CLEAVAGE OF VICINAL DIOLS BY LIVER MICROSOMES

Publisher Summary This chapter describes a reaction catalyzed by a rat microsomal enzyme that causes the cleavage of a vic-diol to two moles of carbonyl derivative. The reaction requires either nicotinamide adenine dinucleotide phosphate-oxidase (NADPH) or nicotinamide adenine dinucleotide (NADH). An enzyme appears to be present in the microsomal fraction that catalyzes the cleavage of xenobiotic vic-diols. This enzyme has many similarities to P-450 oxygenase but they are unrelated to each other. It is an oxidation enzyme that catalyzes a reverse pinacol synthesis but without an apparent oxidant. It requires a reduced pyridine nucleotide as cofactor. The cleavage of DES-diol by this enzyme is relatively fast. As vic-diols—dihydrodiols—are oxygenation products of unsaturated aliphatics and aromatics by P-450 oxygenase present in the same subcellular fraction, they can also be cleaved by this enzyme to ketones or aldehydes. However, the implications of this possibility cannot be predicted.