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

Abstract

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-i,6-diphosphate, and L-lactate acted as noncompetitive inhibitors, whereas succinate, citrate, and tartrate isomers produced a competitive inhibition.

Population dynamics ofOenococcus oenistrains in a new winery and the effect of SO2and yeast strain

“…This confirmed that SO 2 production by yeast strains was negligible. Neither were there any differences in suc-cinate and tartrate contents (0.1-0.15 and 2.0-2.5 g l À1 , respectively), both inhibitors of MLF [25]. The concentrations of acetate at the end of MLF were between 0.1 and 0.2 g l À1 in any case, an acceptable and usual value.…”

Cloning and sequence analysis of the gene encoding Lactococcus lactis malolactic enzyme: Relationships with malic enzymes

“…Protein concentration was determined with the BCA protein assay reagent (Pierce). MLE activity was determined at 37°C by measuring the CO 2 released from L-malate with a specific CO 2 electrode (Eischeweiler and Co) [3]. The specific activity was expressed as micromoles of CO 2 released per minute per milligram of protein.…”

“…The specific activity was expressed as micromoles of CO 2 released per minute per milligram of protein. LDH activity (pyruvate to lactate) was performed as described elsewhere [3]. L-Malate and L-lactate were determined by enzymatic methods (Boehringer Mannheim).…”

“…L. lactis IL1441 malolactic enzyme was purified according to a published procedure [3]. The N-terminal amino acid sequence ( Fig.…”

“…The key enzyme of MLF, malolactic enzyme (MLE), has been purified from many LAB: Lactobacillus plantarum [1], Lactobacillus sp. [2], Leuconostoc mesenteroides [3], Leuconostoc oenos [4,5], Lactobacillus casei [6], and Lactococcus lac-tis (A. Lonvaud, unpublished data). All these enzymes decarboxylate L-malate to L-lactate with the requirement of NAD + and Mn 2+ as cofactors.…”