| Purification and characterization of 3-mercaptopyruvic acid S-conjugate reductases. | |
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MedLine Citation:
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PMID: 2242034 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Three kinds of 3-mercaptopyruvic acid S-conjugate reductase (MPR-I, MPR-II and MPR-III) were purified from rat liver cytosol. These enzymes reduced 3-mercaptopyruvic acid S-conjugates derived from cysteine conjugates and some endogenous alpha-keto acids to the corresponding alpha-hydroxy acids in the presence of either NADH (for MPR-I and MPR-II) or NADPH (MPR-III), while simple aldehydes or ketones did not significantly induce substrate activity. The molecular weight of the present enzymes was about 80 kDa composed of two subunits of the same molecular weight. Km values of MPR-I, MPR-II and MPR-III were 0.38, 0.06 and 0.29 mM for S-(4-bromophenyl)-3-thiopyruvic acid, respectively, and 0.15 mM for NADH (MPR-I, MPR-II) and NADPH (MPR-III). Vmax values of MPR-I, MPR-II and MPR-III for this substrate were 5.3, 20 and 13 nmol/min/mg, respectively. The sulphydryl-modifying agents inhibited the enzyme activities of all the three reductases. Based on the properties including substrate selectivity for alpha-keto acids derived from aromatic amino acids, we assumed that MPR-II and aromatic alpha-keto acid reductase are the same enzyme, while enzymes similar to MPR-I and MPR-III have not been reported. From the viewpoints of metabolism of xenobiotics, these enzymes are likely to be important in biotransformation of cysteine conjugates to 3-mercaptolactic acid S-conjugates. |
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Authors:
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H Tomisawa; A Okamoto; K Hattori; N Ozawa; F Uda; M Tateishi |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Biochemical pharmacology Volume: 40 ISSN: 0006-2952 ISO Abbreviation: Biochem. Pharmacol. Publication Date: 1990 Nov |
Date Detail:
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Created Date: 1990-12-10 Completed Date: 1990-12-10 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0101032 Medline TA: Biochem Pharmacol Country: ENGLAND |
Other Details:
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Languages: eng Pagination: 2047-57 Citation Subset: IM |
Affiliation:
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Drug Metabolism and Analytical Chemistry Research, Upjohn Pharmaceuticals Limited, Tsukuba Research Laboratories, Ibaraki, Japan. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Chromatography, High Pressure Liquid Cysteine / analogs & derivatives*, metabolism Enzyme Stability Gas Chromatography-Mass Spectrometry Hydrogen-Ion Concentration Liver / enzymology* Male Molecular Weight Oxidoreductases / chemistry, isolation & purification*, metabolism Rats Rats, Inbred Strains Substrate Specificity Tissue Distribution |
| Chemical | |
Reg. No./Substance:
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2464-23-5/3-mercaptopyruvic acid; 52-90-4/Cysteine; EC 1.-/Oxidoreductases |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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