Purification and characterization of an immunomodulatory Peptide from bovine placenta water-soluble extract.

An immunomodulatory peptide was isolated from bovine placenta water-soluble extract and purified by consecutive chromatography on DEAE Sepharose CL-6B, Sephadex G-25, and Sephasil C18 column using lymphocyte proliferation assay to identify the active fractions. The immunomodulatory peptide showed a dose-dependent stimulating effect on lymphocyte proliferation. The isoelectric point of the immunodulatory peptide was determined to be 3.82 by capillary isoelectric focusing electrophoresis. The molecular mass of the immunomodulatory peptide was determined to be 2133.52 Da by mass spectrometry. The first 10 amino acid sequence of the immunomodulatory peptide was Tyr-X-Phe-Leu-Gly-Leu-Pro-Gly-X-Thr. This immunomodulatory peptide showed no significant homology with other immunomodulatory peptides. Additionally, it was thermostable, retaining about 60% of immune activity after incubating at 80 degrees C for 30 min.