title: Reduction of protein mixed disulfides (dethiolation) by Escherichia coli thioredoxin: a study with glycogen phosphorylase b and creatine kinase.
abstract: The role of thioredoxin in the reduction of protein mixed disulfides (dethiolation) was studied by electrofocusing methodology with glycogen phosphorylase b and creatine kinase as substrates for the reaction. Glycogen phosphorylase b was effectively dethiolated by Escherichia coli thioredoxin with dithiothreitol as the reductant, while creatine kinase could not be dethiolated by this mechanism. The rate of dethiolation of phosphorylase b was dependent on the concentration of thioredoxin up to a maximum at 20 microM when the concentration of phosphorylase b was 4 microM in monomer. Rat heart contained a thioredoxin reductase activity that could use added E. coli thioredoxin to dethiolate phosphorylase b and the same concentration of thioredoxin as above was required. This activity was not expressed with creatine kinase as the substrate. Cardiac tissue was shown to have a similar endogenous dethiolating activity. These results suggest that thioredoxin may play an important role in dethiolating specific proteins that might become S-thiolated during oxidative stress of cardiac tissue.
authors.affiliation: Department of Biochemistry and Biophysics, Iowa State University, Ames 50011.
authors.forename: E M
authors.initials: EM
authors.lastname: Park
authors.forename: J A
authors.initials: JA
authors.lastname: Thomas
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism*; D002417:Cattle; D003402:Creatine Kinase / Q000378:metabolism*; D004220:Disulfides / Q000378:metabolism*; D004229:Dithiothreitol / Q000378:metabolism; D004926:Escherichia coli / Q000032:analysis*; D007460:Iodoacetamide / Q000494:pharmacology; D007461:Iodoacetates / Q000494:pharmacology; D019807:Iodoacetic Acid; D007525:Isoelectric Focusing; D009132:Muscles / Q000201:enzymology; D009206:Myocardium / Q000201:enzymology; D010084:Oxidation-Reduction; D010763:Phosphorylase b / Q000378:metabolism*; D006005:Phosphorylases / Q000378:metabolism*; D011817:Rabbits; D051381:Rats; D013880:Thioredoxin-Disulfide Reductase / Q000378:metabolism; D013879:Thioredoxins / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D004220:Disulfides; D007461:Iodoacetates; D013879:Thioredoxins; D013880:Thioredoxin-Disulfide Reductase; D010763:Phosphorylase b; D006005:Phosphorylases; D003402:Creatine Kinase; D004229:Dithiothreitol; D019807:Iodoacetic Acid; D007460:Iodoacetamide