The influence of cations on α-lactalbumin amyloid aggregation

There is limited knowledge regarding α-lactalbumin amyloid aggregation and its mechanism. We examined the formation of α-lactalbumin amyloid fibrils (α-LAF) in the presence of cations (Mg(2+), Ca(2+), Na(+), K(+), NH(4)(+), and Cs(+)) in the form of chloride salts at two concentrations. We have shown that studied cations affect the conformation of α-lactalbumin, the kinetics of its amyloid formation, morphology, and secondary structure of α-LAF in a different manner. The higher salts concentration significantly accelerated the aggregation process. Both salt concentrations stabilized α-lactalbumin's secondary structure. However, the presence of divalent cations resulted in shorter fibrils with less β-sheet content. Moreover, strongly hydrated Mg(2+) significantly altered α-lactalbumin's tertiary structure, followed by Na(+), NH(4)(+), K(+), and weakly hydrated Cs(+). On the other hand, Ca(2+), despite being also strongly hydrated, stabilized the tertiary structure, supposedly due to its high affinity towards α-lactalbumin. Yet, Ca(2+) was not able to inhibit α-lactalbumin amyloid aggregation. GRAPHIC ABSTRACT: [Image: see text] SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00775-022-01962-3.