Isolation and Characterization of a Prolidase from Streptococcus cremoris H61

Abstract

A prolidase with a molecular weight of 43, 000 was purified to homogeneity from a cell-free extract of Streptococcus cremoris H61. The optimum pH of the enzyme was in the range of 6.5 to 7.5. The hydrolyzing activity was specific for dipeptides of the X-Pro type. Kinetic constants for 4 dipeptides (Leu-Pro, Phe-Pro, Val-Pro and Ala-Pro) were estimated. Km values were not very different for these substrates, but V_max values were quite different (Leu-Pro> Phe-Pro, Val-Pro> Ala-Pro). The enzyme was activated by cobalt ion and inactivated by metal-chelating agents or with 2-mercaptoethanol.