Purification and Properties of a Malolactic Enzyme from a Strain of Leuconostoc mesenteroides Isolated from Grapes.

An enzymatic complex able to transform l-malate to l-lactate was obtained from a Leuconostoc mesenteroides strain isolated from grapes. The molecular weight was about 235,000, the isoelectric point was at pH 4.35, and the optimal pH for activity was 5.75. The malolactic activity followed a sequential pattern concerning the involved substrates. At pH values substantially different from the optimum, a positive cooperativity between malate molecules was observed. Oxamate, fructose-1, 6-diphosphate, and l-lactate acted as noncompetitive inhibitors, whereas succinate, citrate, and tartrate isomers produced a competitive inhibition.