Protective interactions of dairy peptides with fibril structures and relevance to Alzheimer's Disease

Abstract

Selected dairy caseins have been shown to have capacity for chaperone-like regulation of folding pathways of other caseins, specifically in preventing development of fibrillar aggregates of beta sheet structure. An assay based on fibril formation by reduced and carboxymethylated-kappa casein (RCM-kCn) was thus used to screen for anti-fibril activity among a selection of dairy protein hydrolysates, in order to discover peptides with possible anti-fibril, chaperone activity. From the selection of eight dairy hydrolysates based on different dairy protein fractions, two of the hydrolysates of whey protein exhibited superior anti-fibril bioactivity against RCM-kCn and amyloid beta (Aβ), the peptide associated with fibrillar plaque deposits in brains of Alzheimer's Disease patients. It is also possible that the chaperone-like activity responsible for anti-fibril activity may exert protective bioactivity in other protein folding diseases involving proteins other than Aβ, accessible from the periphery. Antifibril peptides may also confer stability and prevent aggregation of thermally denatured dairy protein systems during processing. These results demonstrate the capacity of dairy peptides to inhibit Aβ fibril formation in vitro and justifies further investigation of this property as a novel class of bioactivity for dairy peptides.