PURIFICATION AND PROPERTIES OF THE ALPHA-ACETOLACTATE DECARBOXYLASE FROM LACTOCOCCUS-LACTIS SUBSP LACTIS NCDO-2118

alpha-Acetolactate decarboxylase from Lactococcus lactis subsp. lactis NCDO 2118 was expressed at low levels in cell extracts and was also u nstable. The purification was carried out from E. coli in which the en zyme was expressed 36-fold higher. The specific activity was 24-fold e nhanced after purification. The main characteristics of alpha-acetolac tate decarboxylase were: (i) activation by the three branched chain am ino acids leucine, valine and isoleucine; (ii) allosteric properties d isplayed in absence and Michaelis kinetics in the presence of leucine. The enzyme is composed of six identical subunits of 26,500 Da.