Procollagen N-proteinase. Properties of the enzyme purified from chick embryo tendons.

Procollagen N-proteinase was purified about 3700-fold from chick embryo tendons. Electrophoresis of the protein after iodination and denaturation suggested it was homogeneous. However, the native enzyme could not be examined by gel electrophoresis, and therefore homogeneity of the preparation was not conclusively established. Antibodies to the enzyme completely inhibited activity and gave a single precipitant line by double immuno-diffusion. The Km for a native procollagen substrate was 0.3-0.5 microM. The same protein after denaturation inhibited activity. The enzyme did not cleave type III procollagen from human fibroblasts or a type IV procollagen from a mouse sarcoma. Ca2+ was required for maximal enzymic activity. The data suggested a second metal requirement, but this was not identified. Reducing agents and metal chelators inhibited activity, but there was little if any inhibition from several inhibitors of other neutral metalloproteinases.