Document Detail

Stimulation of the dithiol-dependent reductases in the vitamin K cycle by the thioredoxin system. Strong synergistic effects with protein disulphide-isomerase.
MedLine Citation:
PMID:  1731762     Owner:  NLM     Status:  MEDLINE    
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.
B A Soute; M M Groenen-van Dooren; A Holmgren; J Lundström; C Vermeer
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Biochemical journal     Volume:  281 ( Pt 1)     ISSN:  0264-6021     ISO Abbreviation:  Biochem. J.     Publication Date:  1992 Jan 
Date Detail:
Created Date:  1992-02-18     Completed Date:  1992-02-18     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  2984726R     Medline TA:  Biochem J     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  255-9     Citation Subset:  IM    
Department of Biochemistry, University of Limburg, Maastricht, The Netherlands.
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Carbon-Carbon Ligases*
Coenzymes / metabolism
Disulfides / metabolism
Dithiothreitol / pharmacology*
Escherichia coli / metabolism
Glutathione Reductase / metabolism*
Insulin / metabolism
Isomerases / metabolism*
Ligases / metabolism*
Models, Biological
NADP / metabolism
Protein Disulfide-Isomerases
Proteins / metabolism*
Ribonucleases / metabolism
Thioredoxins / metabolism*
Vitamin K / metabolism*
Reg. No./Substance:
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 Reductase; EC 3.1.-/Ribonucleases; EC 5.-/Isomerases; EC Disulfide-Isomerases; EC 6.-/Ligases; EC 6.4.-/Carbon-Carbon Ligases; EC 6.4.-/glutamyl carboxylase

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

Previous Document:  Immunosuppressive activity of corticotrophin-releasing factor. Inhibition of interleukin-1 and inter...
Next Document:  Chain-length dependency of interactions of medium-chain fatty acids with glucose metabolism in acini...