Purification and Properties of Pyridine Nucleotide-Independent l -Lactate Dehydrogenase from Polyporus circinatus

Abstract

Cell extracts of Polyporus circinatus grown on lactate catalyze the reduction of 2,6-dichlorophenolindophenol by l -lactate without the participation of nicotinamide adenine dinucleotide or nicotinamide adenine dinucleotide phosphate. The enzyme has been purified 78-fold and was homogenous by disc gel electrophoresis. The optimal pH was found to be 6.7. The Michaelis constant for l -lactate was 5.9 × 10 −4 M and the oxalate inhibition constant was 1.5 × 10 −4 M. The nature of the prosthetic group is discussed.