Circular dichroism and UV-resonance Raman investigation of the temperature dependence of the conformations of linear and cyclic elastin

We used electronic circular dichroism (CD) and UV resonance Raman (UVRR) spectroscopy at 204 nm excitation to examine the temperature dependence of conformational changes in cyclic and linear elastin peptides. We utilize CD spectroscopy to study global conformation changes in elastin peptides, while UVRR is utilized to probe the local conformation and hydrogen bonding of Val and Pro peptide bonds. Our results indicate that at 20 degrees C cyclic elastin predominantly populates distorted beta-strand, beta-type II and beta-type III turn conformations. At 60 degrees C, the beta-type II turn population increases, while the distorted beta-strand population decreases. Linear elastin predominantly adopts distorted beta-strand and beta-type III turn conformations with some beta-type II turn population at 20 degrees C. Increasing temperature to 60 degrees C results in a small increase in the turn population.