title: Medium-chain acyl coenzyme A dehydrogenase from pig kidney has intrinsic enoyl coenzyme A hydratase activity.
abstract: The flavoprotein medium-chain acyl coenzyme A (acyl-CoA) dehydrogenase from pig kidney exhibits an intrinsic hydratase activity toward crotonyl-CoA yielding L-3-hydroxybutyryl-CoA. The maximal turnover number of about 0.5 min-1 is 500-1000-fold slower than the dehydrogenation of butyryl-CoA using electron-transferring flavoprotein as terminal acceptor. trans-2-Octenoyl- and trans-2-hexadecenoyl-CoA are not hydrated significantly. Hydration is not due to contamination with the short-chain enoyl-CoA hydratase crotonase. Several lines of evidence suggest that hydration and dehydrogenation reactions probably utilize the same active site. These two activities are coordinately inhibited by 2-octynoyl-CoA and (methylenecyclopropyl)acetyl-CoA [whose targets are the protein and flavin adenine dinucleotide (FAD) moieties of the dehydrogenase, respectively]. The hydration of crotonyl-CoA is severely inhibited by octanoyl-CoA, a good substrate of the dehydrogenase. The apoenzyme is inactive as a hydratase but recovers activity on the addition of FAD. Compared with the hydratase activity of the native enzyme, the 8-fluoro-FAD enzyme exhibits a roughly 2-fold increased activity, whereas the 5-deaza-FAD dehydrogenase is only 20% as active. A mechanism for this unanticipated secondary activity of the acyl-CoA dehydrogenase is suggested.
mesh_terms: D044944:Acyl-CoA Dehydrogenases / Q000302:isolation & purification / Q000378:metabolism*; D000818:Animals; D004746:Enoyl-CoA Hydratase / Q000302:isolation & purification / Q000378:metabolism*; D005182:Flavin-Adenine Dinucleotide / Q000031:analogs & derivatives; D006836:Hydro-Lyases / Q000378:metabolism*; D007668:Kidney / Q000201:enzymology*; D007700:Kinetics; D013379:Substrate Specificity; D013552:Swine
chemical_list: D005182:Flavin-Adenine Dinucleotide; D044944:Acyl-CoA Dehydrogenases; D006836:Hydro-Lyases; D004746:Enoyl-CoA Hydratase