73] Acyl dehydrogenases from pig and beef liver and beef heart: RCH2CH2COSCoA − 2H+ − 2e- ⇆ RCHCHCOSCoA

Abstract

Publisher Summary Acyl dehydrogenases of high purity have been prepared from pig, beef, and sheep liver and from beef heart. They are all flavoproteim with FAD as prosthetic group and have all been found to require an additional flavoprotein, the electron-transferring flavoprotein (ETF), for optimal catalytic activity with electron acceptors. Problems posed by this two-enzyme system in the evaluation of kinetic data have been discussed in the chapter. Acyl dehydrogenases from all sources show specificity for the chain length of the fatty acid residue esterified with CoA. The exact specificity pattern is known only for the pig liver enzymes. The chapter describes the assay method, preparation and purification procedure, and properties of acyl dehydrogenases from pig and beef liver and beef heart. The reduction (or oxidation for reverse reaction) of a suitable electron acceptor (donor) is followed spectrophotometrically. 2,6-Dichlorophenolindophenol is the most convenient acceptor for routine assays. However, for this assay ETF is required, and a substrate preparation free of glutathione thioesters. In the assay with phenazine methosulfate ETF is not an absolute requirement, although it accelerates the rate.