PURIFICATION AND CHARACTERIZATION OF A CYSTEINE PROTEINASE FROM LACTOCOCCUS-LACTIS SSP. LACTIS IAM-1198

A proteinase from Lactococcus lactis ssp. lactis IAM 1198 was purified to homogeneity by conventional chromatographic techniques. The molecu lar mass of the enzyme was estimated to be 51 kDa by SDS-PAGE. Activit y was maximal at pH 6.4 and 35 degrees C. The enzyme was stable at pH values from 6.0 to 8.0 and below 40 degrees C. The enzyme seemed to be a cysteine proteinase because it was inhibited by p-chloromercuriphen yl sulfonic acid. The Michaelis constant of the enzyme for L-phenylala nyl-L-arginine-7-amido-4-methylcoumarin and L-arginine-7-amido-4-methy lcoumarin was 6.9 M and 16.6M, respectively. The enzyme showed both en dopeptidase and aminopeptidase activity. (C) 1997 Elsevier Science Ltd . All rights reserved.