Stimulation and inhibition of fibril formation by a peptide in the presence of different concentrations of SDS

Sodium dodecyl sulphate (SDS), a detergent that mimics some characteristics of biological membranes, has been found to affect significantly fibril formation by a peptide from human complement receptor 1. In aqueous solution the peptide is unfolded but slowly aggregates to form fibrils. In sub-micellar concentrations of SDS the peptide is initially a-helical but converts rapidly to a P-sheet structure and large quantities of fibrils form. In SDS above the critical micellar concentration the peptide adopts a stable a-helical structure and no fibrils are observed. These findings demonstrate the sensitivity of fibril formation to solution conditions and suggest a possible role for membrane components in amyloid fibril formation in living systems. (C) 2002 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.