Procollagen peptidase: an enzyme excising the coordination peptides of procollagen.
A heritable connective tissue disorder of cattle, dermatosparaxis, is characterized by an extreme fragility of the skin and the presence of additional peptides at the N-terminal extremities of the collagen alpha chains, p-alpha(1) and p-alpha(2). The existence of an enzyme activity is demonstrated in normal connective tissues that is capable of cleaving these additional N-terminal peptides from dermatosparaxic collagen. The activity is demonstratable with dermatosparaxic collagen in solution, as well as with reconstituted dermatosparaxic collagen fibrils polymerized in vitro. It has a pH optimum of about 7.0 and is inhibited by EDTA and mercaptoethanol. Differences in K(m) and V(max) values exist depending on the substrate utilized, i.e., p-alpha(1) or p-alpha(2); and the presence of additional amounts of one substrate, p-alpha(1), alters the concentration requirement for the second substrate, p-alpha(2). The product of the excision reaction with p-alpha(1) as substrate is an equimolar amount of normal alpha(1) monomer; the product when p-alpha(2) is substrate is an equimolar amount of normal alpha(2) monomer. The enzyme is present in normal calf skin, tendon, aorta, cartilage, and lung; it can be demonstrated in the skin of rats and humans. The enzyme activity is absent in dermatosparaxic connective tissues, thus suggesting that dermatosparaxis is caused by the absence of a normal enzyme function rather than by the production of an abnormal collagen.
D000818:Animals; D001011:Aorta / Q000201:enzymology; D001921:Brain / Q000201:enzymology; D002356:Cartilage / Q000201:enzymology; D002417:Cattle; D003094:Collagen; D003095:Collagen Diseases / Q000201:enzymology* / Q000662:veterinary; D003238:Connective Tissue / Q000201:enzymology*; D004586:Electrophoresis; D010450:Endopeptidases / Q000032:analysis / Q000097:blood / Q000378:metabolism*; D006801:Humans; D007668:Kidney / Q000201:enzymology; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D008168:Lung / Q000201:enzymology; D009132:Muscles / Q000201:enzymology; D009206:Myocardium / Q000201:enzymology; D051381:Rats; D012867:Skin / Q000201:enzymology; D013154:Spleen / Q000201:enzymology; D013710:Tendons / Q000201:enzymology; D013950:Thymus Gland / Q000201:enzymology
D003094:Collagen; D010450:Endopeptidases