Abstract: The present invention is directed to the isolation and identification of the nucleic acid sequence encoding C-proteinase, the recognition of such protein's activity and applications, and tools, processes, and methods of use thereof. The invention is further directed to the identification of molecules modulating C-proteinase's activity, and methods, processes and tools therefor. In a more specific aspect, the invention is directed to peptides resembling the C-proteinase recognition site of procollagen. Such peptides may be employed as modulators of C-proteinase activity, by, for example, acting as competitive inhibitor, and may be employed for the treatment of disorders which involve unregulated production of collagen. Furthermore, such peptides may be employed as C-proteinase substrates for screening of molecules to identify compounds which modulate C-proteinase's activity.