A Saccharomyces cerevisiae cell membrane affinity screening method was developed to separate targeted
antimicrobial peptides from the pepsin hydrolyzate of bovine casein. S. cerevisiae cell membranes were
first immobilized on the surface of the silica gel to construct an affinity binding medium. A membranebinding
fraction was successfully screened by comparing the RP-HPLC fingerprint chromatograms of the
hydrolyzate before and after adsorption with the adsorption medium. The amino acid sequence of the
peptide was identified as LRLKKYKVPQL with the use of a matrix-assisted laser desorption/ionisation
quadrupole time-of-flight tandem mass spectrometer. The sequence corresponded to amino acid residues
99e109 of bovine aS1-casein. The results indicated that it is feasible to target screen antimicrobial
peptides from protein hydrolyzate using S. cerevisiae cell membranes. The influences of thermal treatment,
pH, ions, and enzymes on the activity of the purified peptide were also determined. The activity of
the peptide was relatively thermally stable and was pH dependent. It retained more than 90% of its
activity in the presence of 15% Naþ, Kþ and pepsin. Trypsin, proteinase K, divalent cation Mg2þ and Ca2þ
reduced the activity to different extents. The peptide also showed antibacterial effectiveness in fresh pear
juice. These observations provide further information on the application of protein-derived antimicrobial
peptides in food systems.