Molecular mechanism of Golden Pomfret myofibrillar protein digestion inhibition by malondialdehyde-mediated oxidation based on peptidomics analysis

This study investigated the effects of malondialdehyde (MDA) induced oxidation on the digestion of the Golden Pomfret myofibrillar protein. Results showed that protein digestibility decreased significantly with increased MDA concentration (<i>P</i> < 0.05). Compared with the control group, the digestibility of proteins subjected to treatment with 10 mM MDA declined from 98.66 % to 44.41 %. Moreover, the gastric and intestinal digestibility constants decreased from 6.55 and 7 to 2.12 and 0.72, respectively. Notably, MDA detaches from MP during digestion, and MDA shields the cleavage sites of pepsin and trypsin on tryptophan, arginine, and lysine. Compared to the control group, the number of peptides in the digestive products of proteins treated with 10 mM MDA dropped from 2870 to 901, the total peptide count decreased from 4399 to 1667, and new peptides emerged. These results indicated that the digestion of oxidized protein mediated by MDA was inhibited, and this inhibition of MP digestion was irreversible. Notably, myosin was the protein most profoundly impacted by MDA.