PROLINE-SPECIFIC PEPTIDASES OF LACTOBACILLUS-CASEI SUBSPECIES

This paper describes the specific activities for proline iminopeptidas es, x-prolyl dipeptidyl peptidase and post proline endopeptidase, from each of two subspecies of Lactobacillus casei grown in MRS broth and whey media at 37-degrees-C, pH 6.0. The histochemical PAGE of soluble extracts from one subspecies (Lactobacillus casei ssp. casei LLG) indi cated that the two enzyme activities were due to distinct proteins. Ex cept for a slight increase in x-prolyl dipeptidyl peptidase activity, the activities of proline imino- and endopeptidases of cells grown in whey medium did not vary markedly from those of cells grown in MRS bro th. The effect of inhibitor agents and Ph on the activities of proline iminopeptidase and x-prolyl dipeptidyl peptidase were investigated. T he temperature optima and storage stability under different conditions were also studied for these activities.