Characterization of the Interaction Between Lantibiotics,Nisin and Duramycin,and β-Lactoglobulin by Affinity Capillary Electrophoresis

Affinity capillary electrophoresis was used to study quantitatively the noncovalent interactions between β-lactoglobulin (β-LG), a milk whey protein, and two lantibiotics, nisin (a dairy biopreservative lantibiotic) and duramycin (a bovine mastitis treatment lantibiotic). The study involved measuring the change in effective electrophoretic mobility of the lantibiotic as the concentration of β-LG in the background electrolyte is increased. Nonlinear regression analysis was used to model the dependence of the effective mobility of the lantibiotic on β-LG concentration in the BGE. Using this approach, binding constants were determined to be 3.1 (±0.2) × 10⁸ M^?1 for nisin and 2.2 (±0.1) × 10⁸ M^?1 for duramycin. Both binding constants were comparable indicating the similarity of affinity properties of nisin and duramycin towards β-LG. These results demonstrate that affinity capillary electrophoresis is a suitable method for characterizing the interaction between lantibiotics and β-LG.