McSweeney PL, Olson NF, Fox PF, Healy A. Proteolysis of bovine alpha s2-casein by chymosin.
ZEITSCHRIFT FUR LEBENSMITTEL-UNTERSUCHUNG UND -FORSCHUNG 1994;
199:429-32. [PMID:
7892751 DOI:
10.1007/bf01193267]
[Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Proteolysis of bovine alpha s2-casein by chymosin (E. C. 3.4.23.4) in solution in 100 mM Na phosphate buffer, pH 6.5, at 30 degrees C was studied by reversed-phase (RP)-HPLC and urea-polyacrylamide gel electrophoresis (PAGE). Chymosin hydrolyzed alpha s2-casein in solution to eight peptides detectable by urea-PAGE. Peptides soluble in acetate buffer, pH 4.6, were isolated by RP-HPLC on a C18 column using an acetonitrile/water gradient and identified from their N-terminal amino acid sequence. The chymosin cleavage sites were at the bonds Phe88-Tyr89, Tyr95-Leu96, Gln97-Tyr98, Tyr98-Leu99, Phe163-Leu164, Phe174-Ala175 and Tyr179-Leu180. Chymosin cleavage sites were restricted to the hydrophobic regions of the molecule. The bond-type in alpha s2-casein cleaved by chymosin was in agreement with that found to be susceptible to chymosin in other caseins. The primary site of chymosin action on alpha s2-casein appeared to be at Phe88-Tyr89.
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