Formation of cytotoxic α-lactalbumin / sodium oleate complexes: Concentration and temperature effects

Cytotoxic complexes may be formed by mixing whey proteins and oleic acid or sodium oleate. The present study investigated the kinetics of complex formation when the whey protein α-lactalbumin (α-LA) is mixed with sodium oleate. Intrinsic fluorescence showed that the complex formed at room temperature during the mixing of α-LA and sodium oleate. However, some of the structural changes brought about by the binding of the sodium oleate can be reversed by dialysis, when loosely bound oleate is removed. During dialysis, solutions with lower protein concentrations had reduced buffering capacity, and so the pH decreased more; this decrease in pH was correlated with a loss of oleate from the complex. The cytotoxicity of all the samples produced in this study was strongly correlated with the amount of oleate bound in the complex, confirming previous studies that suggested that oleic acid is the cytotoxic agent in the complex.