Thiamine pyrophosphate as an effector of 2-oxoglutarate dehydrogenase complex from European bison heart.
The purified 2-oxoglutarate dehydrogenase complex (OGDC) from the European bison heart was near saturated with endogenous bound thiamine pyrophosphate (TPP). Exogenous TPP added to the full OGDC reaction medium decreased S0.5 for 2-oxoglutarate approximately 2.6-fold without any notable change in the maximum reaction rate. The TPP effect was observed in the presence of 1 mM ADP which alone is a strong positive allosteric effector of OGDC. At an unsaturating 2-oxoglutarate concentration the A50 value for TPP was approximately 0.05 mM. The ADP-like action of exogenous TPP was also found in the 2-oxoglutarate dehydrogenase (E1) reaction, determined in the presence of 2,6-dichlorophenoloindophenol as an electron acceptor.
Strumilo
S
S
Department of Biochemistry, University of Warsaw, Bialystok, Poland.
Markiewicz
J
J
D000244:Adenosine Diphosphate / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D016164:Bison; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D007655:Ketoglutarate Dehydrogenase Complex / Q000187:drug effects* / Q000378:metabolism*; D007700:Kinetics; D009206:Myocardium / Q000201:enzymology*; D013835:Thiamine Pyrophosphate / Q000378:metabolism* / Q000494:pharmacology*
D000244:Adenosine Diphosphate; D007655:Ketoglutarate Dehydrogenase Complex; D013835:Thiamine Pyrophosphate; D002118:Calcium