Fourier Transform Vibrational Circular Dichroism In The amide I band Of Polypeptides

The Fourier transform vibrational circular dichroism (VCD) in the amide I region of poly-L-lysine in D20 solution has been investigated. Signals corresponding to the random coil, a-helix and antiparallel (3-sheet have been characterized. The spectrum of the a-helix shows the presence of three distinct features in agreement with previous results on deuterated polypeptides. We were able to detect the antiparallel β-sheet conformation in solution; the signal is unexpectedly large and monosignate in contrast to that predicted from exciton theory.