Spectroscopic detection of β ‐sheet structure in nascent Aβ oligomers

Deep‐UV resonance Raman (UVRR) spectroscopy and circular dichroism (CD) were employed to study the secondary structure of Aβ(1–42) in fresh samples with increasing fractions of oligomeric peptide. A feature with a minimum at ～217 nm appeared in CD spectra of samples containing oligomeric Aβ(1–42). UVRR spectra more closely resembled those of disordered proteins. The primary difference between UVRR spectra was the ratio of the 1236 cm^–1 to 1260 cm^–1 amide III peak intensities, which shifted in favor of the 1236 cm^–1 band as the fraction of oligomeric peptide increased. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)