DIGESTIBILITY AND PEPTIDE PATTERNS OF MODIFIED LYSOZYME AFTER HYDROLYZING BY PROTEASE

In this study, lysozyme was modified by glucose in the dry state (50 d egrees C, RH 75%) and the peptide patterns were investigated using HPL C after hydrolyzing by the pepsin-pancreatin system. Native or modifie d lysozyme was also administered to rats to clarify digestibility and absorbability in vivo. The digestibility of lysozyme modified by gluco se decreased depending on reaction time. In vitro, when lysine residue of lysozyme was modified by glucose at a level of about 50%, the gene rated peptide patterns with molecular weights (MW) below 3,000 Da were similar to that of native lysozyme, and the yields of peptides from m odified lysozyme were lower than those of native lysozyme. However, th ere are some differences between the hydrolysate patterns of native an d modified lysozymes of MW over 10,000 Da, and the yields of these pep tides from modified lysozyme are higher than those from native lysozym e. In vivo, the percentage of 30 d-modified lysozyme remaining in rat digestive tracts after 90 min of administration was 11% of the dosage as compared with 0.4% for native lysozyme. However, the digestive pept ide patterns of native or modified lysozymes in the rat small intestin e were also similar to those of the control. Consequently, it is estim ated that modified lysozyme was digested as easily as native lysozyme when the degree of modification of lysine residue by glucose was about 60% even in vivo.