Analysis of the binding mechanism of Trp-P-1 to Lactococcus lactis subsp. actis strain H1 and Lactococcus lactis subsp. cremoris strain H12 cells

Abstract

The binding mechanism of Trp-P-1 to Lactococcus lactis subsp. lactis strain H1 and Lactococcus lactis subsp. cremorisstrain H12 isolated from starter culture of Scandinavian traditional ropy sour milk “Langfil” was investigated. Binding of cells with Trp-P-1 was affected by altering pH in both strains. The strongest binding was observed at pH5-6, and the binding ability decreased below pH5 and above pH 6. The surface charges of strain H1 and H12 cells were determined by colloid titration. The isoelectric point was pH1.7 in both strains, and the negative charge of cells increased above the pH. The pKa of Trp-P-1 was 7.7. These results suggest that the binding mechanism of Trp-P-1 to both strains H 1 and H12 results from a cation-exchange effect.