Protease susceptibility of β-lactoglobulin adsorbed on stainless steel surface as evidence of contribution of its specific segment to adsorption

β-Lactoglobulin (β-Lg) is a major constituent of fouling deposits in the dairy industry. To determine the interaction between β-Lg and stainless steel surfaces, β-Lg irreversibly adsorbed on stainless steel particles was subjected to lysyl endopeptidase treatment and the course of fragmentation was compared with that observed for β-Lg in solution. The results showed a distinct difference between the courses of fragmentation: a fragment (residues 102-135) was liberated readily from β-Lg in solution but scarcely from β-Lg irreversibly adsorbed on stainless steel particles. This result strongly suggests that residues 102-135 include a segment primarily responsible for the interaction of β-Lg with stainless steel surfaces. This supports our previous results [Sakiyama et al., J. Biosci. Bioeng., 88, 536-541 (1999)] that showed that residues 125-135 of β-Lg have a strong affinity toward stainless steel surfaces and probably a major contribution to the adsorption of β-Lg.