Cys(SO3H), Glu21Arg and Asn3Gln, although not Gln4-His
Reaction: Preference for hydrophobic residues at P1 and P1'. Action on the B chain of insulin is generally similar to that of pepsin A, but it also cleaves Leu6Cys(SO3H), Glu21Arg and Asn3Gln, although not Gln4-His
Other names: Acrocylindrium proteinase; Acrocylindrium acid proteinase
Comments: From the imperfect fungus Acrocylindrium sp. Has a very low pH optimum on casein of 2.0. In peptidase family A1 (pepsin A family). Formerly EC 3.4.99.1 and included in EC 3.4.23.6
Links to other databases: BRENDA, EXPASY, KEGG, MEROPS, Metacyc, CAS registry number: 37288-84-9
References:
1. Uchino, F., Kurono, Y. and Doi, S. Purification and some properties of crystalline acid protease from Acrocylindrium sp. Agric. Biol. Chem. 31 (1967) 428-434
2. Ichihara, S. and Uchino, F. The specificity of acid proteinase from Acrocylindrium. Agric. Biol. Chem. 39 (1975) 423-428
3. Takahashi, K. and Chang, W.-J. The structure and function of acid proteases. V. Comparative studies on the specific inhibition of acid proteases by diazoacetyl-DL-norleucine methyl ester, 1,2-epoxy-3-(p-nitrophenoxy)propane and pepstatin. J. Biochem. (Tokyo) 80 (1976) 497-506. [PMID: 10290]