title: [Formation of oligomeric form of transketolase and the factors influencing this process].
abstract: The immobilized transketolase (dimer) is a mixture of two enzyme forms, i. e. a completely active and completely inactive ones. The decomposition of the active enzyme form into subunits to form immobilized monomers occurs at a higher rate than that of the inactive form. The reassociation of the monomers with a formation of dimers strongly depends on pH, the pH optimum of reassociation being equal to 7,9--9,2. Thiamine pyrophosphate and Ca2+ as well as Ca2+ alone but taken at sufficiently high concentrations favours the association of the monomers into a dimer. The reassociated dimers exhibit a complete catalytic activity only when the reassociation occurs in the presence of Ca2+. The activity of reassociated dimers obtained in the absence of Ca2+ was decreased by 50%. The reassociation capacity of the immobilized subunits obtained in the absence of beta-mercaptoethanol was considerably decreased. The immobilized subunits obtained in the presence of beta-mercaptoethanol and then treated by N-ethylmaleimide were not capable of reassociation.
mesh_terms: D002118:Calcium / Q000494:pharmacology; D004800:Enzymes, Immobilized / Q000378:metabolism; D005033:Ethylmaleimide / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D046911:Macromolecular Substances; D008623:Mercaptoethanol / Q000494:pharmacology; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D013835:Thiamine Pyrophosphate / Q000494:pharmacology; D014174:Transketolase / Q000378:metabolism
chemical_list: D004800:Enzymes, Immobilized; D046911:Macromolecular Substances; D008623:Mercaptoethanol; D014174:Transketolase; D005033:Ethylmaleimide; D013835:Thiamine Pyrophosphate; D002118:Calcium
vernacular_title: Obrazovanie oligomernoĭ formy transketolazy i faktory, vliiaiushchie na etot protsess.