An alkaline metallo-proteinase in the human uterine cervix and 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 · 10⁴) was most active around pH 9.2 toward casein and $\text{Nα-}\text{benzoyl-}\text{dl}\text{-Arg}\text{-p-}\text{nitroanilide}$. [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.