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Vibrational circular dichroism (VCD) spectra provide information on the solution conformations of chiral molecules. The CH-, OH-, NH-, and C equals O-stretching VCD features are particularly useful conformational probes. Molecules of pharmaceutical interest studied by VCD include biomimetic iron carriers, unsaturated peptides, the anticancer drug taxol and a series of type I antiarrhythmic drugs.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Vibrational circular dichroism (VCD) spectra have been recorded in the NH and C equals O stretching regions for a series of tripodal peptides and peptides containing an unsaturated residue, in order to obtain information about solution conformations.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Fourier transform ir vibrational circular dichroism (VCD) spectra in the amide I′ region of poly(L-lysine) in D2O solutions have confirmed the existence of three distinct conformational states and an unordered conformational state in this homopolypeptide. Characteristic VCD spectra are presented for the right-handed α-helix, the antiparallel β-sheet, an extended helix conformation previously referred to as the so-called “random coil,” and a completely unordered conformation characterized by the absence of any amide I′ VCD. VCD for the antiparallel β-sheet in solution and the unordered chain conformation are presented for the first time. Each of the four different VCD spectra is unique in appearance and lends weight to the view that VCD has the potential to become a sensitive new probe of the secondary structure of proteins in solution.

Vibrational circular dichroism (VCD) has been used to determine the solution structures of three tripodal peptide molecules. The interchain hydrogen bonding is shown to be oriented in a clockwise direction (from C=0 to NH) by application of the coupled oscillator mechanism in the carbonyl stretching region. The carbonyls of the terminal Boc groups are found to be oriented in a counterclockwise direction. Open chain conformations and dimers are also present in solution and contribute to the VCD spectra with monosignate intensity that is interpreted using the ring current mechanism.