Detection of Cell-Associated Aminoterminal Procollagen Peptidase Activity in Cultured Fibroblasts

Abstract

Abstract

Aminoterminal procollagen peptidase activity was assayed in cultures of human fibroblasts derived from fetal, neonatal, and adult skin. Tritium-labeled, acid-extracted pN collagen from chick calvarial bones was used as substrate. Peptidase activity was detected in both the culture medium and the cell homogenate of fetal and neonatal fibroblast strains. The cell layer and medium peptidase enzymes were inhibited by 20 mM EDTA and acidic pH. In contrast, procollagen peptidase activity was detected only in the culture medium of adult fibroblasts as previously reported (8). These results suggest that the aminoterminal procollagen peptidase enzyme in fetal and neonatal fibroblasts is either activated prior to secretion from the cell, or that the activated enzyme is bound to the cell surface for a limited time before its release into the culture medium.