H. Ono et al., PURIFICATION AND CHARACTERIZATION OF A CELL-WALL ASSOCIATED PROTEINASE OF LACTOBACILLUS-HELVETICUS CP53, Milchwissenschaft, 52(7), 1997, pp. 373-377
An extracellular proteinase was purified from Lactobacillus helveticus
CP53 cells to homogeneity by DEAE ion exchange chromatography followe
d by casein-sepharose. The molecular mass of this enzyme was estimated
to be 170,000 by SDS-7%PAGE. The enzyme had a maximum activity at pH
6.5 and 42 degrees C, and the activity was completely inhibited by the
addition of phenyl methane sulfonyl fluoride. (PMSF). From the compar
ative study of the proteinase in the specificity towards beta-casein,
some differences were observed in the hydrolyzation pattern between L.
helveticus CP53 and other strains. Significant difference was observe
d in the specificity of the enzymes towards a beta-casein peptide, Ser
-Trp-Met-His-Gln-Pro-His. The degradation product of a synthetic pepti
de of alpha(s1)-casein fragment (1 to 23) by the proteinase of CP53 wa
s also different from that of other strains. These results suggested t
hat the proteinase of L. helveticus CP53 is a different type of enzyme
from those identified so far among the L. helveticus proteinases.