[ECP 32 proteinase: characteristics of the enzyme, study of specificity].

Hydrolysis of the C-peptide from recombinant human proinsulin, porcine insulin, and melittin by the E. coli actin-degrading proteinase ECP 32 was studied by reverse phase high performance liquid chromatography and mass spectrometry with electrospray ion source. Proteinase ECP 32 hydrolyzed only melittin at the Ala15-Leu16 or Leu16-Ile17 bonds (KM = 2.4 x 10(-6) M). The effects of pH and buffer composition on the rate of enzymatic hydrolysis were studied. The pH optimum of melittin hydrolysis was 7. Phosphates inhibited, whereas ATP stimulated the hydrolysis of melittin. Melittin was suggested as a substrate for determining the activity of proteinase ECP 32.