Abstract
Bovine serum albumin (BSA) was chemically treated in the presence or absence of L-cysteine (Cys) after the cleavage of hydrogen bonds by urea and reduction of disulfide linkages by sodium tetrahydroborate. The reduced BSA was re-oxidized with hydrogen peroxide and Cys treated- or non-Cys treated- BSA was obtained (C-BSA or NC-BSA). The percentage of thiol groups modified in C-BSA was 73.6%. The peptic digestibility of BSA was markedly improved by chemical treatment in the presence of Cys. The pancreatic and tryptic digestibility of BSA was higher in the order of C-BSA>NC-BSA>native BSA. SDS-PAGE confirmed that chemical treatment with Cys improved the digestibility of BSA and facilitated protein fragmentation into small molecular weight peptides by protease. Further, enzyme-linked immunosorbent assay showed that the antigenicity of the tryptic digests of BSA was reduced about one-tenth by the chemical treatment with Cys. This result indicated that the change in conformation of BSA decreased the antigenicity through enhancement of protease susceptibility.
