The specificity of cathepsin B. Hydrolysis of glucagon at the C-terminus by a peptidyldipeptidase mechanism.
The manner in which human liver cathepsin B (EC 3.4.22.1) digests glucagon was determined. After reaction of the proteinase with the substrate for 24h, more than 15 products were formed. During the first 7 h of reaction, eight products were formed; seven of these were dipeptides that originated from the C-terminal portion of the glucagon molecule, whereas the eighth peptide was the remaining large fragment of the hormone, consisting of residues 1-19. Measurement of the rate of formation of the products showed that cathepsin B degraded glucagon by a sequential cleavage of dipeptides from the C-terminal end of the molecule. Cathepsin B from both rat liver and bovine spleen was shown to hydrolyse glucagon by the same mechanism.
D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002403:Cathepsins / Q000378:metabolism*; D002417:Cattle; D002852:Chromatography, Ion Exchange; D004590:Electrophoresis, Paper; D005934:Glucagon / Q000378:metabolism*; D006801:Humans; D008099:Liver / Q000201:enzymology; D010446:Peptide Fragments / Q000032:analysis; D051381:Rats; D013154:Spleen / Q000201:enzymology
D000596:Amino Acids; D010446:Peptide Fragments; D005934:Glucagon; D002403:Cathepsins