The influence of β-casein glycation on its interaction with natural and synthetic polyelectrolytes

The interaction of proteins with polyanions and polycations is involved in many processes in living cell. These proteins undergo posttranslational modifications such as glycation, which change electrostatic interactions of the modified protein with other macromolecules and can significantly alter its behavior. In the present work, we investigated the influence of glycation by methylglyoxal of intrinsically disordered milk protein, β-casein, on its interaction with natural and model polyelectrolytes. Irrespective to glycation, β-casein interacted with polycation, forming large precipitating aggregates. Efficient interaction has been observed also for relatively hydrophobic polyanion, poly(styrene sulfonate). Interaction with hydrophilic sulfated polymer, heparin, as well as polyphosphate and polycarboxylate anions was much less pronounced. Significant weakening of the binding due to glycation of β-casein was observed for polycytidylate and poly(acrylate) but not for other polymers. The obtained results are important for the use of anionic polymers in milk food chemistry, especially for heat treatment in the presence of sugars.