Abstract
Acid and neutral proteinases are distributed in the cervical stroma of the human uterus, and the former activity is about 10 times that of the latter. The acid proteinase was completely separated from the neutral enzyme by Sephadex G-200 gel filtration and the acid enzyme was purified about 630-fold to homogenity by ion-exchange chromato-graphy on DEAE-Sephadex A-50 and rechromatography on Sephadex G-200. The purified acid proteinase showed the optimum pH in the range from 3.4 to 3.6 for acid-and ureadenatured bovine hemoglobins, and was completely inhibited by pepstatin and N-bromosuccinimide. Its molecular weight was calculated to be 4.2×104 by gel filtration on Sephadex G-75. From these results, this enzyme could be identified as cathepsin D.
