Indolelactate dehydrogenase from Clostridium sporogenes

Indolelactate dehydrogenase has been purified 13-fold from cell-free extracts of Clostridium sporogenes. The enzyme is inactive with lactate, but active with indolelactate, phenyllactate, and p-hydroxyphenyllactate, and utilizes nicotinamide adenine dinucleotide (NAD) but not nicotinamide adenine dinucleotide phosphate NADP (1), as coenzyme. The reaction is reversible; the equilibrium constant is 6.3 × 10 − 6 M at pH 7.0, expressed as [indolepyruvate] [NADH] [H + ]/[indolelactate] [NAD].The enzyme preparation exhibits regular Michaelis–Menten kinetics with respect to indolelactate, NAD, and NADP, but not with respect to indolepyruvate.