| Stimulation of the dithiol-dependent reductases in the vitamin K cycle by the thioredoxin system. Strong synergistic effects with protein disulphide-isomerase. | |
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MedLine Citation:
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PMID: 1731762 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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It has been shown previously that the thioredoxin system (thioredoxin + thioredoxin reductase + NADPH) may replace dithiothreitol (DTT) as a cofactor for vitamin KO and K reductase in salt-washed detergent-solubilized bovine liver microsomes. Here we demonstrate that the system can be improved further by adding protein disulphide-isomerase (PDI) to the components mentioned above. Moreover, NADPH may be replaced by reduced RNAase as a hydrogen donor. In our in vitro system the various protein cofactors were required at concentrations 2-5 orders of magnitude lower than that of DDT, whereas the maximal reaction rate was about 3-fold higher. PDI stimulated the thioredoxin-driven reaction about 10-fold, with an apparent Km value of 8 microM. These data suggest that in the vitro system the formation of disulphide bonds is somehow linked to the vitamin K-dependent carboxylation of glutamate residues. In vivo, both disulphide formation and vitamin K-dependent carboxylation are post-translational modifications taking place at the luminal side of the endoplasmic reticulum of mammalian secretory cells. The possibility that the reactions are also coupled in vivo is discussed. |
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Authors:
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B A Soute; M M Groenen-van Dooren; A Holmgren; J Lundström; C Vermeer |
Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: The Biochemical journal Volume: 281 ( Pt 1) ISSN: 0264-6021 ISO Abbreviation: Biochem. J. Publication Date: 1992 Jan |
Date Detail:
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Created Date: 1992-02-18 Completed Date: 1992-02-18 Revised Date: 2009-11-18 |
Medline Journal Info:
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Nlm Unique ID: 2984726R Medline TA: Biochem J Country: ENGLAND |
Other Details:
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Languages: eng Pagination: 255-9 Citation Subset: IM |
Affiliation:
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Department of Biochemistry, University of Limburg, Maastricht, The Netherlands. |
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Carbon-Carbon Ligases* Cattle Coenzymes / metabolism Disulfides / metabolism Dithiothreitol / pharmacology* Escherichia coli / metabolism Glutaredoxins Glutathione Reductase / metabolism* Insulin / metabolism Isomerases / metabolism* Kinetics Ligases / metabolism* Models, Biological NADP / metabolism Oxidoreductases* Protein Disulfide-Isomerases Proteins / metabolism* Ribonucleases / metabolism Swine Thioredoxins / metabolism* Vitamin K / metabolism* |
| Chemical | |
Reg. No./Substance:
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0/Coenzymes; 0/Disulfides; 0/Glutaredoxins; 0/Proteins; 11061-68-0/Insulin; 12001-79-5/Vitamin K; 3483-12-3/Dithiothreitol; 52500-60-4/Thioredoxins; 53-59-8/NADP; EC 1.-/Oxidoreductases; EC 1.8.1.7/Glutathione Reductase; EC 3.1.-/Ribonucleases; EC 5.-/Isomerases; EC 5.3.4.1/Protein Disulfide-Isomerases; EC 6.-/Ligases; EC 6.4.-/Carbon-Carbon Ligases; EC 6.4.-/glutamyl carboxylase |
| Comments/Corrections | |
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