LVFFARK conjugation to poly (carboxybetaine methacrylate) remarkably enhances its inhibitory potency on amyloid β-protein fibrillogenesis

Abstract

Fibrillar aggregation of amyloid β-protein (Aβ) is complicated in the pathological process of Alzheimer's disease (AD). Therefore, inhibition of Aβ aggregation is considered as a promising strategy for the precaution and treatment of AD. Ac-LVFFARK-NH2 (LK7) has been recognized as an inhibitor of Aβ aggregation, but its propensity to aggregation and strong cytotoxicity limited its applications. Thus, we have herein conjugated LK7 to a zwitterionic polymer, poly (carboxybetaine methacrylate) (pCB), and synthesized three LK7@pCB conjugates of different degrees of substitution (DS). The conjugation eliminated the aggregation propensity of LK7 and the conjugates self-assembled into micelles. It revealed that the LK7@pCB micelles inhibited Aβ fibrillogenesis and mitigated the amyloid cytotoxicity more efficiently than free LK7. Structural analysis indicated that LK7@pCB micelles suppressed the conformational transition of Aβ42 into β-sheet structure and thus changed its aggregation pathway. The superiority of LK7@pCB is considered due to the integrated functions of LK7 and pCB. Namely, high local LK7 concentration in the micellar interior significantly enhanced the interactions between Aβ42 and LK7, and the dense hydration layer on pCB strongly stabilized the bound Aβ on LK7 anchored on pCB, restricted its conformational transition and the following on-pathway fibrillation.