Modification of an arginine residue in pig kidney general acyl-coenzyme A dehydrogenase by cyclohexane-1,2-dione.
The flavoenzyme pig kidney general acyl-CoA dehydrogenase (EC 1.3.99.3) is inactivated by cyclohexane-1,2-dione in borate buffer in a reaction that exhibits pseudo-first-order kinetics. Strong protection is afforded by the substrate octanoyl-CoA, as well as by heptadecyl-CoA, a potent competitive inhibitor of the dehydrogenase that does not reduce enzyme flavin. Enzyme exhibiting 10% residual activity in borate buffer contains about 1.3 modified arginine residues per flavin molecule. Very little reduction of the modified enzyme in borate buffer occurs at high concentrations of octanoyl-CoA, in marked contrast with the stoicheiometric reduction of the native enzyme. However, in phosphate buffer alone, the modified enzyme exhibits 55% residual activity and, although binding of substrate is still seriously impaired (apparent Kd=14 microM), excess substrate effects the formation of the characteristic reduced flavin X enoyl-CoA charge-transfer complex. These results suggest that the susceptible arginine residue, though not catalytically essential, is probably within the acyl-CoA-binding site of general acyl-CoA dehydrogenase.
D000214:Acyl Coenzyme A / Q000378:metabolism; D042964:Acyl-CoA Dehydrogenase; D044944:Acyl-CoA Dehydrogenases / Q000037:antagonists & inhibitors*; D000818:Animals; D001120:Arginine / Q000378:metabolism*; D001665:Binding Sites; D003510:Cyclohexanes / Q000494:pharmacology*; D003512:Cyclohexanones / Q000494:pharmacology*; D003931:Diacetyl / Q000494:pharmacology; D005227:Fatty Acids / Q000378:metabolism*; D007668:Kidney / Q000201:enzymology*; D010658:Phenylglyoxal / Q000494:pharmacology; D013552:Swine
D000214:Acyl Coenzyme A; D003510:Cyclohexanes; D003512:Cyclohexanones; D005227:Fatty Acids; C034681:octanoyl-coenzyme A; C032420:heptadecanoyl-coenzyme A; C018031:1,2-cyclohexanedione; D001120:Arginine; D044944:Acyl-CoA Dehydrogenases; D042964:Acyl-CoA Dehydrogenase; D003931:Diacetyl; D010658:Phenylglyoxal