n-alkenyl heme adduct: Topics by WorldWideScience.org

Modulation of the axial water hydrogen-bonding properties by chemical modification of the substrate in resting state, substrate-bound heme oxygenase from Neisseria meningitidis; Coupling to the distal H-bond network via ordered water molecules

Ethyl azidoformate reacts, on thermolysis with acenaphthylene, to give a 1:2 adduct involving sequential aziridine formation, ring-opening to a 1,3-dipolar pyridinium-2,6-betaine, and trapping of the dipole with acenaphthylene. The structure of the adduct was confirmed by X-ray crystallography.

Evidence for Redox Cooperativity between c-Type Hemes of MauG which is Likely Coupled to Oxygen Activation during Tryptophan Tryptophylquinone Biosynthesis

The hydrogen bonding of ligated water in ferric, high-spin, resting-state substrate complexes of heme oxygenase from Neisseria meningitidis has been systematically perturbed...Full Text Available

2006-05-17

Interaction of cis-diamminediaquoplatinum(II) with adenosylcobalamin and alkylcobalamins

MauG is a novel 42 kDa di-heme protein which is required for the biosynthesis of tryptophan tryptophylquinone, the prosthetic group of methylamine dehydrogenase. The visible absorption and resonance...Full Text Available

2006-01-24

The determination of hemoglobin and myoglogin residues as a parameter for testing heat exposure in back bacon.

The interaction of cis-diamminediaquoplatinum(II) nitrate with adenosylcobalamin and a series of alkylcobalamins was studied by carbon-13 nuclear magnetic resonance spectroscopy and by electronic spectroscopy. With these cobalamins cis-(Pt(NH/sub 3/)/sub 2/(OH/sub 2/)/sub 2/)/sup 2 +/ forms adducts in which N(3) of the 5,6-methylbenzimidazole moiety is co-ordinated to platinum(II) rather than to cobalt(III) of the corrin. The chemical shifts of the 5'-methylene carbon of adenosylcobalamin-platinum adduct and of the Co-methyl carbon of the methylcobalamin-platinum adduct are characteristic of these cobalamins in the base-off form. Furthermore, these cobalamin-platinum complexes have visible spectra identical to those of the cobalamins in acidic solution. The /sup 13/C NMR spectrum of the adenosylcobalamin-platinum complex suggests the presence of a second adduct in which platinum(II) complexes ...

1980-01-01

Mechanism of hepatoprotection in proestrus female rats following trauma-hemorrhage: heme oxygenase-1-derived normalization of hepatic inflammatory responses

The use of an extraction of the heme pigments hemoglobin and myoglobin as a test for the heat exposure of back bacon was investigated by treating back bacon at varying temperatures of 50-70 degrees...Full Text Available

1976-07-01

Effectiveness of zinc protoporphyrin/heme ratio for screening iron deficiency in preschool-aged children

Hepatic damage occurs in males and ovariectomized (OVX), not in proestrus (PE), females following trauma-hemorrhage (T-H). The mechanism responsible for hepatoprotection remains unknown. We hypothesized...Full Text Available

2009-06-01

Spectrophotometric studies on the formation of adducts involved in synergistic extraction of uranium (IV) by mixtures of HTTA and neutral donors

Hemoglobin and zinc protoporphyrin (ZPP) tests are commonly used to screen for iron deficiency, but little research has been done to systematically evaluate the sensitivity and specificity of these...Full Text Available

2011-02-01

Investigation of the electronic structure of base adducts derived from tris(#eta#"5-cyclopentadienyl)-lanthanide(III) and related compound types

Adduct formation between U(TTA)_4 and several neutral donor (S) was investigated by utilizing the changes in the absorption spectra of U(IV) resulting from the addition of neutral donors to a solution of U(TTA)_4. All the donors used in the present work from 1:1 adducts with U(TTA)_4. From the spectral changes, the equilibrium constants #beta#sub(AB) for the adduct formation reaction viz U(TTA)_4 S reversible U(TTA)_4.S were calculated for a few neutral donors. The log #beta#sub(AB) values obtained in benzene medium, are :TOPO (6.23), TBPO (6.13), TPPO (4.72), DBBP(4.04) TBP(3.04), TIOTP(1.27) and MIBK(-0.10) and a value of 3.98 for TOPO in chloroform medium. The adduct formation was found to result in increasing the coordination number of U(IV) from 8 in U(TTA)_4 to 9 in the adducts it forms with the neutral donors. Similar absorption spectral studies with U(DBM)_4 revealed that it ...

1979-01-01

Adducted proteins for identification of endogenous electrophiles.

The purpose of this work is the elucidation of the f"n electronic structure of neutral mono base adducts derived from tris(#eta#"5-cyclopentadienyl)-lanthanide(III) (Cp_2Ln). The available data on related compounds like bis adducts and anionic mono adducts of the same moiety was also analyzed. The first aim was to derive the experimental crystal field splitting pattern from optical, magnetooptical and magnetochemical measurements and to reproduce it using an empirical Hamiltonian operator. The eigenvalues and eigenvectors obtained in this manner were used for a quantitative interpretation of the magnetochemical, EPR- and NMR-spectroscopic properties. For the latter subject it was necessary to develop an own procedure for the NMR analysis of paramagnetic compounds. This method is based on factor analysis and as demonstrated in the second part of this work, is clearly superior to all previous procedures. (orig.).

Uragogin and blepharodin, unprecedented hetero-Diels-Alder adducts from Celastraceae species

Chemically reactive compounds in tissues can be monitored through their products of reaction with biomacromolecules. For the purpose of in vivo dose monitoring, hemoglobin (Hb) has been preferred to...Full Text Available

1993-03-01

British Library Electronic Table of Contents (United Kingdom)

Uragogin and blepharodin were isolated from Crossopetalum uragoga and Maytenus magellanica, respectively. They represent the first examples of a triterpene-neolignan ester and a heptacyclic arylpropanoid-nor-triterpenephenol, hetero-Diels-Alder adducts built with dioxane bridges. Their proposed biosynthetic route is discussed.

2011-01-01

Polycyclic Aromatic Hydrocarbon (PAH) Exposure and DNA Adduct Semi-Quantitation in Archived Human Tissues

DNA adducts in peripheral blood lymphocytes from aluminum production plant workers determined by 32P-postlabeling and enzyme-linked immunosorbent assay.

Polycyclic aromatic hydrocarbons (PAHs) are combustion products of organic materials, mixtures of which contain multiple known and probable human carcinogens. PAHs occur in indoor and outdoor air, as well as in char-broiled meats and fish. Human exposure to PAHs occurs by inhalation, ingestion and topical absorption, and subsequently formed metabolites are either rendered hydrophilic and excreted, or bioactivated and bound to cellular macromolecules. The formation of PAH-DNA adducts (DNA binding products), considered a necessary step in PAH-initiated carcinogenesis, has been widely studied in experimental models and has been documented in human tissues. This review describes immunohistochemistry (IHC) studies, which reveal localization of PAH-DNA adducts in human tissues, and semi-quantify PAH-DNA adduct levels using the Automated Cellular Imaging System (ACIS). These studies have shown that PAH-DNA ...

2011-07-29

Benzo[a]pyrene diol epoxide-DNA cis adduct formation through a trans?chlorohydrin?intermediate

32P-Postlabeling analysis and enzyme-linked immunosorbent assay (ELISA) have been used to detect DNA adducts in peripheral blood lymphocytes from primary aluminum production plant workers who were exposed...Full Text Available

1993-03-01

Crystal structure of ball-milled mixture of sodium chloride and magnesium chloride-ethanol adduct

Alkylation of DNA by 7r,8t-dihydroxy,9t,10t-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (anti-BPDE) forms mainly trans adducts (with respect to the C-9/10...Full Text Available

1997-03-04

Interaction of thyroid hormone and hemoglobin: nature of the interaction and effect of hemoglobin on thyroid hormone radioimmunoassay

NaCl doped MgCl_2.nEtOH adducts were prepared by ball-milling MgCl_2.2.5EtOH with NaCl. Both the ball-milled MgCl_2.nEtOH/NaCl mixture and pure MgCl_2.2.5EtOH adducts were analyzed by X-ray diffraction (XRD), transmission electron microscope (TEM), thermogravimetry (TG) and differencial scanning calorimetry (DSC). A simple MgCl_2.nEtOH/NaCl mixture without ball-milling treatment was also studied for comparison. Two kinds of mixed crystals, Na_2MgCl_4 and NaMgCl_3, were found to be formed in a ball-milled mixture that contained 16 mol.% NaCl. TG and DSC analysis of the samples also provided indirect evidences supporting the presence of the mixed crystals in the ball-milled mixture. Adding certain amounts of NaCl in MgCl_2.2.5EtOH adduct, either by co-milling or by simple mixing, greatly increased the thermal stability of the adduct, but thermal decomposition behaviour of the ball-milled mixture was still ...

2008-02-05

Formation, Repair, and Genotoxic Properties of Bulky DNA Adducts Formed from Tobacco-Specific Nitrosamines

Gel filtration of human erythrocyte (RBC) lysate incubated with labeled thyroxine (Tu) or triiodothyronine (Tt) revealed co-elution of a major iodothyronine-binding fraction (R-2) and hemoglobin. Solutions of purified human hemoglobin and Tt also showed co-elution of hormone and hemoglobin. Because hematin and protoporphyrin were shown to bind labeled Tt, the oxygen-binding site on hemoglobin was excluded as the site of iodothyronine-hemoglobin interaction. Analysis of hormone binding by heme and globin moieties showed Tt binding to be limited to the heme fraction. Addition of excess unlabeled Tt to hemoglobin or heme incubated with labeled Tt indicated 75% to 90% of hormone binding was poorly dissociable. These observations suggested that the presence of hemoglobin in RBC lysate or in serum could influence the measurement of Tu and Tt by specific radioimmunoassay (RIA). Subsequent studies of the addition to serum of human ...

Alkyl acrylate adducts of polyamines, ether amines and ether polyamines

4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N′-nitrosonornicotine (NNN) are tobacco-specific nitrosamines present in tobacco products and smoke. Both compounds...Full Text Available

Synergistic extraction of europium(III) with benzoic acid and thenoyltrifluoroacetone

Disclosed are additives for hydrocarbon fuels which are the reaction products of a polyamine and an alkyl ester of acrylic or alkyl acrylic acid. A preferred composition is a mixture of the reaction product and oxygenated or non-oxygenated mono- or polyamines.

1980-12-23

1 2 3 4

Spectroscopic, Structural, and Functional Characterization of the Alternative Low-Spin State of Horse Heart Cytochrome c

The solvent extraction of europium(III) into solutions of thenoyltrifluoroacetone and benzoic acid in cyclohexane, carbon tetrachloride, benzene, chloroform, pentachloroethane, and tetrachloroethane has been measured at 25/sup 0/ C. It has been found that the extracted species involve two types of adducts, EuA/sub 3/HB and EuA/sub 3/ . 2HB where A denotes the TTA anion and HB the benzoic acid monomer. The magnitude of the adduct formation constants in different solvents has been correlated with the dimerization constants of benzoic acid in the solvents. 2 figures, 2 tables.

1983-01-01

Some relationships between ultraviolet light and heme-protein-induced peroxidative lipid breakdown in liposomes, as reflected by fluorescence changes: the effect of negative surface charge

The alternative low-spin states of Fe³⁺ and Fe²⁺ cytochrome c induced by SDS or AOT/hexane reverse micelles exhibited the heme group in a less...Full Text Available

2008-05-15

Protein dynamics. Vibrational coupling, spectral broadening mechanisms, and anharmonicity effects in carbonmonoxy heme proteins studied by the temperature dependence of the Soret band lineshape.

The water soluble, photolabile nitrene precursor, azidonaphthalene-2,7-disulfonic acid (ANDS) was encapsulated in small unilamellar, isoelectric (egg PC) or negatively charged (egg PC + dihexadecylphosphate) liposomes. The individual and combined effects of heme-proteins and UV irradiation on the fluorescence of these vesicles under aerobic conditions were studied. Consistent with the catalytic action of heme-proteins on lipid peroxidation and peroxide decomposition, addition of cytochrome c (positively charged) or catalase (negatively charged) to the vesicles elicited immediate formation of a fluorescence band at 470 nm, characteristic of Schiff bases that form from aldehyde byproducts of decomposing hydroperoxides. Ultraviolet irradiation of liposomes caused no significant changes in the fluorescence spectrum, in spite of the radiolysis of ANDS inside the vesicles with consequent formation of nitrene radicals. When isoelectric vesicles were ...

Isoelectric focusing purity criteria and "1H NMR detectable spectroscopic heterogeneity in the major isolated monomer hemoglobins from Glycera dibranchiata

In this work we study the temperature dependence of the Soret band lineshape of the carbonmonoxy derivatives of sperm whale myoglobin, human hemoglobin, and its isolated alpha and beta subunits. To...Full Text Available

1992-08-01

Studies on radiation induced changes in bovine hemoglobin type A

Three major monomeric hemoglobins have been isolated from the erythrocytes of Glycera dibranchiata. Their importance to structure-function studies of heme proteins lies in the fact that they have been shown to possess an exceptional amino acid substitution. In these proteins, the E-7 position is occupied by leucine rather than the more common distal histidine. This substitution alters the polarity of the heme ligand binding environment compared to myoglobin. Due to this, the G. dibranchiata monomer hemoglobins are attracting much attention. However, until now no purity criterion has been developed. Here the authors demonstrate that, for all of the Glycera momomer hemoglobins, multiple line patterns are shown on high-voltage isoelectric focusing (IEF) gels. Most of these lines are shown to be a consequence of heme-related phenomena and can be understood on the basis of changes in oxidation and ligation state of the ...

Expression of fully functional tetrameric human hemoglobin in Escherichia coli

In this paper the structural and functional changes of gamma irradiated bovine hemoglobin are presented. Aqueous solutions/1%/of HbO_2 were irradiated in air with doses ranging from 1 to 4 Mrad. Isoelectric focusing indicated change of the charge of irradiated hemoglobin. The isoelectric point of hemoglobin was displaced towards more acid values with increasing doses, up from 1 Mrad. Fingerprint analysis and peptide column chromatography of irradiated hemoglobin demonstrated disturbances increasing with the dose. These changes were confirmed by amino acid analysis which showed that Cys, Met, Trp, His, Pro and Tyr residues were destroyed or modified following irradiation. At doses exceeding 1 Mrad the irradiated solutions of hemoglobin showed a decrease of heme-heme interaction and an increase of affinity for oxygen. Differences observed in oxygen-dissociation curves seem to be correlated with the radiation induced destruction of amino acid residues which are ...

Effect of lead nitrate on thyroid function on the Indian palm squirrel, Funambulus pennanti (Wroughton)

Synthesis genes encoding the human #alpha#- and #beta#-globin polypeptides have been expressed from a single operon in Escherichia coli. The #alpha#- and #beta#-globin polypeptides associate into soluble tetramers, incorporate heme, and accumulate to >5% of the total cellular protein. Purified recombinant hemoglobin has the correct stoichiometry of #alpha#- and #beta#-globin chains and contains a full complement of heme. Each globin chain also contains an additional methionine as an extension to the amino terminus. The recombinant hemoglobin has a C_4 reversed-phase HPLC profile essentially identical to that of human hemoglobin A_0 and comigrates with hemoglobin A_0 on SDS/PAGE. The visible spectrum and oxygen affinity are similar to that of native human hemoglobin A_0. The authors have also expressed the #alpha#- and #beta#-globin genes separately and found that the expression of the #alpha#-globin gene alone results in a marked decrease in ...

The utility of naphthyl-keratin adducts as biomarkers for jet-fuel exposure.

Some of the known toxic effects of lead in mammals including man are, impaired heme synthesis, anemia, nepatopathy, nephropathy, behavioral disorders and neuropathy. However, very little is known about the effect of lead on endocrine physiology. Some data are available on lead induced impairment of thyroid function in occupationally exposed men and experimental rats. As lead nitrate is largely consumed through water and food, in this study the wild rodents Funambulus pennanti were administered lead through their drinking water and their thyroid structure, radioiodine 131-I percentage uptake and protein bound iodine (PBI) level were assessed.

1987-06-01

Intermediates of radiolytic transformations of 6-aminophenalenone in ethanol

We investigated the association between biomarkers of dermal exposure, naphthyl-keratin adducts (NKA), and urine naphthalene biomarker levels in 105 workers routinely exposed to jet-fuel. A moderate correlation was observed between NKA and urine naphthalene levels (p?=?0.061). The NKA, post-exposure breath naphthalene, and male gender were associated with an increase, while CYP2E1*6 DD and GSTT1-plus (++/+-) genotypes were associated with a decrease in urine naphthalene level (p?

2011-09-30

Intermediate products of radiolytic conversions of 6-aminophenalenone in ethanol

Pulsed radiolysis method is used to study transformations intermediates of 6-aminophenalenone in ethanol. In alkaline medium the main product is radical-anion of 6-aminophenalenone, which optical absorption spectrum contains two bands with maxima at 355 and 400 nm. The particle precursors are e_s, CH_3CHOH and CH_3CHO"- radicals. In neutral and acid medium radical-anions are protonated in reactions with alcohol and hydrogen ions. The resulting H-adduct of 6-aminophenalenone has optical absorption maxima at 350 and 390 nm. Availability of two maxima is related to two various product structures. Molar extinction coefficients of radical-anions and H-adducts of 6-aminophenalenone and rate constants of reactions with their participation are estimated.

1992-01-01

Hydrogen-atom attack on methyl viologen in aqueous solution studied by pulse radiolysis

Intermediate products of the conversions of 6-aminophenalenone in ethanol were investigated by pulse radiolysis. In alkaline medium the main product is the 6-aminophenalenone radical cation, the optical absorption spectrum of which contains two bands with maxima at 355 and 400 nm. The precursors of this particle are e_s, CH_3CHOH and CH_3CHO"- radicals. In neutral and acid medium, radical cations are protonated in reactions with alcohol and hydrogen ions. The H-adduct of 6-aminophenalenone that arises has optical absorption maxima at 350 and 390 nm. The presence of two maxima is due to two different structures of the product. The molar extinction coefficients of the radical anions and H-adducts of 6-aminophenalenone and the rate constants of the reactions involving them were estimated. 6 refs., 4 figs., 2 tabs.

1992-01-01

Alkylaldehyde-bisulfite adducts as cleavable surfactants

Using hydrogen at high pressures of up to 150 bar as an OH scavenger in aqueous MV"2"+ solutions (pH 1) it is possible to differentiate between two kinds of transient formed simultaneously by H-atom attack on methyl viologen. One of them is assigned to an H adduct on the N atom, MV"+H"+, with absorption bands identical to those of the radical cation, MV"+. The MV"+H"+ species deprotonates forming the long-lived radical cation, MV"+. The second type of transient produced is attributed to an H-adduct on the ring carbon, MV"2"+H, decaying by second-order kinetics. The formation of MV"+ by electron transfer from the propan-2-ol radical has been reinvestigated (pH 0 to 7); its absorption spectrum does not change in this pH range. Rate constants and molar extinction coefficients are presented. (U.K.).

1984-01-01

British Library Electronic Table of Contents (United Kingdom)

Alkylaldehyde-bisulfite adducts with octyl, decyl, and dodecyl groups (CnS: n=8,10,12) were synthesized and the surface-active properties of the water-soluble compounds were compared. Exchange of the counter anions of C10S and C12S from sodium to tetramethylammonium solubilized them in water. The latter ammonium salt (C12S-QA) had surface activities as good as a classical surfactant, sodium dodecylsulfate, and dissociated promptly in weakly basic solution at room temperature to be a non-surfactant. It was also found that C12S-QA solubilized a hydrophobic substrate (solid), N,N-dimethyl-3-nitroaniline, in water and then separated it as a precipitate after alkali treatment.

2007-01-01

Active hydrogen by chemical ionization mass spectrometry.

Isotope aided studies of the bioavailability of iron from human diets consumed in Peru

A means of determination of a ctive hydrogen of hydroxyl, carboxyl, sulfhydryl, amino, amido and sulfonamido groups by chemical ionization mass spectrometry using ammonia and trideuterioammonia as reagent gases is described. The method is based on exchange of active hydrogen for deuterium occurring during the chemical ionization process using trideuterioammonia, with comparison of m/z for ammonium adduct [M + NH1]+ and trideuterioammonium adduct [M--nH + nD + ND4]+, or of protonated molecular ion [M + H]+ and deuteronated molecular ion [M--nH + nD + D]+ yielding the number of active hydrogens. Applications have been made to several classes of biologically important compounds. PMID:427257

1979-01-01

Suicide of EMT-6 tumor cells by decays from radioactively-labelled sensitizer adducts

Iron deficiency anaemia is an important health problem in Peru, which affects approximately 25% of the population. The most vulnerable groups are children below 5 years of age and pregnant women, of whom 64% and 53% respectively are anemic. The main reason for this deficiency is inadequate iron intake. Heme iron consumption is very low, and non-heme iron is virtually the only source of iron in the diet. Despite regional differences in food consumption, wheat, salt and sugar are widely consumed in all areas. Wheat is likely to be the most suitable food vehicle for iron fortification due to the processing required. Based on the recent food consumption surveys conducted in Lima by the IIN, we selected examples of typical main meals and measured iron bioavailability in the diet using an extrinsic tag method with 1.5 #mu#Ci of "5"9Fe and 5 #mu#Ci of "5"5Fe as markers. Coffee with bread and butter for breakfast, noodle soup with vegetables, rice with ...

1992-11-16

Pulse radiolysis of aqueous solutions of tetraphenylphosphonium ions

Nitroaromatic radiosensitizers become metabolically bound preferentially to hypoxic cells and at least 10/sup 9/ adducts/cell can be tolerated as non-toxic. EMT-6 tumor cells have been incubated in hypoxia in the presence of /sup 3/H-Misonidazole and /sup 125/I-Azomycin Riboside for various times and the amount of /sup 3/H or /sup 125/I bound/cell was determined. Cells were stored as monolayers at 25"0C for up to 96 hr to accumulate radioactive decays and transferred at various times to 37"0C for colony-forming assays. No radiation inactivation was measured in cells which had incorporated at least 10/sup 6/ /sup 3/H or 10/sup 5/ /sup 125/I atoms. Previous studies had shown that -- 1% of MISO adducts to EMT-6 cells was associated with cellular DNA. These data indicate that the radiation-induced damage produced by these quantities of bound /sup 3/H or /sup 125/I causes little or not cell inactivation. The results of current studies to measure the ...

Levels and distribution of BCNU in GBM tumors following intratumoral injection of DTI-015 (BCNU-ethanol)

The reactions of tetraphenylphosphonium ion (Ar_4P"+) with esub(aq)"-, H atoms and OH radicals have been investigated. The absorption spectra of three transient species were obtained. Ar_4Psup(.) radicals formed by the reaction: Ar_4P"+ + esub(aq)"- #-># Ar_4Psup(.) have a maximum absorption at 305 nm [epsilon _3_0_5 = (9400 +- 300)dm"3mol"-"1cm"-"1] and decays by second-order kinetics with the rate constant 2k = (2.7 +- 0.4) x 10"9dm"3mol"-"1s"-"1. H atoms and OH radicals form transient adducts to the phenyl groups of the Ar_4P"+ ion with the rate constants of (1.5 +- 0.3) x 10"9 dm"3mol"-"1s"-"1 and (3.0 +- 0.3) x 10"9dm"3mol"-"1s"-"1, respectively. Both adducts have broad absorption spectra at 300 approximately 380 nm (lambdasub(max) = 340 nm) with the molar extinction coefficients epsilonsub(340) = 5400 +- 300 dm"3mol"-"1cm"-"1 for the H adduct and epsilonsub(340) = 3500 +- 200 dm"3mol"-"1cm"-"1 for the OH ...

1976-01-01

Association between meniscal tears and the peak external knee adduction moment and foot rotation during level walking in postmenopausal women without knee osteoarthritis: a cross-sectional study

The alkylation products formed by in vitro treatment of DNA with tritium-labeled 1,3-bis(2-chloroethyl)-1-nitrosourea (³H-BCNU) were identified and quantified. Twelve adducts were resolved...Full Text Available

2007-01-01

Leishmania major ascorbate peroxidase overexpression protects cells against reactive oxygen species-mediated cardiolipin oxidation

IntroductionMeniscal injury is a risk factor for the development and progression of knee osteoarthritis, yet little is known about risk factors for meniscal pathology. Joint loading...Full Text Available

2008-01-01

British Library Electronic Table of Contents (United Kingdom)

Heme peroxidases are a class of multifunctional redox-active proteins found in all organisms. We recently cloned, expressed, and characterized an ascorbate peroxidase from Leishmania major (LmAPX) that was capable of detoxifying hydrogen peroxide. Localization studies using green fluorescent protein fusions revealed that LmAPX was localized within the mitochondria by its N-terminal signal sequence. Subcellular fractionation analysis of the cell homogenate by the Percoll density-gradient method and subsequent Western blot analysis with anti-LmAPX antibody further confirmed the mitochondrial localization of mature LmAPX. Submitochondrial fractionation analysis showed that the mature enzyme (?3.6?kDa shorter than the theoretical value of the whole gene) was present in the intermembrane space ...

2008-01-01

1 2 3 4

Preconcentration and determination of trace amounts of lead (II) as thenoyltrifluoroacetone complex with dibenzo-18-crown-6 by synergistic extraction and atomic absorption spectrometry

Hydroxyl radical formation by UV-irradiated epidermal cells

A new method for the preconcentration and determination of trace amounts of lead at the {mu}g/L level in natural waters has been established based on the formation of the thenoyltrifluoroacetone (TTA) complex with dibenzo-18-crown-6 (DB18C6) by means of synergistic extraction and back-extraction combined with atomic absorption spectrometry (AAS). The effect of various factors (synergism with TTA and DB18C6, shaking time, preconcentration factor, composition of the extracted species, and foreign ions etc.) on the extraction and back-extraction of lead has been investigated in detail. The lead-TTA chelate in o-dichlorobenzene forms a stable adduct with DB18C6 as Pb(TTA){sub 2} DB18C6. The stability constant ({beta}) of the adduct determined by curve fitting method was log {beta} = 4.2. The amount of lead in natural waters such as tap water (Kanazawa University) and Kakehashi river (Komatsu City) determined by the present method was found to be ...

1998-07-01

Hepatic aflatoxin B1-DNA adducts and TP53 mutations in patients with hepatocellular carcinoma despite low exposure to aflatoxin B1 in southern Japan

To elucidate the mechanism of sunlight-induced skin damage, guinea pigs exposed to UV light (280-320 nm, UV B, 4J/cm"2) and a homogenate of the epidermis was examined by means of the thiobarbituric acid (TBA) test. Three hours after the exposure, TBA-malondialdehyde adducts had increased while glutathione reductase activity had decreased, indicating lipid peroxidation. To detect the initial species, spin trapping with 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) was applied to a suspension of illuminated epidermal cells (0.5 J/cm"2). An ESR signal obtained only with irradiation comprised a 1 : 2 : 2 : 1 quartet [a (N) =a (#beta#H) =1.49 mT] attributable to a spin adduct of hydroxyl radicals. These results suggest that sunlight exposure of skin may lead to hydroxyl radical generation and simultaneous lipid peroxidation. (author).

British Library Electronic Table of Contents (United Kingdom)

Abstract Background & aims: Hepatitis B or C virus infection is considered to be the main cause of hepatocellular carcinoma (HCC) in Japan. Aflatoxin B1 (AFB1) is a carcinogen associated with HCC in regions with high exposure. Mutations in codon 249, exon 7 are a hallmark of AFB1 exposure. Therefore, to clarify the role of AFB1 in hepatocarcinogenesis, we examined AFB1-DNA in liver tissue and sequenced TP53 in Japanese patients with HCC. Methods: Hepatocyte AFB1-DNA adducts were determined immunohistochemically and direct sequencing of TP53 was done to determine mutations in 188 of 279 patients who underwent hepatic resection for HCC. We assessed hepatitis C virus antibodies (HCV Ab) and HBSAg expression; patients without either were defined as having non-B non-C hepatocellular carcinoma (...

2011-01-01

Thermally cleavable surfactants

Thermally cleavable surfactants

Two new surfactant molecules are reported which contain thermally labile Diels-Alder adducts connecting the polar and non-polar sections of each molecule. The two surfactants possess identical non-polar dodecyl tail segments but exhibit different polar headgroups. The surfactants become soluble in water when anionic salts are formed through the deprotonation of the surfactant headgroups by the addition of potassium hydroxide. When either surfactant is exposed to temperature above about 60.degree. C., the retro Diels-Alder reaction occurs, yielding hydrophilic and hydrophobic fragments or the aqueous solutions of the surfactants subsequently exhibit loss of all surface-active behavior.

2009-09-29

Thermally cleavable surfactants

2009-11-24

Extraction of lithium from neutral salt solutions with fluorinated #beta#-diketones

Two new surfactant molecules are reported which contain thermally labile Diels-Alder adducts connecting the polar and non-polar sections of each molecule. The two surfactants possess identical non-polar dodecyl tail segments but exhibit different polar headgroups. The surfactants become soluble in water when anionic salts are formed through the deprotonation of the surfactant headgroups by the addition of potassium hydroxide. When either surfactant is exposed to temperature above about 60.degree. C., the retro Diels-Alder reaction occurs, yielding hydrophilic and hydrophobic fragments and the aqueous solutions of the surfactants subsequently exhibit loss of all surface-active behavior.

2006-04-04

Effect of repeated benzene inhalation exposures on benzene metabolism, binding to hemoglobin, and induction of micronuclei

Lithium was selectively extracted from near-neutral aqueous solutions of alkali metal salts. The mechanism by which this was achieved involves the formation of the trioctylphosphine oxide adduct of a lithium chelate of a fluorinated #beta#-diketone, which is then readily extractable into an organic diluent. High separation factors were obtained from sodium, potassium, rubidium, and cesium. The selectivity of the fluorinated #beta#-diketones for lithium over the alkaline earths was found to be poor. A suggested general flowsheet for the recovery of lithium from a salt brine concentrate is included. (author).

Carbon felt-based bioelectrocatalytic flow-through detectors: Highly sensitive amperometric determination of H2O2 based on a direct electrochemistry of covalently modified horseradish peroxidase using cyanuric chloride as a linking agent

Metabolism of benzene is thought to be necessary to produce the toxic effects, including carcinogenicity, associated with benzene exposure. To extrapolate from the results of rodent studies to potential health risks in man, one must know how benzene metabolism is affected by species, dose, dose rate, and repeated versus single exposures. The purpose of our studies was to determine the effect of repeated inhalation exposures on the metabolism of [14C]benzene by rodents. Benzene metabolism was assessed by characterizing and quantitating urinary metabolites, and by quantitating 14C bound to hemoglobin and micronuclei induction. F344/N rats and B6C3F1 mice were exposed, nose-only, to 600 ppm benzene or to air (control) for 6 hr/day, 5 days/week for 3 weeks. On the last day, both benzene-pretreated and control animals were exposed to 600 ppm, 14C-labeled benzene for 6 hr. Individual benzene metabolites in urine collected for 24 hr after the exposure were analyzed. There was a significant ...

British Library Electronic Table of Contents (United Kingdom)

Horseradish peroxidase (HRP) was chemically modified using cyanuric chloride (CC) as a linking agent onto a carbon felt (CF), which is a microelectrode ensemble of micro carbon fiber (>7mm, diameter) with a random three-dimensional structure. The resulting HRP-modified CF (HRP-ccCF) exhibited well-defined redox waves based on the HRP heme Fe^I^I^I/Fe^I^I redox couple at -0.23V vs. Ag/AgCl (at pH 7.0), while the HRP-adsorbed CF (HRP-CF) showed no apparent redox couple in the same potential range, indicating that the chemical modification of HRP via CC facilitated the direct electron transfer (DET) between HRP and CF. The apparent heterogeneous electron transfer rate constant ks was estimated to be 35s^-^1. Cyclic voltammetry and electrochemical impedance spectroscopy revealed that the inter...

2011-01-01

Antihemostatic molecules from saliva of blood-feeding arthropods.

Unidirectional growth, linear and nonlinear optical, dielectric and mechanical properties of organic adduct of L-tartaric acid nicotinamide

The ability to feed on vertebrate blood has evolved many times in various arthropod clades. Each time this trait evolves, novel solutions to the problem posed by vertebrate hemostasis are generated. Consequently, saliva of blood-feeding arthropods has proven to be a rich source of antihemostatic molecules. Vasodilators include nitrophorins (nitric oxide storage and transport heme proteins), a variety of peptides that mimic endogenous vasodilatory neuropeptides, and proteins that catabolize or sequester endogenous vasoconstrictors. A variety of platelet aggregation inhibitors antagonize platelet responses to wound-generated signals, including ADP, thrombin, and collagen. Anticoagulants disrupt elements of both the intrinsic and extrinsic pathways. Molecular approaches (termed 'sialomics') to characterize the full inventory of mRNAs transcribed in salivary glands have revealed a surprising level of complexity within a single species. Multiple salivary proteins may be ...

2005-01-01

Report on NCI symposium: comparison of mechanisms of carcinogenesis by radiation and chemical agents. II. Cellular and animal models

An attempt has been made to grow L-tartaric acid nicotinamide (LTN); a complex of tartaric acid, by employing a modified unidirectional method. The crystalline structure and quality are investigated by single crystal XRD and rocking curve studies. The linear and nonlinear optical properties are studied by UV-vis-NIR spectral analysis, SHG test, phase matching and laser induced damage threshold measurement. For comparison, parallel growth of the crystal was carried out by conventional method and the properties of the LTN samples grown by the conventional and unidirectional methods are investigated. The mechanical, photoconductivity and dielectric behavior of LTN crystals are also investigated.

2011-03-15

N-acetoxy-N-2-acetylaminofluorene induced frameshift mutations: a comparison between the DNA modification spectrum and the mutation spectrum

The point at which the common final pathway for induction of cancer by chemical carcinogens and ionizing radiation has not been identified. Although common molecular targets are suggested by recent findings about the role of oncogenes, the mechanism by which the deposition of radiation energy and the formation of adducts or other DNA lesions induced by chemicals affects the changes in the relevant targets may be quite different. The damage to DNA that plays no part in the transformation events, but that influences the stability of the genome, and therefore, the probability of subsequent changes that influence tumorigenesis may be more readily induced by some agents than others. Similarly, the degree of cytotoxic effects that disrupt tissue integrity and increase the probability of expression of initiated cells may be dependent on the type of carcinogen. Also, evidence was presented that repair of the initial lesions could be demonstrated after exposure to low-LET ...

1984-05-20

Ligand Tuning in Asymmetric Hydrovinylation of 1,3-Dienes. A Stereoselective Route to either Steroid-C20 (S) or -C20 (R) Derivatives

We describe the analysis of forward mutations induced in the tetracycline resistance gene of the plasmid pBR322 by directing the reaction of the carcinogen N-acetoxy-N-2-acetylaminofluorene (N-AcO-AAF) to a small restriction fragment (BamHI, SalI) that is located in the proximal part of the antibiotic-resistance gene. Mutant plasmids obtained both in wild type and excision repair deficient (uvrA) bacterial cells are compared. Preliminary data showing the distribution of the -AAF adducts along this restriction fragments are discussed in relation to the observed spectrum of mutations. 20 references, 4 figures.

Simulation of the experimental crystal field splitting pattern of a mono tetrahydrofuran adduct derived from tris(bis(trimethylsilyl)amido)neodymium(III)

1,3-Dienes derived from steroidal D-ring C17-ketones undergo Ni(II)-catalyzed hydrovinylation to give 1,2- or 1,4-addition of ethylene. Using finely tuned phosphoramidite ligands it is possible to synthesize either the C20 (R)- or the C20 (S)-derivatives without mutual contamination. The proportion of the 1,4-adduct, which is also formed stereoselectively, can be minimized by optimizing the reaction conditions. Since the two alkenes in the resultant dienes have differing steric demands for many potential reactions, and are ideally juxtaposed for further D-ring functionalization, these intermediates could be useful for the preparation of biologically important compounds such as vitamin D analogs and various antitumor steroidal glycosides.

2008-06-21

Separation and determination of cadmium and zinc as their thenoyltrifluoroacetone complexes with dibenzo-18-crown-6 by means of synergistic extraction and atomic absorption spectrometry

Full text: In case of lanthanide (Ln) compounds the bis(trimethylsilyl)amido (btmsa) ligand is considered as a steric and electronic equivalent of the bis(trimethylsilyl)methanido (btmsm) group . Because of their extreme air and moisture sensitivity the chemistry of Ln(btmsm)_3 is very poor, whereas that of comparatively stable Ln(btmsa)_3 is much more developed. As we wish to extend the chemistry of Ln(btmsm)_3 and plan to derive and to parameterize the crystal field (CF) splitting patterns of the target molecules, it is recommended to study in advance the electronic structures of the corresponding compounds derived from Ln(btmsa)_3 . Beside (btmsa)_3 Nd(m-Cl)Li(THF)_3 a number of mono base adducts [(btmsa)_3 Ln.B] with sterically less demanding bases such as OPPh_3 , NCtBu or CNtBu have been described and were partly structurally characterized. Considering only the immediately coordinating atoms, the effective CF is of C_3_v symmetry. According to recent ...

1998-10-25

Reactivity differences of hydroxyl radicals and hydrated electrons in destructing azo dyes

A new method for the separation and determination of trace amounts of cadmium and zinc in water as their thenoyltrifluoroacetone (TTA) complexes with dibenzo-18-crown-6 (DB18C6) in o-dichlorobenzene has been established by means of synergistic extraction and back-extraction combined with atomic absorption spectrometry. The effect of various factors (synergism with TTA and DB18C6, shaking time, composition of the extracted species, and mutual separation etc.) on the extraction and back-extraction of cadmium and zinc has been in- vestigated. When the mixtures were extracted for 4 min at pH 4.9, only zinc was extracted quantitatively, whereas cadmium remained in the aqueous phase. After the phases were separated, cadmium was again extracted quantitatively at pH 7.5. Then, the two phases were each shaken with 0.05-0.1 mol/l HCl in order to back-extract cadmium and zinc from the organic phases; the ions were determined individually by atomic absorption spectrometry. In the process cadmium ...

1997-01-01

Planning and interpreting cement bond logs; Implementation of an expert system

The high-energy radiation-induced degradation of an H-acid derivative azo dye, Apollofix-Red SF-28 (AR-28) was studied in aqueous solution by using pulse radiolysis with kinetic spectroscopic detection for transient measurements. Gamma radiolysis with UV-VIS spectroscopy and gradient ionpair HPLC separation with diode array detection were applied for following the destruction of AR-28 and measuring the products. The reactions of hydrated electron (e_a_q "-) and hydroxyl ("#centre dot#OH) radical were investigated separately. "#centre dot#OH reacts with the unsaturated bonds of the molecule. In the further reactions of the "#centre dot#OH adduct radicals, the AR-28 molecules partly reform with a slightly modified structure. The products formed in the first reaction of "#centre dot#OH and AR-28 molecules have also high reactivity towards the "#centre dot#OH radicals. For these reasons the efficiency of "#centre dot#OH radicals in discolouration of the solution is ...

Nonenzymatic glycosylation of human hemoglobin at multiple sites

The Cement Bond Log Advisor is an expert system being developed to assist users in the design, evaluation, and interpretation of cement bond logs (CBL's). CBL's are produced by sonic tools run after the casing is cemented in a well to determine how well the cement is bonded to the casing and formation and whether a cement squeeze jog should be attempted. During the development of program, two particular challenges were encountered and resolved in ways that might be of general interest to developers of expert system applications for the petroleum industry. The first challenge was to find an efficient and effective method for guiding the user in correlating and interpreting the relationships between multiple sources of continuous visual data (the various waveforms making up the log output). Second, the nomographs, which correlate log amplitudes with cement compressive strength and are used in the log interpretation, were derive from empirical data and were not readily ...

1991-07-01

New horizons of zeolite supported catalysts

The most abundant minor hemoglobin component of human hemolysate is Hb A1c, which has glucose bound to the N-terminus of the beta chain by a ketoamine linkage. Hb A1c is formed slowly and continuously throughout the 120 day lifespan of the red cell. It can be synthesized in vitro by incubating purified hemoglobin with 14C-glucose. Other minor components, Hb A1a1 and Hb A1a2 are adducts of sugar phosphates at the N-terminus of the beta chain. Hb A1b contains an unidentified nonphosphorylated sugar at the beta N-terminus. In addition, a significant portion of the major hemoglobin component (Hb Ao) is also glycosylated by a glucose ketoamine linkage at other sites on the molecule, including the N-terminus of the alpha chain and the epsilon-amino group of several lysine residues on both the alpha and the beta chains. The results indicate that the interaction of glucose and hemoglobin is rather nonspecific and suggests that other proteins are modified in a similar ...

Inhibition of tau fibrillization by oleocanthal via reaction with the amino groups of tau

This paper reports on the superiority of zeolites over amorphous solids which is well documented for solid acid catalysts of industrial use. Crystalline supports, likewise, open attractive perspectives for catalysis by metals, alloys, and ligated metal clusters. Size and location of clusters can be controlled by careful design of the preparation conditions. Pore dimensions control the access of reactants to active sites and escape paths for products. Cage dimensions determine which transition states can be attained; window apertures are functional in isolating metal clusters from each other, thus preventing ther coalescence and growth. The ship-in-a-bottle method permits deisgn of fairly large active complexes entrapped in zeolite cages. Orientation of non-spherical molecules in a zeolite proe helps to direct their collision with a metal particle to the head on mode; however, isolated Pt atoms hidden in niches of the pore walls can attack passing molecules at their soft flanks. ...

1992-04-05

1 2 3 4

Biophysical analysis of DNA modified by 1,2-diaminocyclohexane platinum(II) complexes

Tau is a microtubule-associated protein that promotes microtubule assembly and stability. In Alzheimer's disease and related tauopathies, tau fibrillizes and aggregates into neurofibrillary tangles. Recently, oleocanthal isolated from extra virgin olive oil was found to display non-steroidal anti-inflammatory activity similar to ibuprofen. Since our unpublished data indicates an inhibitory effect of oleocanthal on A? fibrillization, we reasoned that it might inhibit tau fibrillization as well. Herein we demonstrate that oleocanthal abrogates fibrillization of tau by locking tau into the naturally unfolded state. Using PHF6 consisting of the amino acid residues VQIVYK, a hexapeptide within the third repeat of tau that is essential for fibrillization, we show that oleocanthal forms an adduct with the lysine via initial Schiff base formation. Structure and function studies demonstrate that the two aldehyde groups of oleocanthal are required for the inhibitory ...

2009-06-15

Biomonitoring for creosote and pentachlorophenol in nearby residents of a wood treatment plant

Modification of DNA and double-stranded deoxyoligonucleotides with antitumor 1,2-diamino-cyclohexanedinitroplatinum(II) (Pt-dach) complexes was investigated with the aid of physico-chemical methods and chemical probes of nucleic acid conformation. The three Pt-dach complexes were used which differed in isomeric forms of the dach non-leaving ligand-Pt(1R,2R-dach), Pt(1S,2S-dach) and Pt(1R,2S-dach) complexes. The latter complex has lower antitumor activity than the other two Pt-dach complexes. Pt(1R,2S-dach) complex exhibits the slowest kinetics of its binding to DNA and of the conversion of monofunctional binding to bifunctional lesions. The anomalously slow electrophoretic mobility of multimers of the platinated and ligated oligomers suggests that bifunctional binding of Pt-dach complexes to a d(GG) site within double-stranded oligonucleotides induces bending of the oligomer. It is proposed that different effects of the Pt-dach complexes on DNA observed in this work arise mainly from a ...

1992-01-25

The CYP2A3 gene product catalyzes coumarin 7-hydroxylation in human liver microsomes

Contaminated wood treatment sites can result in adverse health effects to nearby residents. Environmental exposure can be estimated by measuring concentrations of pollutants in air, water, food, or wipe tests. This environmental exposure value can be used as a surrogate to estimate individual exposure. The objective of this study was to determine whether or not pentachlorophenol (PCP) could be found in potentially exposed residents and if the dioxin levels are consistent with PCP exposure. A further objective of the study was to determine whether or not PAH-DNA adducts could be found in the potentially exposed residents. We present results of biomonitoring studies in residents living near a wood treatment plant that used coal-derived creosote and PCP to process and treat wood for over 100 years. The plant was built in 1904 and used creosote and PCP. Creosote is a complex mixture that contains numerous polycyclic aromatic hydrocarbons (PAHs). PCP is contaminated ...

2004-09-15

The CYP2A3 gene product catalyzes coumarin 7-hydroxylation in human liver microsomes

Three cDNAs, designated IIA3, IIA3v, and IIA4, coding for P450s in the CYP2A gene subfamily were isolated from a {lambda}gt11 library prepared from human hepatic mRNA. Only three nucleotide differences and a single amino acid difference, Leu{sup 160}{yields}His, were found between IIA3 and IIA3v, indicating that they are probably allelic variants. IIA4 displayed 94% amino acid similarity with IIA3 and IIA3v. The three cDNAs were inserted into vaccinia virus, and recombinant viruses were used to infect human hepatoma Hep G2 cells. Only IIA3 was able to produce an enzyme that had a reduced CO-bound spectrum with a {lambda}{sub max} at 450 nm. This expressed enzyme was able to carry out coumarin 7-hydroxylation and ethoxycoumarin O-deethylation. cDNA-expressed IIA3v and IIA4 failed to incorporate heme and were enzymatically inactive. Analysis of IIA proteins in human liver microsomes, using antibody against rat IIA2, revealed two proteins of 49 and 50 kDa, the former ...

1990-02-06

Increased oxidative stress and antioxidant expression in mouse keratinocytes following exposure to paraquat

Three cDNAs, designated IIA3, IIA3v, and IIA4, coding for P450s in the CYP2A gene subfamily were isolated from a #lambda#gt11 library prepared from human hepatic mRNA. Only three nucleotide differences and a single amino acid difference, Leu"1"6"0#->#His, were found between IIA3 and IIA3v, indicating that they are probably allelic variants. IIA4 displayed 94% amino acid similarity with IIA3 and IIA3v. The three cDNAs were inserted into vaccinia virus, and recombinant viruses were used to infect human hepatoma Hep G2 cells. Only IIA3 was able to produce an enzyme that had a reduced CO-bound spectrum with a #lambda#_m_a_x at 450 nm. This expressed enzyme was able to carry out coumarin 7-hydroxylation and ethoxycoumarin O-deethylation. cDNA-expressed IIA3v and IIA4 failed to incorporate heme and were enzymatically inactive. Analysis of IIA proteins in human liver microsomes, using antibody against rat IIA2, revealed two proteins of 49 and 50 kDa, the former of ...

1990-02-01

Hot atom labeling of myoglobin and hemoglobin and biophysical studies of oxygen and CO binding to carp hemoglobin

Paraquat (1,1'-dimethyl-4,4'-bipyridinium) is a widely used herbicide known to induce skin toxicity. This is thought to be due to oxidative stress resulting from the generation of cytotoxic reactive oxygen intermediates (ROI) during paraquat redox cycling. The skin contains a diverse array of antioxidant enzymes which protect against oxidative stress including superoxide dismutase (SOD), catalase, glutathione peroxidase-1 (GPx-1), heme oxygenase-1 (HO-1), metallothionein-2 (MT-2), and glutathione-S-transferases (GST). In the present studies we compared paraquat redox cycling in primary cultures of undifferentiated and differentiated mouse keratinocytes and determined if this was associated with oxidative stress and altered expression of antioxidant enzymes. We found that paraquat readily undergoes redox cycling in both undifferentiated and differentiated keratinocytes, generating superoxide anion and hydrogen peroxide as well as increased protein oxidation which ...

2008-09-15

The ATG1/ATG13 Protein Kinase Complex Is Both a Regulator and a Target of Autophagic Recycling in Arabidopsis.

Human Hb, the monomeric Hb of Glycera dibranchiata and horse Mb were modified by replacement of the protoheme with 2,4-dibromodeuteroheme. Following neutron capture by "7"9Br and "8"1Br, the locations of radioactive Br were determined. Although human Hb had approximately four times the mass and volume of the other proteins, about 9% of the activated Br was inserted into each of the three globins. These results suggest that the insertion is short-range (within 15 angstrom) and that this method could be used to label target sites in various proteins and other biological structures. Carp Hb's containing proto-, meso-, deutero- and dibromoheme were prepared. Kinetic and thermodynamic parameters for oxygen and CO binding were determined at Ph 6 (+IHP) (T-state, low-affinity protein) and Ph 9 (R-state, high-affinity protein). Parameters for the binding of oxygen and CO were related to the properties of the four hemes to estimate the inductive and steric factors in the ...

Propanil-induced methemoglobinemia and hemoglobin binding in the rat

Autophagy is an intracellular recycling route in eukaryotes whereby organelles and cytoplasm are sequestered in vesicles, which are subsequently delivered to the vacuole for breakdown. The process is induced by various nutrient-responsive signaling cascades converging on the Autophagy-Related1 (ATG1)/ATG13 kinase complex. Here, we describe the ATG1/13 complex in Arabidopsis thaliana and show that it is both a regulator and a target of autophagy. Plants missing ATG13 are hypersensitive to nutrient limitations and senesce prematurely similar to mutants lacking other components of the ATG system. Synthesis of the ATG12-ATG5 and ATG8-phosphatidylethanolamine adducts, which are essential for autophagy, still occurs in ATG13-deficient plants, but the biogenesis of ATG8-decorated autophagic bodies does not, indicating that the complex regulates downstream events required for autophagosome enclosure and/or vacuolar delivery. Surprisingly, levels of the ATG1a and ATG13a ...

2011-10-01

Products of the Benzene + O(3P) Reaction

Administration of [ring-U-14C]propanil (3,4-dichloropropionanilide) to male Sprague-Dawley rats (30, 100, and 300 mg/kg, ip) increased the formation of methemoglobin at the two highest doses. Following a propanil dose of 100 mg/kg, methemoglobin formation attained a maximum level of 5% by 1.5 hr and declined to normal levels (approximately 2.5%) by 12 hr. Hemoglobin binding attained a maximum level of 50 pmol/mg protein by 12 hr, and remained constant for 24 hr. Following a propanil dose of 300 mg/kg, methemoglobin formation attained a maximum level of 24% by 4.5 hr, and declined to a level of 5% by 24 hr. Hemoglobin binding attained a maximum level of 425 pmol/mg protein by 12 hr, and remained constant for 24 hr. Hemoglobin binding was also detected at the lowest propanil dose (10 pmol/mg protein) even though methemoglobin formation was not observed. HPLC analysis of alkaline-treated hemoglobin from propanil-treated rats indicated the presence of one radiolabeled compound with the ...

Kinetics and product analysis of bromium-initiated gas-phase oxidation of {alpha}, {beta}-unsaturated carbonyls; Kinetik und Produktanalyse der brominitiierten Gasphasenoxidation von {alpha}, {beta}-ungesaettigten Carbonylen

The gas-phase reaction of benzene with O(3P) is of considerable interest for modeling of aromatic oxidation, and also because there exist fundamental questions concerning the prominence of intersystem crossing in the reaction. While its overall rate constant has been studied extensively, there are still significant uncertainties in the product distribution. The reaction proceeds mainly through the addition of the O atom to benzene, forming an initial triplet diradical adduct, which can either dissociate to form the phenoxy radical and H atom, or undergo intersystem crossing onto a singlet surface, followed by a multiplicity of internal isomerizations, leading to several possible reaction products. In this work, we examined the product branching ratios of the reaction between benzene and O(3P) over the temperature range of 300 to 1000 K and pressure range of 1 to 10 Torr. The reactions were initiated by pulsed-laser photolysis of NO2 in the presence of benzene and ...

2009-12-21

Glycolate adsorption at gold and platinum electrodes: A theoretical and in situ spectroelectrochemical study

The purpose of the present study was to examine reactions between bromium atoms with {alpha}, {beta}-unsaturated carbonyls. Acrolein, methacrolein, and methyl vinyl zetone were chosen as representatives of this family. The latter two compounds, beside formaldehyde, belong to the main products of atmospheric oxidation of isoprene and have been detected in the troposphere at concentrations of up to almost 1 ppb. It is known that alkenes react with bromium via addition to form an instable adduct. This product can either decompose again into its educts or react with molecular oxygen. The aim of the study was to determine the velocities of the reactions between the three {alpha}, {beta}-unsaturated carbonyls and bromium and to clarify the involved reaction mechanisms by means of kinetic experiments and product analyses. (orig./SR) [Deutsch] In dieser Arbeit wurde die Reaktion von Bromatomen mit {alpha}, {beta}-ungesaettigten Carbonylen untersucht. Ausgewaehlt wurden ...

1997-03-01

Chemopreventive effects of Furan-2-yl-3-pyridin-2-yl-propenone against 7,12-dimethylbenz[a]anthracene-inducible genotoxicity

The adsorption of glycolate anions at sputtered gold thin-film electrodes was studied in perchloric acid solutions by cyclic voltammetry experiments combined with in situ Surface Enhanced Raman Scattering (SERS) and Surface Enhanced Infrared Reflection Absorption Spectroscopy under attenuated total reflection conditions (ATR-SEIRAS). Theoretical harmonic vibrational frequencies and band intensities obtained from B3LYP/LANL2DZ,6-31+G(d) calculations for glycolate species adsorbed on Au clusters with (1 1 1) orientation were used to interpret the experimental spectra. Vibrational data confirm the bidentate bonding of glycolate anions through the oxygen atoms of the carboxylate group, in a bridge configuration with the OCO plane perpendicular to the metal surface. The DFT calculations show no significant effect of the total charge of the metal cluster-adsorbate adduct on the vibrational frequencies of adsorbed glycolate species. The infrared experimental study is ...

2010-02-15