Figure 6
Sequence segments of α-Syn critical for the formation of helical intermediates probed by Trp fluorescence study.
(A) Trp emission spectra showing gradual blue shift of λmax of for V3W (left), V71W (middle) and A140W (right) during RC → α-helix → β-sheet transition. (B) Changes of Trp fluorescence intensity maxima (λmax) during helix-rich intermediate and amyloid formation by Trp-substituted WT α-Syn. The large λmax change was evident for V71W and A140W during helix → β-sheet transition. (C) Modified Stern-Volmer plots of Trp quenching for [V3W]α-Syn, [V71W]α-Syn and [A140W]α-Syn using acrylamide. Quenching of site-specific Trp mutants at three different stages of incubation were carried out (freshly prepared low molecular weight (LMW), helix-rich intermediate and at the time of first β-sheet appearance (β-sheet)). F indicates maximum Trp fluorescence intensity in presence of different acrylamide concentrations and F0 stands for maximum Trp fluorescence intensity in absence of acrylamide. (D) Stern-Volmer quenching constants of site-specific Trp variants of freshly prepared LMW, helix-rich intermediate and immediately after conversion to β-sheet.
