Hydrolases;
Acting on peptide bonds (peptidases);
Aspartic endopeptidases
Reaction(IUBMB)
Hydrolysis of proteins with broad specificity, cleaving Phe24!Phe, but not Leu15-Tyr and Phe25-Tyr in the B chain of insulin
Comment
A second endopeptidase from Scytalidium lignicolum (see scytalidopepsin A) that is insensitive to pepstatin and methyl 2-diazoacetamidohexanoate. 1,2-Epoxy-3-(p-nitrophenoxy)propane reacts with Glu53, which replaces one of the aspartic residues at the active centre. One of the smallest aspartic endopeptidases active as the monomer, with Mr 22,000. Similarly inhibitor-resistant endopeptidases are found in the basidiomycetes Lentinus edodes [1] and Ganoderma lucidum [3], and in Polyporus tulipiferae [4], a second endopeptidase distinct from polyporopepsin, but these are of typical aspartic endopeptidase size, Mr about 36,000. Type example of peptidase family G1.
Tsuru D, Shimada S, Maruta S, Yoshimoto T, Oda K, Murao S, Miyata T, Iwanaga S.
Title
Isolation and amino acid sequence of a peptide containing an epoxide-reactive residue from the thermolysin-digest of Scytalidium lignicolum acid protease B.