Abstract: Paphia undulate muscles were hydrolyzed with papain and the hydrolysates after hydrolysis for 1, 2, 3, 4, 5 h and 6 h were analyzed by SDS-PAEG and LC-MS/MS. The results revealed that the molecular mass distribution of peptides in Paphia undulate muscle hydrolysates was mostly concentrated on 100, 50 kD and 2 kD during the first 3 hours of the hydrolysis, most of them large or small peptides. No substantial difference in the molecular mass distribution of peptides, which was mostly between 400 D and 600 D, was observed among the 4 h, 5 h and 6 h hydrolysates, suggesting that 4 h was the end point of the hydrolysis.

Key words: Paphia undulate, bioactive peptide, SDS-PAGE, LC-MS