[Pz peptidase activity in serum (author's transl)].

Synthetic PZ peptide, synthesized by Wünsch and Heidrich, was used as substrate to determine PZ peptidase activities in the sera of man, rabbit, guinea pig and mouse. The PZ peptidase from rabbit serum was purified 200 fold and characterized. The enzyme has an isoelectric point of 5.0 and pH optima at pH 7.2 and pH 7.9. Its behaviour on gel filtration points to a molecular weight of 60.000 dalton. The peptidase is inhibited by heavy metal ions, SH reagents and serum. Ca ions are EDTA are without any effect. In contrast to collagen peptidases from micro-organisms, the enzyme from rabbit serum does not attack native, but only denatured collagen. The results suggest that PZ peptidases participate in collagen breakdown by cleaving the collagen fragments which are released by the collagenases.