Adsorption characteristics of tryptic fragments of bovine beta-lactoglobulin on a stainless steel surface

As a strategy for the analysis of the mode of protein adsorption onto stain less steel surfaces, peptides obtained by tryptic digestion of bovine beta- lactoglobulin were subjected to adsorption experiments after identification of their primary structures. In the presence of I mM KOH, the peptides wer e scarcely adsorbed onto the surfaces of stainless steel particles from the peptide mixture. The adsorption experiments on isolated peptides showed th at the affinities of the peptides for stainless steel surfaces in the prese nce of 1 mM HNO3 were significantly different from each other. Peptides wit hout any acidic amino acid residues were scarcely adsorbed onto the surface , whereas some peptides with acidic amino acid residues were found to be ir reversibly adsorbed onto the surfaces in the acidic pH region. As for the l atter peptides, the amount adsorbed on the surface increased with increasin g ionic strength. These results indicated that the carboxyl groups on the s ide chains of the peptides play an important role in the adsorption. Furthe rmore, the adsorption behavior of beta-lactoglobulin itself was found to be very similar to that of one of the latter peptides.