An alkaline metallo-proteinase in the human uterine cervix an changes in its activity by cervical ripening.

Human uterine cervix at term pregnancy was found to contain an alkaline metallo-proteinase by use of a synthetic substrate, 2,4-dinitrophenyl-L-Pro-L-Gln-Gly-L-Ile-L-Ala-Gly-L-Gln-D-Arg. The enzyme (with a molecular weight of 3.8 . 10(4)) was most active around pH 9.2 toward casein and N alpha-benzoyl-DL-Arg-rho-nitroanilide. [14C]-Gelatin and proteoglycan subunit were also substrates for the enzyme, but [14C]collagen was not. In particular, the enzyme digested gelatin 70-times faster than the novel neutral proteinase in the cervix. Although EDTA was a potent inhibitor, 1,10-phenanthroline, human serum, diisopropylfluorophosphate and elastatinal had no effect on the enzyme. Alkaline proteinase in term pregnant cervices was significantly higher than in non-pregnant ones.