Purification and identification of immunomodulating peptides from enzymatic hydrolysates of Alaska pollock frame.

To prepare immunomodulating peptides from Alaska pollock frame (APF) hydrolysates, trypsin was employed for enzymatic hydrolysis, and the immunomodulating activities of the hydrolysates were studied using splenic lymphocytes proliferation assay. The highest activity of the hydrolysates was reached when DH ranged from 15% to 18%. The peptide fractions which exhibited the highest activity were further purified using ion exchange chromatography, gel filtration chromatography, and RP-HPLC. The peptides were identified using nano-LC-ESI mass spectrometry. Finally, three immunomodulating peptides were obtained, and the amino acid sequences were Asn-Gly-Met-Thr-Tyr, Asn-Gly-Leu-Ala-Pro, and Trp-Thr, respectively. The lymphocyte proliferation rates were 35.92%, 32.96%, and 31.35% in the presence of 20 μg/ml purified peptides, respectively. Therefore, the results demonstrated that the APF proteins hydrolysates prepared by trypsin could serve as a source of peptides with immunomodulating activity. It provided a scientific basis for the preparation of immunomodulating peptides.