title: Studies on the peptide bond specificity and the essential groups of an acid proteinase from Aspergillus fumigatus.
abstract: The specificity and mode of action of an acid proteinase from A. fumigatus was studied with B-chain of insulin, angiotensin II and bradykinin. With reference to the known structure of the B-chain of insulin and angiotensin II, the major sites of action were determined. Acid proteinase of A. fumigatus hydrolyzed primarily three peptide bonds in the B-chain of insulin viz. i. His(5)-Leu(6); ii. Tyr(16)-Leu(17) and iii. Phe(24)-Phe(25) bonds. Additional cleavages of the bonds His(10)-Leu(11) and Leu(15-Tyr(16) were also noted. Primary splitting sites, Tyr(16)-Leu(17) and Phe(24)-Phe(25) were identical with those reported in the work of porcine pepsin C (EC 3.4.23.3). Hydrolysis of angiotensin II was observed at Tyr(4)-Ile(5) bond. The acid proteinase was found not to be inactivated by EDTA, DEP and PCMB. The pepsin specific inhibitors viz. DAN/Cu II and EPNP showed quite appreciable inhibition, while SDS completely inactivated this acid proteinase.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000804:Angiotensin II / Q000378:metabolism; D016282:Aspartic Acid Endopeptidases; D001232:Aspergillus fumigatus / Q000201:enzymology*; D010450:Endopeptidases / Q000378:metabolism*; D006868:Hydrolysis; D007328:Insulin / Q000378:metabolism; D010455:Peptides / Q000032:analysis; D011480:Protease Inhibitors
chemical_list: D000596:Amino Acids; D007328:Insulin; D010455:Peptides; D011480:Protease Inhibitors; D000804:Angiotensin II; D010450:Endopeptidases; D016282:Aspartic Acid Endopeptidases