Fig. 3: Heme causes a major reduction in the antiparallel β sheet component of fibril-forming aggregates.

Deconvoluted FT-IR spectra of 24 h oligomers incubated a in the absence of heme; or b in presence of heme from the beginning of incubation period (oligomers₁, preincubation); c depicts the IR spectrum of oligomers₂ formed when 48 h prefibrillar and fibrillar aggregates were treated with heme, postincubation. d Addition of heme causes a drastic reduction in the antiparallel β sheet component (bands at ~1680–90 cm⁻¹, Panels a–c, illustrated in red) of the resulting oligomeric population. The bands depicted in green denote the parallel β sheet component (1622–1638 cm⁻¹). Error bars are ±SEM obtained from four independent experiments. Second derivatives of the FT-IR spectra (Supplementary Fig. 5, SI) have been used to determine individual peaks.