Studies on the reaction mechanism of general acyl-CoA dehydrogenase. Determination of selective isotope effects in the dehydrogenation of butyryl-CoA.
The kinetic properties of general acyl-CoA dehydrogenase from pig kidney have been investigated using normal butyryl-CoA as well as an alpha-deutero, beta-deutero- and perdeutero-butyryl-CoA. In turnover catalysis, isotope effects of 2, 3.6, and 9 were found respectively. In the reductive half reaction the isotope effects were 2.5, 14, and 28 for the same substrates, and 21 for (2R,3R)-(2,3-D2)butyryl-CoA. No intermediates are apparent during the reduction of oxidized enzyme to the presumed complex of reduced enzyme and crotonyl-CoA. The results are interpreted as indicating a high degree of concertedness during the rupture of the alpha and beta C-H bonds. They are compatible with a mechanism in which simultaneously the alpha-hydrogen is abstracted as a proton, while the beta-hydrogen is transferred to the oxidized flavin as a hydride.
D000214:Acyl Coenzyme A / Q000378:metabolism*; D042964:Acyl-CoA Dehydrogenase; D044944:Acyl-CoA Dehydrogenases / Q000378:metabolism*; D002384:Catalysis; D003903:Deuterium; D007553:Isotope Labeling; D007700:Kinetics; D008433:Mathematics; D010084:Oxidation-Reduction
D000214:Acyl Coenzyme A; C024343:butyryl-coenzyme A; D003903:Deuterium; D044944:Acyl-CoA Dehydrogenases; D042964:Acyl-CoA Dehydrogenase