The effect of green synthesis silver nanoparticles (AgNPs) from Pulicaria undulata on the amyloid formation in α-lactalbumin and the chaperon action of α-casein

The formation and deposition of protein fibrillar aggregates in the tissues is associated with several neurodegenerative diseases such as Alzheimer's and Parkinson's disease. Molecular chaperones are a family of proteins that are believed to have the ability to inhibit protein aggregation. The present study examines the effect of different concentrations of green synthesis silver nanoparticles (AgNPs) from Pulicaria undulata L. on the aggregation of alpha-lactalbumin (alpha-LA) and the chaperone action of alpha(s)-casein. The effects of the AgNPs were determined by measuring light scattering absorption, fluorescence (ThT assay, intrinsic fluorescence assay and ANS binding assay), TEM, CD spectroscopy and SDS-PAGE. The results showed that AgNPs have the ability to prevent the aggregation of alpha-LA in a concentration-dependent manner. In fact, by increasing the concentration of AgNPs within a specified range, the adsorption and interaction between AgNPs and protein have increased and protein conformational changes and self-association decreased, thus amyloid aggregation is prevented. Our results also showed that alpha-casein effectively prevented the aggregation of the alpha-lactalbumin which increased in the presence of the AgNPs. Standard experimental results, however, proved that nanoparticles had no effect on the structure and hence the chaperone ability of alpha-casein. Our findings showed that AgNPs can prevent protein aggregation and have no effect on the chaperone ability of alpha(s)-casein. In the main, results of this study show that biosynthesized AgNPs mediated by Pulicaria undulata L has the capability in inhibiting amyloid fibril formation and thus could be consider as a therapeutic agent in the treatment of amyloidosis disorders. (C) 2017 Elsevier B.V. All rights reserved.