TRYPTIC HYDROLYSIS OF ESTERIFIED BETA-CASEIN AND BETA-LACTOGLOBULIN

Beta-Casein and beta-lactoglobulin have been esterified by methanol or ethanol in the presence of HCl, and the esterified derivatives obtain ed (40 to 55 % of the carboxyl groups substituted) have been hydrolyse d by trypsin. Tryptic peptides of the 2 proteins have been purified an d identified on the basis of their amino acid composition and the N-te rminal sequence. Ethylation of beta-lactoglobulin influences the split ting of the Lys60-Trp61 and Arg148-Leu149 bonds. No such influence is observed in case of modified in close proximity beta-casein cleavage s ites. It is possible that the more stringent structural factors play a role for beta-lactoglobulin. Analysis of the obtained results of the tryptic hydrolysis of these 2 different proteins in esterified forms s how that several mostly atypical new cleavage sites are activated (Gln -Thr; Ser-Glu; Ser-Leu; Tyr-Gln; Val-Leu; Met-His). The wide populatio n of oligopeptide esters obtained besides new atypically cleaved produ cts may show different biological/physiological properties.