Zusammenfassung
Die Proteolyse von Bovinem αs2-Casein durch Chymosin (E. C. 3.4.23.4) in 0.1 M Phosphatpuffer bei pH 6,5 und 30 °C wurde chromatographisch und elektrophoretisch verfolgt. Es resultierten sieben Spaltstellen, diese wurden identifiziert. Alle Spaltstellen liegen in hydrophoben Regionen. Am schnellsten wird die Bindung Phe88-Tyr89 gespalten.
Abstract
Proteolysis of bovine αs2-casein by chymosin (E. C. 3.4.23.4) in solution in 100mm Na phosphate buffer, pH 6.5, at 30 °C was studied by reversed-phase (RP)-HPLC and urea-polyacrylamide gel electrophoresis (PAGE). Chymosin hydrolyzed αs2-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 αs2-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 αs2-casein appeared to be at Phe88-Tyr89.
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McSweeney, P.L.H., Olson, N.F., Fox, P.F. et al. Proteolysis of bovine αs2-casein by chymosin. Z Lebensm Unters Forch 199, 429–432 (1994). https://doi.org/10.1007/BF01193267
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DOI: https://doi.org/10.1007/BF01193267