The influence of cations on alpha-lactalbumin amyloid aggregation

There is limited knowledge regarding alpha-lactalbumin amyloid aggregation and its mechanism. We examined the formation of alpha-lactalbumin amyloid fibrils (alpha-LAF) in the presence of cations (Mg2+, Ca2+, Na+, K+, NH4+, and Cs+) in the form of chloride salts at two concentrations. We have shown that studied cations affect the conformation of alpha-lactalbumin, the kinetics of its amyloid formation, morphology, and secondary structure of alpha-LAF in a different manner. The higher salts concentration significantly accelerated the aggregation process. Both salt concentrations stabilized alpha-lactalbumin's secondary structure. However, the presence of divalent cations resulted in shorter fibrils with less beta-sheet content. Moreover, strongly hydrated Mg2+ significantly altered alpha-lactalbumin's tertiary structure, followed by Na+, NH4+, K+, and weakly hydrated Cs+. On the other hand, Ca2+, despite being also strongly hydrated, stabilized the tertiary structure, supposedly due to its high affinity towards alpha-lactalbumin. Yet, Ca2+ was not able to inhibit alpha-lactalbumin amyloid aggregation. [GRAPHICS]