Calf tendon procollagen peptidase: its purification and endopeptidase mode of action

The procollagen peptidase activity of calf tendon has been purified. The enzyme has a high degree of specificity for native procollagen and converts both pro alpha1 and alpha2, to alpha1 and alpha2, respectively. The purified enzyme is an endopeptidase which excises the amino terminal peptide extensions of the precursor chains in block; the molecular size and amino-acid composition of the excised peptides compare favorably with those predicted in previous reports. Antisera to the enzyme and to procollagen have been prepared and have been used to characterize the enzyme, the enzymatically excised peptides, and the enzyme-peptide complex in reaction mixtures.