Type IV collagen-degrading enzyme activity in human serum.

Type IV collagen-degrading enzyme activity was detected in human serum. Serum was preincubated with 4-aminophenylmercuric acetate and trypsin to activate the enzyme prior to assay. Type IV collagen, purified from human placentas and radiolabeled with [1-14C] acetic anhydride, was used as the substrate. The enzyme activity was measured at pH 7.5 and inhibited by treatment with ethylenediaminetetraacetic acid or heat. The assay of type IV collagen-degrading enzyme in human serum might be useful for estimating the degradation of type IV collagen.