Academic literature on the topic '3-glutathionyl-1'

A triple mutant of rat liver glutathione S-transferase 3-3 that has all three cysteine residues replaced with serine (CallS) and a quadruple mutant with a Tyr-115 to phenylalanine substitution on CallS (CallSY115F) were reacted with 2-(S-glutathionyl)-3,5,6-trichloro-1,4-benzoquinone (GS-1,4-TCBQ). The modified proteins were analysed on a triple-quadrupole mass spectrometer equipped with an electrospray ionization source. At an enzyme: GS-1,4-TCBQ ratio of 1:10, the enzymes were modified at multiple sites. Covalent attachment of a single inhibitor on to the protein was achieved by lowering the enzyme: GS-1,4-TCBQ ratio to 1:1. Results from m.s. analyses suggest that the inhibitor on the CallSY115F mutant exists as a glutathionyl dichlorobenzoquinone derivative. The modifiers of the CallS mutants are glutathionyl monochlorobenzoquinone derivatives. Therefore, GS-1,4-TCBQ reacts at a single site on CallSY115F, but probably cross-links two regions on wild-type and CallS mutant. To confirm our observation, CallS was modified with 1-chloro2,4-dinitrobenzene, which specifically labels Tyr-115, before reacting with GS-1,4-TCBQ. The inhibitor formed a glutathionyl dichlorobenzoquinone adduct on the dinitrophenyl-CallS mutant. In addition, the benzoquinone derivative on the protein can be partially removed by 1-chloro-2,4-dinitrobenzene. Peptide mapping and sequencing analysis of the GS-1,4-TCBQ-modified CallS mutant revealed that the C-terminal 16-amino-acid fragment is labelled. Molecular modelling suggests the C(5) and C(6) on the benzoquinone ring of the inhibitor interact with the oxygen atoms of Tyr-115 and Ser-209 respectively.

ABSTRACT A glutathione S-transferase (GST) with activity toward 1,2-epoxy-2-methyl-3-butene (isoprene monoxide) andcis-1,2-dichloroepoxyethane was purified from the isoprene-utilizing bacterium Rhodococcus sp. strain AD45. The homodimeric enzyme (two subunits of 27 kDa each) catalyzed the glutathione (GSH)-dependent ring opening of various epoxides. At 5 mM GSH, the enzyme followed Michaelis-Menten kinetics for isoprene monoxide and cis-1,2-dichloroepoxyethane, withV max values of 66 and 2.4 μmol min−1 mg of protein−1 andKm values of 0.3 and 0.1 mM for isoprene monoxide and cis-1,2-dichloroepoxyethane, respectively. Activities increased linearly with the GSH concentration up to 25 mM.1H nuclear magnetic resonance spectroscopy showed that the product of GSH conjugation to isoprene monoxide was 1-hydroxy-2-glutathionyl-2-methyl-3-butene (HGMB). Thus, nucleophilic attack of GSH occurred on the tertiary carbon atom of the epoxide ring. HGMB was further converted by an NAD+-dependent dehydrogenase, and this enzyme was also purified from isoprene-grown cells. The homodimeric enzyme (two subunits of 25 kDa each) showed a high activity for HGMB, whereas simple primary and secondary alcohols were not oxidized. The enzyme catalyzed the sequential oxidation of the alcohol function to the corresponding aldehyde and carboxylic acid and followed Michaelis-Menten kinetics with respect to NAD+ and HGMB. The results suggest that the initial steps in isoprene metabolism are a monooxygenase-catalyzed conversion to isoprene monoxide, a GST-catalyzed conjugation to HGMB, and a dehydrogenase-catalyzed two-step oxidation to 2-glutathionyl-2-methyl-3-butenoic acid.

Understanding the cellular effects of flavonoid metabolites is important for predicting which dietary flavonoids might be most beneficial in vivo. Here we investigate the bioactivity in dermal fibroblasts of the major reported in vivo metabolites of quercetin, i.e. 3′-O-methyl quercetin, 4′-O-methyl quercetin and quercetin 7-O-β-d-glucuronide, relative to that of quercetin, in terms of their further metabolism and their resulting cytotoxic and/or cytoprotective effects in the absence and presence of oxidative stress. Uptake experiments indicate that exposure to quercetin led to the generation of two novel cellular metabolites, one characterized as a 2′-glutathionyl quercetin conjugate and another product with similar spectral characteristics but 1 mass unit lower, putatively a quinone/quinone methide. A similar product was identified in cells exposed to 3′-O-methyl quercetin, but not in the lysates of those exposed to its 4′-O-methyl counterpart, suggesting that its formation is related to oxidative metabolism. There was no uptake or metabolism of quercetin 7-O-β-d-glucuronide by fibroblasts. Formation of oxidative metabolites may explain the observed concentration-dependent toxicity of quercetin and 3′-O-methyl quercetin, whereas the formation of a 2′-glutathionyl quercetin conjugate is interpreted as a detoxification step. Both O-methylated metabolites conferred less protection than quercetin against peroxide-induced damage, and quercetin glucuronide was ineffective. The ability to modulate cellular toxicity paralleled the ability of the compounds to decrease the level of peroxide-induced caspase-3 activation. Our data suggest that the actions of quercetin and its metabolites in vivo are mediated by intracellular metabolites.

ABSTRACT The genes involved in isoprene (2-methyl-1,3-butadiene) utilization in Rhodococcus sp. strain AD45 were cloned and characterized. Sequence analysis of an 8.5-kb DNA fragment showed the presence of 10 genes of which 2 encoded enzymes which were previously found to be involved in isoprene degradation: a glutathioneS-transferase with activity towards 1,2-epoxy-2-methyl-3-butene (isoI) and a 1-hydroxy-2-glutathionyl-2-methyl-3-butene dehydrogenase (isoH). Furthermore, a gene encoding a second glutathioneS-transferase was identified (isoJ). TheisoJ gene was overexpressed in Escherichia coliand was found to have activity with 1-chloro-2,4-dinitrobenzene and 3,4-dichloro-1-nitrobenzene but not with 1,2-epoxy-2-methyl-3-butene. Downstream of isoJ, six genes (isoABCDEF) were found; these genes encoded a putative alkene monooxygenase that showed high similarity to components of the alkene monooxygenase fromXanthobacter sp. strain Py2 and other multicomponent monooxygenases. The deduced amino acid sequence encoded by an additional gene (isoG) showed significant similarity with that of α-methylacyl-coenzyme A racemase. The results are in agreement with a catabolic route for isoprene involving epoxidation by a monooxygenase, conjugation to glutathione, and oxidation of the hydroxyl group to a carboxylate. Metabolism may proceed by fatty acid oxidation after removal of glutathione by a still-unknown mechanism.

The effect of ultrasound (20 kHz, 153 μm) on the prefermentation extraction mechanisms in Sauvignon Blanc grapes was studied, focusing on 3-mercaptohexan-1-ol (3MH) and 4-mercapto-4-methyl-pentan-2-one (4MMP) precursors linked to glutathione (GSH) and cysteine (Cys). The treatment determined a positive extraction trend between the duration (untreated, 3 and 5 min) and the conductivity or the concentration of catechins and total phenols, significantly differentiated after 5 min. Nevertheless, the concentration of the thiol precursors in grape juice not only remained undifferentiated, but that of 3-S-glutathionyl mercaptohexan-1-ol showed a negative trend with the treatment time applied (168 ± 43, 156 ± 36, and 149 ± 32 μg/L, respectively, for control, 3 and 5 min). The divergence on the effect between families of compounds suggests an interaction between the sonication treatment and thiol precursor molecules. In order to evaluate the possible degradation properly, ultrasound was applied in a model solution spiked with 3MH and 4MMP precursors, reproducing the conditions of grapes. Except for Cys-3MH, the mean concentration (n = 5) for the rest of the precursors was significantly lower in treated samples, predominantly in those linked to glutathione (~−22% and ~18% for GSH-3MH and GSH-4MMP) rather than to cysteine (~−6%~−8% for Cys-3MH and Cys-4MMP). The degradation of precursors was associated with a significant increase of 3MH and 4MMP. The formation of volatile thiols following sonication is interesting from a technological point of view, as they are key aroma compounds of wine and potentially exploitable in the wine industry through specific vinification protocols.

A glutathione transferase (GST) mutant with four active-site substitutions (Phe10 → Pro/Ala12 → Trp/Leu107 → Phe/Leu108 → Arg) (C36) was isolated from a library of active-site mutants of human GST A1-1 by the combination of phage display and mechanism-based affinity adsorption [Hansson, Widersten and Mannervik (1997) Biochemistry 36, 11252-11260]. C36 was selected on the basis of its affinity for the transition-state analogue 1-(S-glutathionyl)-2,4,6-trinitrocyclohexadienate. C36 affords a 105-fold rate enhancement over the uncatalysed reaction between reduced glutathione and 1-chloro-2,4-dinitrobenzene (CDNB), as evidenced by the ratio between kcat/Km and the second-order rate constant k2. The present study shows that C36 can evolve to an even higher catalytic efficiency by an additional site-specific mutation. Random mutations of the fifth active-site residue 208 allowed the identification of 18 variants, of which the mutant C36 Met208 → Cys proved to be the most active form. The altered activity was substrate selective such that the catalytic efficiency with CDNB and with 1-chloro-6-trifluoromethyl-2,4-dinitrobenzene were increased 2-3-fold, whereas the activity with ethacrynic acid was decreased by a factor of 8. The results show that a single-point mutation in the active site of an enzyme may modulate the catalytic activity without being directly involved as a functional group in the enzymic mechanism. Such limited modifications are relevant both to the natural evolution and the in vitro redesign of proteins for novel functions.

Blast overpressure (BOP) is a phenomenon that describes the instantaneous rise in atmospheric pressure above ambient, resulting from the firing of large caliber weapons or from military or civilian explosions. Exposure to BOP results in injury to the gas-filled organs, such as the lungs, which exhibit a contusion-type injury. We examined the effects of BOP in rats at 5 and 60 min after exposure to a low-level BOP (62 +/- 3 kPa). The exposure was found to cause oxidative stress in the lung that was characterized by 1) a 3.5-fold decrease in total antioxidant reserves, 2) a depletion of the major water-soluble antioxidants ascorbate and glutathione (GSH) by 50 and 75%, respectively, 3) a depletion of lipid-soluble antioxidant vitamin E by 30%, 4) a 2.5-fold increase of fluorescent end products of lipid peroxidation, and 5) an increased methemoglobin (metHb) content at 60 min after exposure. To elucidate the role of released hemoglobin (Hb) in blast-induced oxidative stress, we studied the interactions of oxyhemoglobin (oxyHb), metHb, and the oxoferryl from of Hb free radical species with two physiologically important reductants, ascorbate and GSH. We found that both ascorbate and GSH were able to convert oxyHb to metHb in a reaction that yielded the one-electron oxidation intermediates semidehydroascorbyl radical and glutathionyl radical, respectively. This reaction did not occur under anaerobic conditions, suggesting that oxyHb-bound O2 acted as the electron acceptor. OxyHb induced peroxidation of cis-parinaric acid in the presence but not absence of ascorbate or GSH. Thus the prooxidant action of water-soluble antioxidants via redox cycling of oxyHb and metHb may promote oxidative stress rather than prevent it.

Introduction: Natural curcuminoids isolated from turmeric (Curcuma longa L.) have been limited in number and the amount of substrates evaluated in semi-synthetic processes and biological tests. Currently, potent anticancer activities of curcuminoids have garnered increased attention such that a greater number of synthetic procedures of curcumin analogues have been developed for further biological evaluations. The fluorine substituent of fluorinated compounds is important for biological responses. However, natural products bearing fluorine have rarely been found. In the study herein, we employed an aldol condensation between 4-hydroxy-3-methoxybenzaldehyde/3,4- difluorobenzaldehyde and pentane-2,4-dione to synthesize the desired curcumin (Cur) and 3,4- difluorinated curcumin (3,4-DFCur). Their half-maximal inhibitory concentration (IC50) values against HepG2, LU-1 and KB cancer cell lines were then assessed. Methods: Pentane-2,4-dione was converted to enol form by using B2O3 before carrying out C-C coupling reactions with benzaldehyde analogues under basic conditions. The water scavenger was added to the reaction to capture the produced water. The reaction mixture was stirred at 70 ◦C. The reaction progress was monitored by thin layer chromatography (TLC). Crude products were purified by flash column chromatography (CC; SiO2, eluent: HEX/EA = 9/1!7/3). The chemical structures of the desired products were elucidated by 1H, 13C-NMR, HSQC and MS spectra. The anticancer activities of Cur and 3,4- DFCur against HepG2, LU-1 and KB cancer cell lines were determined using MTT method. Results: Under reasonable reaction conditions, the yields for the coupling reactions were 53 and 72% for Cur and 3,4-DFCur, respectively. The stable enol tautomer of 1,3-diketone and the trans-configuration in a seven-carbon chain of product skeletons were assigned by 1H-NMR spectra. All synthesized products showed anticancer activities, with Cur exhibiting higher inhibitory activities when compared with 3,4-DFCur. Cur and 3,4-DFCur are Michael Acceptors; their cytotoxic activities could be attributed to the inhibition of glutathione S-transferase, a detoxification enzyme, by forming glutathionyl adducts. The decreased inhibitory capacities of 3,4-DFCur were due to the effect of fluorine which results in the unfavorable formation of reactive radicals and an increase in lipophilicity. Conclusions: Curcumin and 3,4-difluorinated curcumin were completely synthesized in 53% and 72% yields. The synthetic procedure is applicable for synthesizing curcumin derivatives bearing various substituents on the aromatic rings, i.e., not limited to methoxy (-OCH3) and hydroxy (- OH) groups. Unexpectedly, the presence of fluorines in 3,4-DFCur led to lower cytotoxic activities against cancer cell lines. Our results provide greater insight on the structure-activity relationship of curcumin analogues against cancer cell lines.

Our studies have indicated that the relative concentration of Se or Hg to As in urine and blood positively correlates with percentage of inorganic arsenic (% Inorg-As) and percentage of monomethlyarsonic acid [% MMA (V)]. We also found a negative correlation with percentage of dimethylarsinic acid [% DMA (V)] and the ratio of % DMA (V) to % MMA (V). In another study, we found that a group of proteins were significantly over expressed and conversely other groups were under-expressed in tissues in Na-As (III) treated hamsters. Introduction.Inorganic arsenic (Inorg-As) in drinking water.One of the largest public health problems at present is the drinking of water containing levels of Inorg-As that are known to be carcinogenic. At least 200 million people globally are at risk of dying because of arsenic (As) in their drinking water1-3. The chronic ingestion of Inorg-As can results in skin cancer, bladder cancer, lung cancer, and cancer of other organs1-3. The maximum contamination level (MCL) of U.S. drinking water for arsenic is 10 ug/L. The arsenic related public health problem in the U.S. is not at present anywhere near that of India4, Bangladesh4, and other countries5. Metabolism and toxicity of Inorg-As and arsenic species.Inorg-As is metabolized in the body by alternating reduction of pentavalent arsenic to trivalent form by enzymes and addition of a methyl group from S-adenosylmethionine6, 7; it is excreted mainly in urine as DMA (V)8. Inorganic arsenate [Inorg-As (V)]is biotransformed to Inorg-As (III), MMA (V), MMA (III), DMA (V), and DMA (III)6(Fig. 1). Therefore, the study of the toxicology of Inorg-As (V) involves at least these six chemical forms of arsenic. Studies reported the presence of 3+ oxidation state arsenic biotransformants [MMA (III) and DMA (III)] in human urine9and in animal tissues10. The MMA (III) and DMA (III) are more toxic than other arsenicals11, 12. In particular MMA (III) is highly toxic11, 12. In increased % MMA in urine has been recognized in arsenic toxicity13. In addition, people with a small % MMA in urine show less retention of arsenic14. Thus, the higher prevalence of toxic effects with increased % MMA in urine could be attributed to the presence of toxic MMA (III) in the tissue. Previous studies also indicated that males are more susceptible to the As related skin effects than females13, 15. A study in the U.S population reported that females excreted a lower % Inorg-As as well as % MMA, and a higher % DMA than did males16. Abbreviation: SAM, S-adenosyl-L-methionine; SAHC, S-adenosyl-L-homocysteine. Differences in susceptibility to arsenic toxicity might be manifested by differences in arsenic metabolism among people. Several factors (for examples, genetic factors, sex, duration and dosage of exposure, nutritional and dietary factors, etc.) could be influence for biotransformation of Inorg-As,6, 17 and other unknown factors may also be involved. The interaction between As, Se, and Hg.The toxicity of one metal or metalloid can be dramatically modulated by the interaction with other toxic and essential elements18. Arsenic and Hg are toxic elements, and Se is required to maintain good health19. But Se is also toxic at high levels20. Recent reports point out the increased risk of squamous cell carcinoma and non-melanoma skin cancer in those treated with 200 ug/day of selenium (Nutritional Prevention of Cancer Trial in the United States)21. However, it is well known that As and Se as well as Se and Hg act as antagonists22. It was also reported that Inorg-As (III) influenced the interaction between selenite and methyl mercury23. A possible molecular link between As, Se, and Hg has been proposed by Korbas et al. (2008)24. The identifying complexes between the interaction of As and Se, Se and Hg as well as As, Se, and Hg in blood of rabbit are shown in Table 1. Influence of Se and Hg on the metabolism of Inorg-As.The studies have reported that Se supplementation decreased the As-induced toxicity25, 26. The concentrations of urinary Se expressed as ug/L were negatively correlated with urinary % Inorg-As and positively correlated with % DMA27. The study did not address the urinary creatinine adjustment27. Other researchers suggested that Se and Hg decreased As methylation28-31(Table 2). They also suggested that the synthesis of DMA from MMA might be more susceptible to inhibition by Se (IV)29 as well as by Hg (II)30,31 compared to the production of MMA from Inorg-As (III). The inhibitory effects of Se and Hg were concentration dependent28-31. The literature suggests that reduced methylation capacity with increased % MMA (V), decreased % DMA (V), or decreased ratios of % DMA to % MMA in urine is positively associated with various lesions32. Lesions include skin cancer and bladder cancer32. The results were obtained from inorganic arsenic exposed subjects32. Our concern involves the combination of low arsenic (As) and high selenium (Se) ingestion. This can inhibit methylation of arsenic to take it to a toxic level in the tissue. Dietary sources of Se and Hg.Global selenium (Se) source are vegetables in the diet. In the United States, meat and bread are the common source. Selenium deficiency in the US is rare. The US Food and Drug Administration (FDA) has found toxic levels of Se in dietary supplements, up to 200 times greater than the amount stated on the label33. The samples contained up to 40,800 ug Se per recommended serving. For the general population, the most important pathway of exposure to mercury (Hg) is ingestion of methyl mercury in foods. Fish (including tuna, a food commonly eaten by children), other seafood, and marine mammals contain the highest concentrations. The FDA has set a maximum permissible level of 1 ppm of methyl mercury in the seafood34. The people also exposed mercury via amalgams35. Proteomic study of Inorg-As (III) injury.Proteomics is a powerful tool developed to enhance the study of complex biological system36. This technique has been extensively employed to investigate the proteome response of cells to drugs and other diseases37, 38. A proteome analysis of the Na-As (III) response in cultured lung cells found in vitro oxidative stress-induced apoptosis39. However, to our knowledge, no in vivo proteomic study of Inorg-As (III) has yet been conducted to improve our understanding of the cellular proteome response to Inorg-As (III) except our preliminary study 40. Preliminary Studies: Results and DiscussionThe existing data (Fig. 1) from our laboratory and others show the complex nature of Inorg-As metabolism. For many years, the major way to study, arsenic (As) metabolism was to measure InorgAs (V), Inorg-As (III), MMA (V), and DMA (V) in urine of people chronically exposed to As in their drinking water. Our investigations demonstrated for the first time that MMA (III) and DMA (III) are found in human urine9. Also we have identified MMA (III) and DMA (III) in the tissues of mice and hamsters exposed to sodium arsenate [Na-As (V)]10, 41. Influence of Se as well as Hg on the As methyltransferase.We have reported that Se (IV) as well as mercuric chloride (HgCl2) inhibited As (III) methyltransferase and MMA (III) methyltransferase in rabbit liver cytosol. Mercuric chloride was found to be a more potent inhibitor of MMA (III) methyltransferase than As (III) methyltransferase30. These results suggested that Se and Hg decreased arsenic methylation. The inhibitory effects of Se and Hg were concentration dependent30. Influence of Se and Hg in urine and blood on the percentage of urinary As metabolites.Our human studies indicated that the ratios of the concentrations of Se or Hg to As in urine and blood were positively correlated with % Inorg-As and % MMA (V). But it negatively correlated with % DMA (V) and the ratios of % DMA (V) to % MMA (V) in urine of both males and females (unpublished data) (Table 3). These results confirmed that the inhibitory effects of Se as well as Hg for the methylation of Inorg-As in humans were concentration dependent. We also found that the concentrations of Se and Hg were negatively correlated with % Inorg-As and % MMA (V). Conversely it correlated positively with % DMA (V) and the ratios of % DMA (V) to % MMA (V) in urine of both sexes (unpublished data). These correlations were not statistically significant when urinary concentrations of Se and Hg were adjusted for urinary creatinine (Table 3). Interactions of As, Se, Hg and its relationship with methylation of arsenic are summarized in Figure 2. Sex difference distribution of arsenic species in urine.Our results indicate that females have more methylation capacity of arsenic as compared to males. In our human studies (n= 191) in Mexico, we found that females (n= 98) had lower % MMA (p<0.001) and higher % DMA (p=0.006) when compared to males (n= 93) (Fig. 3). The means ratio of % MMA (V) to % Inorg-As and % DMA (V) to %MMA (V) were also lower (p<0.05) and higher (p<0.001), respectively in females compared to males. The protein expression profiles in the tissues of hamsters exposed to Na-As (III).In our preliminary studies40, hamsters were exposed to Na-As (III) (173 pg/ml as As) in their drinking water for 6 days and control hamsters were given only the water used to make the solutions for the experimental animals. After DIGE (Two-dimensional differential in gel electrophoresis) and analysis by the DeCyder software, several protein spots were found to be over-expressed (red spot) and several were under expressed (green spot) as compared to control (Figs. 4a-c). Three proteins (one was over-expressed and two were under-expressed) of each tissue (liver and urinary bladder) were identified by LC-MS/MS (liquid chromatography-tandem mass spectrometry).DIGE in combination with LC-MS/MS is a powerful tool that may help cancer investigators to understand the molecular mechanisms of cancer progression due to Inorg-As. Propose a new researchThese results suggested that selenium (Se) as well as mercury (Hg) may influence the methylation of Inorg-As and this influence could be dependent on the concentration of Se, Hg and/or the sex of the animal. Our study also suggested that the identification and functional assignment of the expressed proteins in the tissues of Inorg-As (III) exposed animals will be useful for understanding and helping to formulate a theory dealing with the molecular events of arsenic toxicity and carcinogenicity.Therefore, it would be very useful if we could do a research study with combination of Inorg-arsenic, Se, and Hg. The new research protocol could be the following:For metabolic processing, hamsters provide a good animal model. For carcinogenesis, mouse model is well accepted. The aims of this project are: 1) To map the differential distributions of arsenic (As) metabolites/species in relation to selenium (Se) and mercury (Hg) levels in male and female hamsters and 2) To chart the protein expression profile and identify the defense proteins in mice and hamsters after As injury. Experimental hamsters (male or female) will include four groups. The first group will be treated with Na arseniteNa-As(III), the second group with Na-As (III) and Na-selenite (Na-Se (IV)], the third group with Na As (III) and methyl mercuric chloride (MeHgCl), and the final group with Na-As (III), Na-Se (IV), and MeHgci at different levels. Urine and tissue will be collected at different time periods and measured for As species using high performance liquid chromatography/inductively coupled plasma-mass spectrometry (HPLC/ICP-MS). For proteomics, mice (male and female) and hamsters (male and female) will be exposed to Na-As (III)at different levels in tap water, and control mice and hamsters will be given only the tap water. Tissue will be harvested at different time periods. TWO dimensional differential in gel electrophoresis (2D-DIGE) combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) will be employed to identify the expressed protein. In summary, we intend to extend our findings to: 1) Differential distribution of As metabolites in kidney, liver, lung, and urinary bladder of male and female hamsters exposed to Na-As (III), and combined with Na-As (III) and Na-Se (IV) and/or MeHgCl at different levels and different time periods, 2) Show the correlation of As species distribution in the tissue and urine for both male and female hamsters treated with and without Na-Se (IV) and/or MeHgCl, and 3) Show protein expression profile and identify the defense proteins in the tissues (liver, lung, and urinary bladder epithelium) in mice after arsenic injury. The significance of this study: The results of which have the following significances: (A) Since Inorg-As is a human carcinogen, understanding how its metabolism is influenced by environmental factors may help understand its toxicity and carcinogenicity, (B) The interactions between arsenic (As), selenium (Se), and mercury (Hg) are of practical significance because populations in various parts of the world are simultaneously exposed to Inorg-As & Se and/or MeHg, (C) These interactions may inhibit the biotransformation of Inorg-As (III) which could increase the amount and toxicity of Inorg-As (III) and MMA (III) in the tissues, (D) Determination of arsenic species profile in the tissues after ingestion of Inorg-As (III), Se (IV), and/or MeHg+ will help understand the tissue specific influence of Se and Hg on Inorg-As (III) metabolism, (E) Correlation of arsenic species between tissue and urine might help to understand the tissue burden of arsenic species when researchers just know the distribution of arsenic species in urine, (F) The identification of the defense proteins (over-expressed and under-expressed) in the tissues of the mouse may lead to understanding the mechanisms of inorganic arsenic injury in human. The Superfund Basic Research Program NIEHS Grant Number ES 04940 from the National Institute of Environmental Health Sciences supported this work. Additional support for the mass spectrometry analyses was provided by grants from NIWHS ES 06694, NCI CA 023074 and the BIO5 Institute of the University of Arizona. Acknowledge:The Authorwantsto dedicate this paper to the memory of Dr. H. VaskenAposhian and Dr. Mary M. Aposhian who collected urine and bloodsamples from Mexican population. The work was done under Prof. H. V. Aposhian sole supervision and with his great contribution. References NRC (National Research Council). Arsenic in Drinking Water. Update to the 1999 Arsenic in Drinking Water Report. National Academy Press, Washington, DC. 2001. Gomez-Caminero, A.; Howe, P.; Hughes, M.; Kenyon, ; Lewis, D. R.; Moore, J.; Mg, J.; Aitio, A.; Becking, G. Environmental Health Criteria 224. Arsenic and Arsenic Compounds (Second Edition). 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The main effect of lipid peroxidation, which often occurs in response to oxidative stress, is the production of different toxic aldehydes. In particular, over the years, the lipid peroxidation-derived aldehyde 4-hydroxy-trans-2-nonenal (HNE) has received much attention for its dual role in the pathogenesis of several diseases and as signaling molecule. HNE metabolism is reported to mainly occur through its conjugation with glutathione (GSH) and the subsequent formation of 3-glutathionyl-4-hydroxynonanal (GSHNE) [1, 2]. This molecule is susceptible to both oxidative and reductive transformations, which occur through the action of either the NADPH-dependent activity of aldose reductase (AKR1B1) [1] or through the NAD(P)+ -dependent activity of aldehyde dehydrogenase, respectively [3, 4]. Recently, we have demonstrated the implication of a new NADP+-dependent enzymatic activity able to oxidize GSHNE to its corresponding acid 3-glutathionyl-nonanoic-γ-lactone (GSHNA-γ-lactone) [5]. The enzyme was purified from a human astrocytoma cells line (ADF) to electrophoretic homogeneity as protein doublet in SDS-PAGE, with an apparent molecular weight of 31-32 kDa. Proteomic analysis identified both proteins as human CBR1, also known as NADP+ 15-hydroxyprostaglandine dehydrogenase with 74% of homology and proved their migration differences due to the occurrence of a carboxyethyl moiety at Lys239 [5]. This modification has been already described for the human enzyme and has been demonstrated to have no effect on the protein activity and specificity [6, 7]. The enzyme efficiently catalyzes the oxidation of GSHNE, while it is practically inactive towards 4-hydroxy trans-2-nonenal and other HNE-S-thiolated adducts containing an incomplete glutathionyl moiety [5]. Nucleotide sequence analysis of hCBR1 cDNA from ADF cells completely matched with the human wild type counterpart [5], excluding any gain-of-function mutations in the cDNA-derived protein sequence of hCBR1 [8, 9]. Highly purified human recombinant carbonyl reductase 1 (E.C. 1.1.1.184, hCBR1), which preserves its ability to oxidize specifically GSHNE, is also shown to efficiently act as aldehyde reductase on glutathionylated alkanals, namely 3-glutathionyl-4-hydroxynonanal (GSHNE), 3-glutathionyl-nonanal, 3-glutathionyl-hexanal and 3-glutathionyl-propanal [10]. The presence of the glutathionyl moiety appears as a necessary requirement for the susceptibility of these compounds to the NADPH-dependent reduction by hCBR1. In fact the corresponding alkanals and alkenals, and the cysteinyl and γ-glutamyl-cysteinyl alkanals adducts were either ineffective or very poorly active as CBR1 substrates [10]. Mass spectrometry analysis reveals the ability of hCBR1 to reduce GSHNE to the corresponding 3-glutathionyl-1,4-dihydroxynonane (GSDHN) and at the same time to catalyze the oxidation of the hemiacetal form of GSHNE, generating the 3-glutathionylnonanoic-γ-lactone. These data are indicative of the ability of the enzyme to catalyze a disproportion reaction of the substrate through the redox recycle of the pyridine cofactor [10]. A rationale for the observed preferential activity of hCBR1 on different GSHNE diastereoisomers is given by molecular modelling. These results evidence the potential of hCBR1 acting on GSHNE to accomplish a dual role, both in terms of HNE detoxification and, through the production of GSDHN, in terms of involvement into the signalling cascade of the cellular inflammatory response.