma amino acids profile, and changes of leucine kinetics balances, indicated that the FAO diet was not able to maintain amino acids homeostasis whereas the MIT and the egg diets sustained body amino acids equilibrium with a positive amino acid balance. nitrogen balances tended to be more negative with the FAO diet but failed to show statistically significant differences among the three diets. The finding point out that it would be prudent to use the new, tentative recommended amino acid pattern (MIT diet 0 as the minimum physiological amino acid needs of healthy human adults (author)

  7. Electronic coupling through natural amino acids

    International Nuclear Information System (INIS)

    Myriad scientific domains concern themselves with biological electron transfer (ET) events that span across vast scales of rate and efficiency through a remarkably fine-tuned integration of amino acid (AA) sequences, electronic structure, dynamics, and environment interactions. Within this intricate scheme, many questions persist as to how proteins modulate electron-tunneling properties. To help elucidate these principles, we develop a model set of peptides representing the common α-helix and β-strand motifs including all natural AAs within implicit protein-environment solvation. Using an effective Hamiltonian strategy with density functional theory, we characterize the electronic coupling through these peptides, furthermore considering side-chain dynamics. For both motifs, predictions consistently show that backbone-mediated electronic coupling is distinctly sensitive to AA type (aliphatic, polar, aromatic, negatively charged and positively charged), and to side-chain orientation. The unique properties of these residues may be employed to design activated, deactivated, or switch-like superexchange pathways. Electronic structure calculations and Green’s function analyses indicate that localized shifts in the electron density along the peptide play a role in modulating these pathways, and further substantiate the experimentally observed behavior of proline residues as superbridges. The distinct sensitivities of tunneling pathways to sequence and conformation revealed in this electronic coupling database help improve our fundamental understanding of the broad diversity of ET reactivity and provide guiding principles for peptide design

  8. Electronic coupling through natural amino acids

    Science.gov (United States)

    Berstis, Laura; Beckham, Gregg T.; Crowley, Michael F.

    2015-12-01

    Myriad scientific domains concern themselves with biological electron transfer (ET) events that span across vast scales of rate and efficiency through a remarkably fine-tuned integration of amino acid (AA) sequences, electronic structure, dynamics, and environment interactions. Within this intricate scheme, many questions persist as to how proteins modulate electron-tunneling properties. To help elucidate these principles, we develop a model set of peptides representing the common α-helix and β-strand motifs including all natural AAs within implicit protein-environment solvation. Using an effective Hamiltonian strategy with density functional theory, we characterize the electronic coupling through these peptides, furthermore considering side-chain dynamics. For both motifs, predictions consistently show that backbone-mediated electronic coupling is distinctly sensitive to AA type (aliphatic, polar, aromatic, negatively charged and positively charged), and to side-chain orientation. The unique properties of these residues may be employed to design activated, deactivated, or switch-like superexchange pathways. Electronic structure calculations and Green's function analyses indicate that localized shifts in the electron density along the peptide play a role in modulating these pathways, and further substantiate the experimentally observed behavior of proline residues as superbridges. The distinct sensitivities of tunneling pathways to sequence and conformation revealed in this electronic coupling database help improve our fundamental understanding of the broad diversity of ET reactivity and provide guiding principles for peptide design.

  9. Electronic coupling through natural amino acids

    Energy Technology Data Exchange (ETDEWEB)

    Berstis, Laura; Beckham, Gregg T., E-mail: michael.crowley@nrel.gov, E-mail: gregg.beckham@nrel.gov; Crowley, Michael F., E-mail: michael.crowley@nrel.gov, E-mail: gregg.beckham@nrel.gov [National Renewable Energy Laboratory, National Bioenergy Center, 15013 Denver West Pkwy, Golden, Colorado 80401 (United States)

    2015-12-14

    Myriad scientific domains concern themselves with biological electron transfer (ET) events that span across vast scales of rate and efficiency through a remarkably fine-tuned integration of amino acid (AA) sequences, electronic structure, dynamics, and environment interactions. Within this intricate scheme, many questions persist as to how proteins modulate electron-tunneling properties. To help elucidate these principles, we develop a model set of peptides representing the common α-helix and β-strand motifs including all natural AAs within implicit protein-environment solvation. Using an effective Hamiltonian strategy with density functional theory, we characterize the electronic coupling through these peptides, furthermore considering side-chain dynamics. For both motifs, predictions consistently show that backbone-mediated electronic coupling is distinctly sensitive to AA type (aliphatic, polar, aromatic, negatively charged and positively charged), and to side-chain orientation. The unique properties of these residues may be employed to design activated, deactivated, or switch-like superexchange pathways. Electronic structure calculations and Green’s function analyses indicate that localized shifts in the electron density along the peptide play a role in modulating these pathways, and further substantiate the experimentally observed behavior of proline residues as superbridges. The distinct sensitivities of tunneling pathways to sequence and conformation revealed in this electronic coupling database help improve our fundamental understanding of the broad diversity of ET reactivity and provide guiding principles for peptide design.

  10. Functional amino acids in nutrition and health.

    Science.gov (United States)

    Wu, Guoyao

    2013-09-01

    The recent years have witnessed growing interest in biochemistry, physiology and nutrition of amino acids (AA) in growth, health and disease of humans and other animals. This results from the discoveries of AA in cell signaling involving protein kinases, G protein-coupled receptors, and gaseous molecules (i.e., NO, CO and H2S). In addition, nutritional studies have shown that dietary supplementation with several AA (e.g., arginine, glutamine, glutamate, leucine, and proline) modulates gene expression, enhances growth of the small intestine and skeletal muscle, or reduces excessive body fat. These seminal findings led to the new concept of functional AA, which are defined as those AA that participate in and regulate key metabolic pathways to improve health, survival, growth, development, lactation, and reproduction of the organisms. Functional AA hold great promise in prevention and treatment of metabolic diseases (e.g., obesity, diabetes, and cardiovascular disorders), intrauterine growth restriction, infertility, intestinal and neurological dysfunction, and infectious disease (including viral infections).

  11. Uptake of neutral alpha- and beta-amino acids by human proximal tubular cells

    DEFF Research Database (Denmark)

    Jessen, H; Røigaard, H; Jacobsen, Christian

    1996-01-01

    relatively low. Nor did L-arginine and L-aspartic acid affect the uptake of beta-alanine into AHKE cells. Comparison with the results obtained for normal (NHKE) and immortalized (IHKE) embryonic cells suggested an unaltered expression of the types of transport carriers for neutral alpha- and beta-amino acids...

  12. Incretin effect after oral amino Acid ingestion in humans

    DEFF Research Database (Denmark)

    Lindgren, Ola; Pacini, Giovanni; Tura, Andrea;

    2015-01-01

    is also present after amino acid ingestion is not known. OBJECTIVE: The objective of the study was to explore insulin secretion and incretin hormones after oral and iv amino acid administration at matched total amino acid concentrations in healthy subjects. DESIGN: An amino acid mixture (Vaminolac......CONTEXT: The incretin effect is the augmented insulin secretion by oral vs iv glucose at matching glucose levels. We previously demonstrated an augmented insulin secretion when fat is given orally rather than iv, suggesting an incretin effect also after fat. However, whether an incretin effect......) was administered orally or iv at a rate resulting in matching total amino acid concentrations to 12 male volunteers with age 22.5 ± 1.4 years and a body mass index 22.4 ± 1.4 kg/m(2), who had no history of diabetes. MAIN OUTCOME MEASURES: Main outcome measures were area under the 120-minute curve for insulin, C...

  13. Stardust, Supernovae and the Chirality of the Amino Acids

    Energy Technology Data Exchange (ETDEWEB)

    Boyd, R N; Kajino, T; Onaka, T

    2011-03-09

    A mechanism for creating enantiomerism in the amino acids, the building blocks of the proteins, that involves global selection of one chirality by interactions between the amino acids and neutrinos from core-collapse supernovae is described. The selection involves the dependence of the interaction cross sections on the orientations of the spins of the neutrinos and the 14N nuclei in the amino acids, or in precursor molecules, which in turn couple to the molecular chirality. The subsequent chemical evolution and galactic mixing would ultimately populate the Galaxy with the selected species. The resulting amino acids could either be the source thereof on Earth, or could have triggered the chirality that was ultimately achieved for Earth's amino acids.

  14. Adaptive amino acid composition in collagens of parasitic nematodes.

    Science.gov (United States)

    Hughes, Austin L

    2015-04-01

    Amino acid composition was analyzed in the glycine-rich repeat region of 306 collagens belonging to three major families of collagens from both parasitic and free-living nematodes. The collagens of parasitic species showed a tendency toward decreased usage of the hydrophilic residues A, D, and Q and increased usage of the hydrophobic resides I, L, and M; and this trend was seen in parasitic species of both the order Rhabdita and the order Spirurida. The amino acid composition of collagens of parasitic Rhabdita thus tended to resemble those of Spirurida more than that of free-living Rhabdita, suggesting an association between amino acid composition and a parasitic lifestyle. Computer predictions suggested that the more hydrophobic amino acid composition was associated with a reduction of the propensity towards B-cell epitope formation, suggesting that evasion of host immune responses may be a major selective factor responsible for the parasite-specific trend in collagen amino acid composition.

  15. Supernovae, Neutrinos and the Chirality of Amino Acids

    Directory of Open Access Journals (Sweden)

    Toshitaka Kajino

    2011-05-01

    Full Text Available A mechanism for creating an enantioenrichment in the amino acids, the building blocks of the proteins, that involves global selection of one handedness by interactions between the amino acids and neutrinos from core-collapse supernovae is defined. The chiral selection involves the dependence of the interaction cross sections on the orientations of the spins of the neutrinos and the 14N nuclei in the amino acids, or in precursor molecules, which in turn couple to the molecular chirality. It also requires an asymmetric distribution of neutrinos emitted from the supernova. The subsequent chemical evolution and galactic mixing would ultimately populate the Galaxy with the selected species. The resulting amino acids could either be the source thereof on Earth, or could have triggered the chirality that was ultimately achieved for Earth’s proteinaceous amino acids.

  16. Supernovae, Neutrinos, and the Chirality of the Amino Acids

    CERN Document Server

    Boyd, R N; Onaka, T

    2011-01-01

    A mechanism for creating an enantioenrichment in the amino acids, the building blocks of the proteins, that involves global selection of one handedness by interactions between the amino acids and neutrinos from core-collapse supernovae is described. The chiral selection involves the dependence of the interaction cross sections on the orientations of the spins of the neutrinos and the 14N nuclei in the amino acids, or in precursor molecules, which in turn couple to the molecular chirality. It also requires an asymmetric distribution of neutrinos emitted from the supernova. The subsequent chemical evolution and galactic mixing would ultimately populate the Galaxy with the selected species. The resulting amino acids could either be the source thereof on Earth, or could have triggered the chirality that was ultimately achieved for Earth's proteinaceous amino acids.

  17. Amino acids and osmolarity in honeybee drone haemolymph.

    Science.gov (United States)

    Leonhard, B; Crailsheim, K

    1999-01-01

    In the haemolymph of honeybee drones, concentrations of free amino acids were higher than in worker haemolymph, with different relative proportions of individual amino acids. The overall concentration of free amino acids reached its highest level at the 5th day after adult drone emergence, and after the 9th day only minor changes in the concentration and distribution of free amino acids were observed. This coincides with the age when drones reach sexual maturity and change their feeding behaviour. Levels of essential free amino acids were high during the first 3 days of life and thereafter decreased. Osmolarity was lowest at emergence (334 +/- 42 mOsm), increased until the age of 3 days (423 +/- 32 mOsm) and then stayed generally constant until the 16th day of life. Only 25-day-old drones had significantly higher osmolarity (532 +/- 38 mOsm). The overall change in osmolarity during a drone's lifetime was about 40%. PMID:10524277

  18. Independence divergence-generated binary trees of amino acids.

    Science.gov (United States)

    Tusnády, G E; Tusnády, G; Simon, I

    1995-05-01

    The discovery of the relationship between amino acids is important in terms of the replacement ability, as used in protein engineering homology studies, and gaining a better understanding of the roles which various properties of the residues play in the creation of a unique, stable, 3-D protein structure. Amino acid sequences of proteins edited by evolution are anything but random. The measure of nonrandomness, i.e. the level of editing, can be characterized by an independence divergence value. This parameter is used to generate binary tree relationships between amino acids. The relationships of residues presented in this paper are based on protein building features and not on the physico-chemical characteristics of amino acids. This approach is not biased by the tautology present in all sequence similarity-based relationship studies. The roles which various physico-chemical characteristics play in the determination of the relationships between amino acids are also discussed.

  19. Elevated amniotic fluid amino acid levels in fetuses with gastroschisis

    Directory of Open Access Journals (Sweden)

    A. Kale

    2006-08-01

    Full Text Available Our objective was to measure maternal plasma and amniotic fluid amino acid concentrations in pregnant women diagnosed as having fetuses with gastroschisis in the second trimester of pregnancy. Twenty-one pregnant women who had fetuses with gastroschisis detected by ultrasonography (gastroschisis group in the second trimester and 32 women who had abnormal triple screenings indicating an increased risk for Down syndrome but had healthy fetuses (control group were enrolled in the study. Amniotic fluid was obtained by amniocentesis, and maternal plasma samples were taken simultaneously. The chromosomal analysis of the study and control groups was normal. Levels of free amino acids and non-essential amino acids were measured in plasma and amniotic fluid samples using EZ:fast kits (EZ:fast GC/FID free (physiological amino acid kit by gas chromatography (Focus GC AI 3000 Thermo Finnigan analyzer. The mean levels of essential amino acids (histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine and non-essential amino acids (alanine, glycine, proline, and tyrosine in amniotic fluid were found to be significantly higher in fetuses with gastroschisis than in the control group (P < 0.05. A significant positive correlation between maternal plasma and amniotic fluid concentrations of essential and nonessential amino acids was found only in the gastroschisis group (P < 0.05. The detection of significantly higher amino acid concentrations in the amniotic fluid of fetuses with a gastroschisis defect than in healthy fetuses suggests the occurrence of amino acid malabsorption or of amino acid leakage from the fetus into amniotic fluid.

  20. Hydration of amino acids: FTIR spectra and molecular dynamics studies.

    Science.gov (United States)

    Panuszko, Aneta; Adamczak, Beata; Czub, Jacek; Gojło, Emilia; Stangret, Janusz

    2015-11-01

    The hydration of selected amino acids, alanine, glycine, proline, valine, isoleucine and phenylalanine, has been studied in aqueous solutions by means of FTIR spectra of HDO isotopically diluted in H2O. The difference spectra procedure and the chemometric method have been applied to remove the contribution of bulk water and thus to separate the spectra of solute-affected HDO. To support interpretation of obtained spectral results, molecular dynamics simulations of amino acids were performed. The structural-energetic characteristic of these solute-affected water molecules shows that, on average, water affected by amino acids forms stronger and shorter H-bonds than those in pure water. Differences in the influence of amino acids on water structure have been noticed. The effect of the hydrophobic side chain of an amino acid on the solvent interactions seems to be enhanced because of the specific cooperative coupling of water strong H-bond chain, connecting the carboxyl and amino groups, with the clathrate-like H-bond network surrounding the hydrocarbon side chain. The parameter derived from the spectral data, which corresponds to the contributions of the population of weak hydrogen bonds of water molecules which have been substituted by the stronger ones in the hydration sphere of amino acids, correlated well with the amino acid hydrophobicity indexes.

  1. Portage transport of sulfanilamide and sulfanilic acid.

    Science.gov (United States)

    Hwang, S Y; Berges, D A; Taggart, J J; Gilvarg, C

    1989-03-01

    Sulfanilic acid, in contrast to sulfanilamide, has poor in vitro antibacterial activity. Paradoxically, it has been shown to be a more effective inhibitor than sulfanilamide of dihydropteroic acid synthase. In order to circumvent the presumed permeability barrier to sulfanilic acid, advantage was taken of the technique of portage transport. Derivatives of the compound were prepared in which it was linked via its primary amino group to the alpha-carbon of glycine residues in di- and tripeptides. L-Alanyl-L-alanyl-L-2-[(4-sulfophenyl)amino]glycine proved to be 207 times more potent than sulfanilic acid and 8 times more active than either sulfanilamide or L-alanyl-L-alanyl-L-2-[[4-(aminosulfonyl)-phenyl]amino]glycine when tested against Escherichia coli. These findings confirm that the weak in vitro activity of sulfanilic acid is due to its limited ability to penetrate the bacterial membrane. They also emphasize the ability of portage transport to reveal therapeutic capability that had been attenuated by poor drug permeation.

  2. Lineage-specific expansion of vomeronasal type 2 receptor-like (OlfC) genes in cichlids may contribute to diversification of amino acid detection systems.

    Science.gov (United States)

    Nikaido, Masato; Suzuki, Hikoyu; Toyoda, Atsushi; Fujiyama, Asao; Hagino-Yamagishi, Kimiko; Kocher, Thomas D; Carleton, Karen; Okada, Norihiro

    2013-01-01

    Fish use olfaction to sense a variety of nonvolatile chemical signals in water. However, the evolutionary importance of olfaction in species-rich cichlids is controversial. Here, we determined an almost complete sequence of the vomeronasal type 2 receptor-like (OlfC: putative amino acids receptor in teleosts) gene cluster using the bacterial artificial chromosome library of the Lake Victoria cichlid, Haplochromis chilotes. In the cluster region, we found 61 intact OlfC genes, which is the largest number of OlfC genes identified among the seven teleost fish investigated to date. Data mining of the Oreochromis niloticus (Nile tilapia) draft genome sequence, and genomic Southern hybridization analysis revealed that the ancestor of all modern cichlids had already developed almost the same OlfC gene repertoire, which was accomplished by lineage-specific gene expansions. Furthermore, comparison of receptor sequences showed that recently duplicated paralogs are more variable than orthologs of different species at particular sites that were predicted to be involved in amino acid selectivity. Thus, the increase of paralogs through gene expansion may lead to functional diversification in detection of amino acids. This study implies that cichlids have developed a potent capacity to detect a variety of amino acids (and their derivatives) through OlfCs, which may have contributed to the extraordinary diversity of their feeding habitats. PMID:23501830

  3. Molecular recognition on supramolecular systems (XXXV)——Synthesis of novel β-cyclodextrin derivative bearing pyridinio group and its chiral discrimination of amino acids

    Institute of Scientific and Technical Information of China (English)

    刘育; 康诗钊

    2001-01-01

    A novel p-cyclodextrin derivative 4 bearing a pyridinio group on the primary side was synthesized by the reaction of 2-aminopyridine with 6-p-cyclodextrin monoaldehyde 3, and its complexation stability constants with several aliphatic amino acids have been determined in phosphate buffer solution ( pH = 7.2, 0.1 mol ?L-1) at 25℃by using spectrofluorometric titrations. The stoichiometry is 1 : 1 for the inclusion complexation of amino acids with compound 4. Circular dichroism study indicates that the aromatic moiety was embedded shallowly into the cyclodextrin cavity. As a spectral probe, the pyridinio group in the modified cyclodextrin can recognize not only differences of the size and shape of amino acid molecules, but also the L/D-amino acid chiral iso-mer. As compared with mono-[6-(1-pyridinio)-6-deoxy]-p-cyclodextrin 5, compound 4 switched the enantiomer preference for L- to D-isomer, and showed the highest enantioselectivity of 5.4 for D/L-serine. These results are discussed from the viewpoints of ge

  4. Molecular recognition on supramolecular systems (XXXV)-- Synthesis of novel b-cyclodextrin derivative bearing pyridinio group and its chiral discrimination of amino acids

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A novel b-cyclodextrin derivative 4 bearing a pyridinio group on the primary side was synthesized by the reaction of 2-aminopyridine with 6-b-cyclodextrin monoaldehyde 3, and its complexation stability constants with several aliphatic amino acids have been determined in phosphate buffer solution ( pH = 7.2, 0.1 mol·L-1) at 25 ℃ by using spectrofluormetric titrations. The stoichiometry is 1︰1 for the inclusion complexation of amino acids with compound 4. Circular dichroism study indicates that the aromatic moiety was embedded shallowly into the cyclodextrin cavity. As a spectral probe, the pyridinio group in the modified cyclodextrin can recognize not only differences of the size and shape of amino acid molecules, but also the L/D-amino acid chiral isomer. As com-pared with mono-[6-(1-pyridinio)-6-deoxy]-b-cyclodextrin 5, compound 4 switched the enantiomer preference for L- to D-isomer, and showed the highest enantioselectivity of 5.4 for D/L-serine. The-se results are discussed from the viewpoints of geometric compensation, induced-fit concept and cooperation of several weak interactions.

  5. Effect of thenardite on the direct detection of aromatic amino acids: implications for the search for life in the solar system

    Science.gov (United States)

    Doc Richardson, C.; Hinman, Nancy W.; Scott, Jill R.

    2009-10-01

    With the discovery of Na-sulphate minerals on Mars and Europa, recent studies using these minerals have focused on their ability to assist in the detection of bio/organic signatures. This study further investigates the ability of thenardite (Na2SO4) to effectively facilitate the ionization and identification of aromatic amino acids (phenylalanine, tyrosine and tryptophan) using a technique called geomatrix-assisted laser desorption/ionization in conjunction with a Fourier transform ion cyclotron resonance mass spectrometry. This technique is based on the ability of a mineral host to facilitate desorption and ionization of bio/organic molecules for detection. Spectra obtained from each aromatic amino acid alone and in combination with thenardite show differences in ionization mechanism and fragmentation patterns. These differences are due to chemical and structural differences between the aromatic side chains of their respective amino acid. Tyrosine and tryptophan when combined with thenardite were observed to undergo cation-attachment ([M+Na]+), due to the high alkali ion affinity of their aromatic side chains. In addition, substitution of the carboxyl group hydrogen by sodium led to formation of [M-H+Na]Na+ peaks. In contrast, phenylalanine mixed with thenardite showed no evidence of Na+ attachment. Understanding how co-deposition of amino acids with thenardite can affect the observed mass spectra is important for future exploration missions that are likely to use laser desorption mass spectrometry to search for bio/organic compounds in extraterrestrial environments.

  6. Effect of Thenardite on the Direct Detection of Aromatic Amino Acids: Implications for the Search for Life in the Solar System

    Energy Technology Data Exchange (ETDEWEB)

    C. Doc Richardson; Nancy W. Hinman; Jill R. Scott

    2009-10-01

    With the discovery of Na-sulfate minerals on Mars and Europa, recent studies using these minerals have focused on their ability to assist in the detection of bio/organic signatures. This study further investigates the ability of thenardite (Na2SO4) to effectively facilitate the ionization and identification of aromatic amino acids (phenylalanine, tyrosine, and tryptophan) using a technique called geomatrix-assisted laser desorption/ionization (GALDI) in conjunction with a Fourier transform mass spectrometry (FTICR-MS). This technique is based on the ability of a mineral host to facilitate the ionization and detection of bio/organic molecules. Spectra obtained from each aromatic amino acid alone and in combination with thenardite show differences in ionization mechanism and fragmentation patterns. These differences are due to chemical and structural differences between the aromatic side chains of their respective amino acid. Tyrosine and tryptophan when combined with thenardite were observed to undergo cation-attachment ([M+Na]+), due to the high alkali affinity of their aromatic side chains. Subsequent cation substitution of the carboxyl group led to formation double cation-attached peaks ([M-H+Na]Na+). In contrast, phenylalanine mixed with thenardite showed no evidence of Na+ interaction. Understanding how codeposition of amino acids with thenardite can affect the observed mass spectra is important for future exploration missions that are likely to use laser desorption mass spectrometry to search for bio/organic compounds in extraterrestrial environments.

  7. Excretion of amino acids by humans during space flight

    Science.gov (United States)

    Stein, T. P.; Schluter, M. D.

    1998-01-01

    We measured the urine amino acid distribution patterns before, during and after space flight on the Space Shuttle. The urine samples were collected on two separate flights of the space shuttle. The first flight lasted 9.5 days and the second flight 15 days. Urine was collected continuously on 8 subjects for the period beginning 10 d before launch to 6 d after landing. Results: In contrast to the earlier Skylab missions where a pronounced amino aciduria was found, on shuttle the urinary amino acids showed little change with spaceflight except for a marked decrease in all of the amino acids on FD (flight day) 1 (pvaline on FD3 and FD4 (p<0.05). Conclusions: (i) Amino aciduria is not an inevitable consequence of space flight. (ii) The occurrence of amino aciduria, like muscle protein breakdown is a mission specific effect rather than part of the general human response to microgravity.

  8. Stable isotope studies reveal pathways for the incorporation of non-essential amino acids in Acyrthosiphon pisum (pea aphids).

    Science.gov (United States)

    Haribal, Meena; Jander, Georg

    2015-12-01

    Plant roots incorporate inorganic nitrogen into the amino acids glutamine, glutamic acid, asparagine and aspartic acid, which together serve as the primary metabolites of nitrogen transport to other tissues. Given the preponderance of these four amino acids, phloem sap is a nutritionally unbalanced diet for phloem-feeding insects. Therefore, aphids and other phloem feeders typically rely on microbial symbionts for the synthesis of essential amino acids. To investigate the metabolism of the four main transport amino acids by the pea aphid (Acyrthosiphon pisum), and its Buchnera aphidicola endosymbionts, aphids were fed defined diets with stable isotope-labeled glutamine, glutamic acid, asparagine or aspartic acid (U-(13)C, U-(15)N; U-(15)N; α-(15)N; or γ-(15)N). The metabolic fate of the dietary (15)N and (13)C was traced using gas chromatography-mass spectrometry (GC-MS). Nitrogen was the major contributor to the observed amino acid isotopomers with one additional unit mass (M+1). However, there was differential incorporation, with the amine nitrogen of asparagine being incorporated into other amino acids more efficiently than the amide nitrogen. Higher isotopomers (M+2, M+3 and M+4) indicated the incorporation of varying numbers of (13)C atoms into essential amino acids. GC-MS assays also showed that, even with an excess of dietary labeled glutamine, glutamic acid, asparagine or aspartic acid, the overall content of these amino acids in aphid bodies was mostly the product of catabolism of dietary amino acids and subsequent re-synthesis within the aphids. Thus, these predominant dietary amino acids are not passed directly to Buchnera endosymbionts for synthesis of essential amino acids, but are rather are produced de novo, most likely by endogenous aphid enzymes. PMID:26632455

  9. 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

  10. Non-protein amino acids in peptide design

    Indian Academy of Sciences (India)

    S Aravinda; N Shamala; Rituparna S Roy; P Balaram

    2003-10-01

    An overview of the use of non-protein amino acids in the design of conformationally well-defined peptides, based on work from the author’s laboratory, is discussed. The crystal structures of several designed oligopeptides illustrate the use -aminoisobutyric acid (Aib) in the construction of helices, D-amino acids in the design of helix termination segments and DPro-Xxx segments for nucleating of -hairpin structures. - and -amino acid residues have been used to expand the range of designed polypeptide structures.

  11. Use of fuzzy clustering technique and matrices to classify amino acids and its impact to Chou's pseudo amino acid composition

    OpenAIRE

    Georgiou, D. N.; Karakasidis, T.E.; Nieto, J J; Torres, A.

    2009-01-01

    Use of fuzzy clustering technique and matrices to classify amino acids and its impact to Chou's pseudo amino acid composition correspondence: Corresponding author. Tel.: +302421074163. (Karakasidis, T.E.) (Karakasidis, T.E.) University of Patras, Department of Mathematics - 265 00 Patras--> - GREECE (Georgiou, D.N.) University of Thessaly, Department of Civil Engineering - 383 34 Volos--> - GREECE (Karakas...

  12. Quantitative analysis of 17 amino acids in tobacco leaves using an amino acid analyzer and chemometric resolution.

    Science.gov (United States)

    Zeng, Yihang; Cai, Wensheng; Shao, Xueguang

    2015-06-01

    A method was developed for quantifying 17 amino acids in tobacco leaves by using an A300 amino acid analyzer and chemometric resolution. In the method, amino acids were eluted by the buffer solution on an ion-exchange column. After reacting with ninhydrin, the derivatives of amino acids were detected by ultraviolet detection. Most amino acids are separated by the elution program. However, five peaks of the derivatives are still overlapping. A non-negative immune algorithm was employed to extract the profiles of the derivatives from the overlapping signals, and then peak areas were adopted for quantitative analysis of the amino acids. The method was validated by the determination of amino acids in tobacco leaves. The relative standard deviations (n = 5) are all less than 2.54% and the recoveries of the spiked samples are in a range of 94.62-108.21%. The feasibility of the method was proved by analyzing the 17 amino acids in 30 tobacco leaf samples.

  13. 4,4-Dimethyl- and diastereomeric 4-hydroxy-4-methyl-(2S)-glutamate analogues display distinct pharmacological profiles at ionotropic glutamate receptors and excitatory amino acid transporters

    DEFF Research Database (Denmark)

    Bunch, Lennart; Pickering, Darryl S; Gefflaut, Thierry;

    2009-01-01

    Subtype-selective ligands are of great interest to the scientific community, as they provide a tool for investigating the function of one receptor or transporter subtype when functioning in its native environment. Several 4-substituted (S)-glutamate (Glu) analogues were synthesized, and altogethe...

  14. Organometallic and Bioorganometallic Chemistry – Ferrocene Amino Acids

    Directory of Open Access Journals (Sweden)

    Barišić, L.

    2012-01-01

    Full Text Available This article is the second part of a series dealing with organometallic and bioorganometallic chemistry. In the first part of this series a short review on the history and development of these disciplines was given, emphasizing the importance and scope of bioorganometallic chemistry as a new field dealing with conjugates of organometallics and biomolecules (DNA, PNA, amino acids, peptides.... From the variety of biorganometallics, syntheses and properties of simple conjugates of ferrocene with natural amino acids/peptides were elaborated inter alia. This material is the basis for the second part in which ferrocene amino acids are described. The introduction presents nonproteinogenic alicyclic and aromatic amino acids as the models for the title compounds. Naturally occurring amino acids labelled with ferrocene moiety mostly retain properties of the biomolecules included. Contrary to these ω-ferrocenylamino acids, one could imagine specific amino acids with inserted ferrocene core belonging to either homo- or heterodisubstituted type. The central part of this article is devoted to our investigations of the second type - H2N-(CH2m-Fn-(CH2n-COOH. The general rational procedure for synthesis of these compounds and of their N- and/or C-protected derivatives via the azide intermediates N3-CO-(CH2m- Fn-(CH2n-COOMe has been described. In the solid state derivatives of ferrocene amino acids contain intermolecular hydrogen bonds giving dimeric structures, three-dimensional networks or endless helical chains. The solutions of homologues Ac-NH-(CH2m-Fn-(CH2n-COOMe in nonpolar solvents are dominated by open form conformers. Compounds containing 2–3 ferrocene cores connected by amide, imide and oxalamide spacers were prepared by oligomerization of 1'-aminoferrocene-1-carboxylic acid (Fca or by its condensation with the appropriate reagents. Similar to natural amino acids, ferrocene amino acids are water-soluble substances with high melting points

  15. Amino acid composition of parturient plasma, the intervillous space of the placenta and the umbilical vein of term newborn infants

    Directory of Open Access Journals (Sweden)

    J.S. Camelo Jr.

    2004-05-01

    Full Text Available The objective of the present study was to determine the levels of amino acids in maternal plasma, placental intervillous space and fetal umbilical vein in order to identify the similarities and differences in amino acid levels in these compartments of 15 term newborns from normal pregnancies and deliveries. All amino acids, except tryptophan, were present in at least 186% higher concentrations in the intervillous space than in maternal venous blood, with the difference being statistically significant. This result contradicted the initial hypothesis of the study that the plasma amino acid levels in the placental intervillous space should be similar to those of maternal plasma. When the maternal venous compartment was compared with the umbilical vein, we observed values 103% higher on the fetal side which is compatible with currently accepted mechanisms of active amino acid transport. Amino acid levels of the placental intervillous space were similar to the values of the umbilical vein except for proline, glycine and aspartic acid, whose levels were significantly higher than fetal umbilical vein levels (average 107% higher. The elevated levels of the intervillous space are compatible with syncytiotrophoblast activity, which maintain high concentrations of free amino acids inside syncytiotrophoblast cells, permitting asymmetric efflux or active transport from the trophoblast cells to the blood in the intervillous space. The plasma amino acid levels in the umbilical vein of term newborns probably may be used as a standard of local normality for clinical studies of amino acid profiles.

  16. Amino acid profiles and digestible indispensable amino acid scores of proteins from the prioritized key foods in Bangladesh.

    Science.gov (United States)

    Shaheen, Nazma; Islam, Saiful; Munmun, Sarah; Mohiduzzaman, Md; Longvah, Thingnganing

    2016-12-15

    Concentrations of standard amino acids were determined in the composite samples (representing 30 agro-ecological zones of Bangladesh) of six prioritized key dietary protein sources: Oryza sativa (rice), Triticum aestivum (wheat flour), Lens culinaris (lentils), Pangusius pangusius (pangas), Labeo rohita (rohu) and Oreochromis mossambicus (tilapia). Digestible indispensable amino acid scores (DIAAS) was calculated using published data on amino acids' digestibility to evaluate the protein quality of these foods. Indispensable amino acid (IAA) contents (mg IAA/g protein), found to be highest in pangas (430) and lowest in wheat (336), of all these analyzed foods exceeded the FAO recommended daily allowance (277mg IAA/g protein) and contributed on average 40% to total amino acid contents. Untruncated DIAAS values ranged from 51% (lysine) in wheat to 106% (histidine) in pangas and distinguished pangas, rohu, and tilapia containing 'excellent quality' protein (DIAAS>100%) with potential to complement lower quality protein of cereals, fruits, and vegetables. PMID:27451158

  17. Amino Acid and Peptide Immobilization on Oxidized Nanocellulose: Spectroscopic Characterization

    Directory of Open Access Journals (Sweden)

    Claude Daneault

    2012-06-01

    Full Text Available In this work, oxidized nanocellulose (ONC was synthesized and chemically coupled with amino acids and peptides using a two step coupling method at room temperature. First, ONC was activated by N-ethyl-N’-(3-dimethylaminopropyl carbodiimide hydrochloride, forming a stable active ester in the presence of N-hydroxysuccinimide. Second, the active ester was reacted with the amino group of the amino acid or peptide, forming an amide bond between ONC and the grafted molecule. Using this method, the intermolecular interaction of amino acids and peptides was avoided and uniform coupling of these molecules on ONC was achieved. The coupling reaction was very fast in mild conditions and without alteration of the polysaccharide. The coupling products (ONC-amino acids and ONC-peptides were characterized by transmission electron microscopy and by the absorption, emission, Fourier transform infrared spectroscopy (FTIR and X-ray photoelectron spectroscopy (XPS spectroscopic techniques.

  18. Solubility of xenon in amino-acid solutions. II. Nine less-soluble amino acids

    Science.gov (United States)

    Kennan, Richard P.; Himm, Jeffrey F.; Pollack, Gerald L.

    1988-05-01

    Ostwald solubility (L) of xenon gas, as the radioisotope 133Xe, has been measured as a function of solute concentration, at 25.0 °C, in aqueous solutions of nine amino acids. The amino-acid concentrations investigated covered much of their solubility ranges in water, viz., asparagine monohydrate (0-0.19 M), cysteine (0-1.16 M), glutamine (0-0.22 M), histidine (0-0.26 M), isoleucine (0-0.19 M), methionine (0-0.22 M), serine (0-0.38 M), threonine (0-1.4 M), and valine (0-0.34 M). We have previously reported solubility results for aqueous solutions of six other, generally more soluble, amino acids (alanine, arginine, glycine, hydroxyproline, lysine, and proline), of sucrose and sodium chloride. In general, L decreases approximately linearly with increasing solute concentration in these solutions. If we postulate that the observed decreases in gas solubility are due to hydration, the results under some assumptions can be used to calculate hydration numbers (H), i.e., the number of H2O molecules associated with each amino-acid solute molecule. The average values of hydration number (H¯) obtained at 25.0 °C are 15.3±1.5 for asparagine, 6.8±0.3 for cysteine, 11.5±1.1 for glutamine, 7.3±0.7 for histidine, 5.9±0.4 for isoleucine, 10.6±0.8 for methionine, 11.2±1.3 for serine, 7.7± 1.0 for threonine, and 6.6±0.6 for valine. We have also measured the temperature dependence of solubility L(T) from 5-40 °C for arginine, glycine, and proline, and obtained hydration numbers H¯(T) in this range. Between 25-40 °C, arginine has an H¯ near zero. This may be evidence for an attractive interaction between xenon and arginine molecules in aqueous solution.

  19. Conformational Interconversions of Amino Acid Derivatives.

    Science.gov (United States)

    Kaminský, Jakub; Jensen, Frank

    2016-02-01

    Exhaustive conformational interconversions including transition structure analyses of N-acetyl-l-glycine-N-methylamide as well as its alanine, serine, and cysteine analogues have been investigated at the MP2/6-31G** level, yielding a total of 142 transition states. Improved estimates of relative energies were obtained by separately extrapolating the Hartree-Fock and MP2 energies to the basis set limit and adding the difference between CCSD(T) and MP2 results with the cc-pVDZ basis set to the extrapolated MP2 results. The performance of eight empirical force fields (AMBER94, AMBER14SB, MM2, MM3, MMFFs, CHARMM22_CMAP, OPLS_2005, and AMOEBAPRO13) in reproducing ab initio energies of transition states was tested. Our results indicate that commonly used class I force fields employing a fixed partial charge model for the electrostatic interaction provide mean errors in the ∼10 kJ/mol range for energies of conformational transition states for amino acid conformers. Modern reparametrized versions, such as CHARMM22_CMAP, and polarizable force fields, such as AMOEBAPRO13, have slightly lower mean errors, but maximal errors are still in the 35 kJ/mol range. There are differences between the force fields in their ability for reproducing conformational transitions classified according to backbone/side-chain or regions in the Ramachandran angles, but the data set is likely too small to draw any general conclusions. Errors in conformational interconversion barriers by ∼10 kJ/mol suggest that the commonly used force field may bias certain types of transitions by several orders of magnitude in rate and thus lead to incorrect dynamics in simulations. It is therefore suggested that information for conformational transition states should be included in parametrizations of new force fields. PMID:26691979

  20. Expanding the amino acid repertoire of ribosomal polypeptide synthesis via the artificial division of codon boxes

    Science.gov (United States)

    Iwane, Yoshihiko; Hitomi, Azusa; Murakami, Hiroshi; Katoh, Takayuki; Goto, Yuki; Suga, Hiroaki

    2016-04-01

    In ribosomal polypeptide synthesis the library of amino acid building blocks is limited by the manner in which codons are used. Of the proteinogenic amino acids, 18 are coded for by multiple codons and therefore many of the 61 sense codons can be considered redundant. Here we report a method to reduce the redundancy of codons by artificially dividing codon boxes to create vacant codons that can then be reassigned to non-proteinogenic amino acids and thereby expand the library of genetically encoded amino acids. To achieve this, we reconstituted a cell-free translation system with 32 in vitro transcripts of transfer RNASNN (tRNASNN) (S = G or C), assigning the initiator and 20 elongator amino acids. Reassignment of three redundant codons was achieved by replacing redundant tRNASNNs with tRNASNNs pre-charged with non-proteinogenic amino acids. As a demonstration, we expressed a 32-mer linear peptide that consists of 20 proteinogenic and three non-proteinogenic amino acids, and a 14-mer macrocyclic peptide that contains more than four non-proteinogenic amino acids.

  1. Cortical and subcortical gamma amino acid butyric acid deficits in anxiety and stress disorders: Clinical implications

    OpenAIRE

    Goddard, Andrew W

    2016-01-01

    Anxiety and stress disorders are a major public health issue. However, their pathophysiology is still unclear. The gamma amino acid butyric acid (GABA) neurochemical system has been strongly implicated in their pathogenesis and treatment by numerous preclinical and clinical studies, the most recent of which have been highlighted and critical review in this paper. Changes in cortical GABA appear related to normal personality styles and responses to stress. While there is accumulating animal an...

  2. Site specific incorporation of heavy atom-containing unnatural amino acids into proteins for structure determination

    Science.gov (United States)

    Xie, Jianming; Wang, Lei; Wu, Ning; Schultz, Peter G.

    2008-07-15

    Translation systems and other compositions including orthogonal aminoacyl tRNA-synthetases that preferentially charge an orthogonal tRNA with an iodinated or brominated amino acid are provided. Nucleic acids encoding such synthetases are also described, as are methods and kits for producing proteins including heavy atom-containing amino acids, e.g., brominated or iodinated amino acids. Methods of determining the structure of a protein, e.g., a protein into which a heavy atom has been site-specifically incorporated through use of an orthogonal tRNA/aminoacyl tRNA-synthetase pair, are also described.

  3. Classification and identification of amino acids based on THz spectroscopy

    Science.gov (United States)

    Huang, Ping J.; Ma, Ye H.; Li, Xian; Hou, Di B.; Cai, Jin H.; Zhang, Guang X.

    2015-11-01

    Amino acids are important nutrient substances for life, and many of them have several isomerides, while only L-type amino acids can be absorbed by body as nutrients. So it is certain worth to accurately classify and identify amino acids. In this paper, terahertz time-domain spectroscopy (THz-TDS) was used to detect isomers of various amino acids to obtain their absorption spectra, and their spectral characteristics were analyzed and compared. Results show that not all isomerides of amino acids have unique spectral characteristics, causing the difficulty of classification and identification. To solve this problem, partial least squares discriminant analysis (PLS-DA), firstly, was performed on extracting principal component of THz spectroscopy and classifying amino acids. Moreover, variable selection (VS) was employed to optimize spectral interval of feature extraction to improve analysis effect. As a result, the optimal classification model was determined and most samples can be accurately classified. Secondly, for each class of amino acids, PLS-DA combined with VS was also applied to identify isomerides. This work provides a suggestion for material classification and identification with THz spectroscopy.

  4. 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.

  5. Microbial Products Trigger Amino Acid Exudation from Plant Roots1

    Science.gov (United States)

    Phillips, Donald A.; Fox, Tama C.; King, Maria D.; Bhuvaneswari, T.V.; Teuber, Larry R.

    2004-01-01

    Plants naturally cycle amino acids across root cell plasma membranes, and any net efflux is termed exudation. The dominant ecological view is that microorganisms and roots passively compete for amino acids in the soil solution, yet the innate capacity of roots to recover amino acids present in ecologically relevant concentrations is unknown. We find that, in the absence of culturable microorganisms, the influx rates of 16 amino acids (each supplied at 2.5 μm) exceed efflux rates by 5% to 545% in roots of alfalfa (Medicago sativa), Medicago truncatula, maize (Zea mays), and wheat (Triticum aestivum). Several microbial products, which are produced by common soil microorganisms such as Pseudomonas bacteria and Fusarium fungi, significantly enhanced the net efflux (i.e. exudation) of amino acids from roots of these four plant species. In alfalfa, treating roots with 200 μm phenazine, 2,4-diacetylphloroglucinol, or zearalenone increased total net efflux of 16 amino acids 200% to 2,600% in 3 h. Data from 15N tests suggest that 2,4-diacetylphloroglucinol blocks amino acid uptake, whereas zearalenone enhances efflux. Thus, amino acid exudation under normal conditions is a phenomenon that probably reflects both active manipulation and passive uptake by microorganisms, as well as diffusion and adsorption to soil, all of which help overcome the innate capacity of plant roots to reabsorb amino acids. The importance of identifying potential enhancers of root exudation lies in understanding that such compounds may represent regulatory linkages between the larger soil food web and the internal carbon metabolism of the plant. PMID:15347793

  6. Connecting Source with Sink: The Role of Arabidopsis AAP8 in Phloem Loading of Amino Acids.

    Science.gov (United States)

    Santiago, James P; Tegeder, Mechthild

    2016-05-01

    Allocation of large amounts of nitrogen to developing organs occurs in the phloem and is essential for plant growth and seed development. In Arabidopsis (Arabidopsis thaliana) and many other plant species, amino acids represent the dominant nitrogen transport forms in the phloem, and they are mainly synthesized in photosynthetically active source leaves. Following their synthesis, a broad spectrum of the amino nitrogen is actively loaded into the phloem of leaf minor veins and transported within the phloem sap to sinks such as developing leaves, fruits, or seeds. Controlled regulation of the source-to-sink transport of amino acids has long been postulated; however, the molecular mechanism of amino acid phloem loading was still unknown. In this study, Arabidopsis AMINO ACID PERMEASE8 (AAP8) was shown to be expressed in the source leaf phloem and localized to the plasma membrane, suggesting its function in phloem loading. This was further supported by transport studies with aap8 mutants fed with radiolabeled amino acids and by leaf exudate analyses. In addition, biochemical and molecular analyses revealed alterations in leaf nitrogen pools and metabolism dependent on the developmental stage of the mutants. Decreased amino acid phloem loading and partitioning to sinks led to decreased silique and seed numbers, but seed protein levels were unchanged, demonstrating the importance of AAP8 function for sink development rather than seed quality. Overall, these results show that AAP8 plays an important role in source-to-sink partitioning of nitrogen and that its function affects source leaf physiology and seed yield. PMID:27016446

  7. Plasmon resonance enhancement of nonlinear properties of amino acids

    Science.gov (United States)

    de Araujo, Renato E.; Rativa, Diego; Gomes, Anderson S. L.

    2007-02-01

    Here we analyze the influence of 9 nm (mean diameter) silver particles on the nonlinear properties of intrinsic cell molecules. A novel high sensitivity thermal managed eclipse Z-scan technique with a femtosecond laser system was used to analyze the nonlinear susceptibility of water solution of fluorescent and non-fluorescent amino acids (Tryptophan, Tyrosine, Phenylalanine, Proline and Histidine) with different concentration of silver nanoparticles. The generalized Maxwell Garnett model is used to explain the behavior of the measured nonlinear refractive index with the change of the nanoparticles concentration in the sample.

  8. Exhaustive Database Searching for Amino Acid Mutations in Proteomes

    Energy Technology Data Exchange (ETDEWEB)

    Hyatt, Philip Douglas [ORNL; Pan, Chongle [ORNL

    2012-01-01

    Amino acid mutations in proteins can be found by searching tandem mass spectra acquired in shotgun proteomics experiments against protein sequences predicted from genomes. Traditionally, unconstrained searches for amino acid mutations have been accomplished by using a sequence tagging approach that combines de novo sequencing with database searching. However, this approach is limited by the performance of de novo sequencing. The Sipros algorithm v2.0 was developed to perform unconstrained database searching using high-resolution tandem mass spectra by exhaustively enumerating all single non-isobaric mutations for every residue in a protein database. The performance of Sipros for amino acid mutation identification exceeded that of an established sequence tagging algorithm, Inspect, based on benchmarking results from a Rhodopseudomonas palustris proteomics dataset. To demonstrate the viability of the algorithm for meta-proteomics, Sipros was used to identify amino acid mutations in a natural microbial community in acid mine drainage.

  9. The origin of amino acids in lunar regolith samples

    Science.gov (United States)

    Elsila, Jamie E.; Callahan, Michael P.; Dworkin, Jason P.; Glavin, Daniel P.; McLain, Hannah L.; Noble, Sarah K.; Gibson, Everett K.

    2016-01-01

    We analyzed the amino acid content of seven lunar regolith samples returned by the Apollo 16 and Apollo 17 missions and stored under NASA curation since collection using ultrahigh-performance liquid chromatography with fluorescence detection and time-of-flight mass spectrometry. Consistent with results from initial analyses shortly after collection in the 1970s, we observed amino acids at low concentrations in all of the curated samples, ranging from 0.2 parts-per-billion (ppb) to 42.7 ppb in hot-water extracts and 14.5-651.1 ppb in 6 M HCl acid-vapor-hydrolyzed, hot-water extracts. Amino acids identified in the Apollo soil extracts include glycine, D- and L-alanine, D- and L-aspartic acid, D- and L-glutamic acid, D- and L-serine, L-threonine, and L-valine, all of which had previously been detected in lunar samples, as well as several compounds not previously identified in lunar regoliths: α-aminoisobutyric acid (AIB), D- and L-β-amino-n-butyric acid (β-ABA), DL-α-amino-n-butyric acid, γ-amino-n-butyric acid, β-alanine, and ε-amino-n-caproic acid. We observed an excess of the L enantiomer in most of the detected proteinogenic amino acids, but racemic alanine and racemic β-ABA were present in some samples. We also examined seven samples from Apollo 15, 16, and 17 that had been previously allocated to a non-curation laboratory, as well as two samples of terrestrial dunite from studies of lunar module engine exhaust that had been stored in the same laboratory. The amino acid content of these samples suggested that contamination had occurred during non-curatorial storage. We measured the compound-specific carbon isotopic ratios of glycine, β-alanine, and L-alanine in Apollo regolith sample 70011 and found values of -21‰ to -33‰. These values are consistent with those seen in terrestrial biology and, together with the enantiomeric compositions of the proteinogenic amino acids, suggest that terrestrial biological contamination is a primary source of the

  10. EFFECT OF TETRACYCLINES ON THE INTRACELLULAR AMINO ACIDS OF MOLDS.

    Science.gov (United States)

    FREEMAN, B A; CIRCO, R

    1963-07-01

    Freeman, Bob A. (University of Chicago, Chicago, Ill.) and Richard Circo. Effect of tetracyclines on the intracellular amino acids of molds. J. Bacteriol. 86:38-44. 1963.-The tetracycline antibiotics were shown to alter the amino acid metabolism of molds whose growth is not markedly affected. Eight molds were grown in the presence of these antiobiotics; four exhibited a general reduction in the concentration of the intracellular amino acids, except for glutamic acid and alanine. In most of these four cultures, the tetracyclines also caused the complete disappearance of arginine, lysine, proline, phenylalanine, and tyrosine from the intracellular amino acid pool. The significance of these observations and the usefulness of the method in the study of the mechanisms of antibiotic action are discussed. PMID:14051820

  11. Digestible indispensable amino acid score and digestible amino acids in eight cereal grains.

    Science.gov (United States)

    Cervantes-Pahm, Sarah K; Liu, Yanhong; Stein, Hans H

    2014-05-01

    To determine values for the digestible indispensable amino acid score (DIAAS), it is recommended that ileal amino acid (AA) digestibility values obtained in growing pigs are used to characterise protein quality in different foods. Therefore, an experiment was conducted to determine the standardised ileal digestibility (SID) of AA in eight cereal grains (yellow dent maize, Nutridense maize, dehulled barley, dehulled oats, polished white rice, rye, sorghum and wheat) fed to pigs, where SID values in pigs can be used to calculate approximate DIAAS values in humans. In the present experiment, twenty-four barrows with a T-cannula inserted in the distal ileum were allotted to eight diets and fed for three periods to give a total of nine replicate pigs per diet. Each period lasted 14 d, and ileal digesta samples were collected on days 13 and 14. Among the SID values obtained for all cereal grains, values for total indispensable AA were greatest (Poats, but greater (Pcereal grains, and the concentrations of SID indispensable AA in Nutridense maize were greater (Pcereal grains, except rye. In conclusion, results indicate that to meet dietary requirements for AA in humans, diets based on yellow dent maize or sorghum require more AA supplementation than diets based on other cereal grains.

  12. Metabolic Response of Pakchoi Leaves to Amino Acid Nitrogen

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-li; YU Wen-juan; ZHOU Qian; HAN Rui-feng; HUANG Dan-feng

    2014-01-01

    Different nitrogen (N) forms may cause changes in the metabolic profiles of plants. However, few studies have been conducted on the effects of amino acid-N on plant metabolic proifles. The main objective of this study was to identify primary metabolites associated with amino acid-N (Gly, Gln and Ala) through metabolic proifle analysis using gas chromatography-mass spectrometry (GC-MS). Plants of pakchoi (Brassica campestris L. ssp. chinensis L.), Huawang and Wuyueman cultivars, were grown with different nitrogen forms (i.e., Gly, Gln, Ala, NO3--N, and N starvation) applied under sterile hydroponic conditions. The fresh weight and plant N accumulation of Huawang were greater than those of Wuyueman, which indicates that the former exhibited better N-use efficiency than the latter. The physiological performances of the applied N forms were generally in the order of NO3--N>Gln>Gly>Ala. The metabolic analysis of leaf polar extracts revealed 30 amino acid N-responsive metabolites in the two pakchoi cultivars, mainly consisting of sugars, amino acids, and organic acids. Changes in the carbon metabolism of pakchoi leaves under amino acid treatments occurred via the accumulation of fructose, glucose, xylose, and arabinose. Disruption of amino acid metabolism resulted in accumulation of endogenous Gly in Gly treatment, Pro in Ala treatment, and Asn in three amino acid (Gly, Gln and Ala) treatments. By contrast, the levels of endogenous Gln and Leu decreased. However, this reduction varied among cultivars and amino acid types. Amino acid-N supply also affected the citric acid cycle, namely, the second stage of respiration, where leaves in Gly, Gln and Ala treatments contained low levels of malic, citric and succinic acids compared with leaves in NO3--N treatments. No signiifcant difference in the metabolic responses was observed between the two cultivars which differed in their capability to use N. The response of primary metabolites in pakchoi leaves to amino acid-N supply

  13. Hybride magnetic nanostructure based on amino acids functionalized polypyrrole

    Energy Technology Data Exchange (ETDEWEB)

    Nan, Alexandrina, E-mail: alexandrina.nan@itim-cj.ro; Bunge, Alexander; Turcu, Rodica [National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donat, 400293 Cluj-Napoca (Romania)

    2015-12-23

    Conducting polypyrrole is especially promising for many commercial applications because of its unique optical, electric, thermal and mechanical properties. We report the synthesis and characterization of novel pyrrole functionalized monomers and core-shell hybrid nanostructures, consisting of a conjugated polymer layer (amino acids functionalized pyrrole copolymers) and a magnetic nanoparticle core. For functionalization of the pyrrole monomer we used several amino acids: tryptophan, leucine, phenylalanine, serine and tyrosine. These amino acids were linked via different types of hydrophobic linkers to the nitrogen atom of the pyrrole monomer. The magnetic core-shell hybrid nanostructures are characterized by various methods such as FTIR spectroscopy, transmission electron microscopy (TEM) and magnetic measurements.

  14. Hybride magnetic nanostructure based on amino acids functionalized polypyrrole

    Science.gov (United States)

    Nan, Alexandrina; Bunge, Alexander; Turcu, Rodica

    2015-12-01

    Conducting polypyrrole is especially promising for many commercial applications because of its unique optical, electric, thermal and mechanical properties. We report the synthesis and characterization of novel pyrrole functionalized monomers and core-shell hybrid nanostructures, consisting of a conjugated polymer layer (amino acids functionalized pyrrole copolymers) and a magnetic nanoparticle core. For functionalization of the pyrrole monomer we used several amino acids: tryptophan, leucine, phenylalanine, serine and tyrosine. These amino acids were linked via different types of hydrophobic linkers to the nitrogen atom of the pyrrole monomer. The magnetic core-shell hybrid nanostructures are characterized by various methods such as FTIR spectroscopy, transmission electron microscopy (TEM) and magnetic measurements.

  15. Hybride magnetic nanostructure based on amino acids functionalized polypyrrole

    International Nuclear Information System (INIS)

    Conducting polypyrrole is especially promising for many commercial applications because of its unique optical, electric, thermal and mechanical properties. We report the synthesis and characterization of novel pyrrole functionalized monomers and core-shell hybrid nanostructures, consisting of a conjugated polymer layer (amino acids functionalized pyrrole copolymers) and a magnetic nanoparticle core. For functionalization of the pyrrole monomer we used several amino acids: tryptophan, leucine, phenylalanine, serine and tyrosine. These amino acids were linked via different types of hydrophobic linkers to the nitrogen atom of the pyrrole monomer. The magnetic core-shell hybrid nanostructures are characterized by various methods such as FTIR spectroscopy, transmission electron microscopy (TEM) and magnetic measurements

  16. Chemo-enzymatic synthesis of (2S,4R)-2-amino-4-(3-(2,2-diphenylethylamino)-3-oxopropyl)pentanedioic acid

    DEFF Research Database (Denmark)

    Sagot, Emanuelle; Jensen, Anders A.; Pickering, Darryl S;

    2008-01-01

    In the mammalian central nervous system (CNS), the action of sodium dependent excitatory amino acid transporters (EAATs) is responsible for termination of glutamatergic neurotransmission by reuptake of ( S) -glutamate (Glu) from the synaptic cleft. Five EAAT subtypes have been identified, of which...

  17. How amino acids and peptides shaped the RNA world.

    Science.gov (United States)

    van der Gulik, Peter T S; Speijer, Dave

    2015-01-01

    The "RNA world" hypothesis is seen as one of the main contenders for a viable theory on the origin of life. Relatively small RNAs have catalytic power, RNA is everywhere in present-day life, the ribosome is seen as a ribozyme, and rRNA and tRNA are crucial for modern protein synthesis. However, this view is incomplete at best. The modern protein-RNA ribosome most probably is not a distorted form of a "pure RNA ribosome" evolution started out with. Though the oldest center of the ribosome seems "RNA only", we cannot conclude from this that it ever functioned in an environment without amino acids and/or peptides. Very small RNAs (versatile and stable due to basepairing) and amino acids, as well as dipeptides, coevolved. Remember, it is the amino group of aminoacylated tRNA that attacks peptidyl-tRNA, destroying the bond between peptide and tRNA. This activity of the amino acid part of aminoacyl-tRNA illustrates the centrality of amino acids in life. With the rise of the "RNA world" view of early life, the pendulum seems to have swung too much towards the ribozymatic part of early biochemistry. The necessary presence and activity of amino acids and peptides is in need of highlighting. In this article, we try to bring the role of the peptide component of early life back into focus. We argue that an RNA world completely independent of amino acids never existed. PMID:25607813

  18. Searching for Extraterrestrial Amino Acids in a Contaminated Meteorite: Amino Acid Analyses of the Canakkale L6 Chondrite

    Science.gov (United States)

    Burton, A. S.; Elsila, J. E.; Glavin, D. P.; Dworkin, J. P.; Ornek, C. Y.; Esenoglu, H. H.; Unsalan, O.; Ozturk, B.

    2016-01-01

    Amino acids can serve as important markers of cosmochemistry, as their abundances and isomeric and isot