Purification and properties of a malolactic enzyme from Leuconostoc oenos ATCC 23278

The malolactic enzyme of Leuconostoc oenos ATCC 23278 was purified 136fold. The molecular weight was estimated at 132,000 when determined by gel filtration. The enzyme contained two identical subunits (Mw = 66,000 using sodium dodecyl sulfate gel electrophoresis). The malolactic enzyme catalyzes the NAD(+)- and Mn(+)-dependent reaction L-malate----L-lactate + CO2. The apparent Km values for malic acid, NAD+, and Mn2+ were 17 mM, 0.044 mM, and 0.017 mM, respectively. The optimal pH and the optimal temperature for activity were 5.0, and 37 degrees C, respectively and the isoelectric point was pH 4.30. L-lactate and ethanol were non-competitive inhibitors, whereas succinate, citrate, and D-tartrate showed competitive type inhibitions.