Peptide spectra

This benefit comes at a cost, which arises from significantly reduced S/N and some interpretive difficulty as compared to IR. Developments on the latter front are bringing the theoretical prediction capability of VCD for small molecules to a level demonstrably superior to that for ECD (Freedman and Nafie, 1994 Stephens et al., 1994 Stephens and Devlin, 2000), especially for peptide spectra (Kubelka et al., 2002). Most previous protein applications of VCD used empirically based analyses (Keiderling, 1996, 2000). Theoretical methods are limited when applied to large molecules such as proteins however, a hybrid approach using ab initio determination of spectral parameters with modest-sized molecules for transfer to large peptides has made simulation of spectra for large peptides possible (Bour et al., 1997 Kubelka et al., 2002). Theoretical techniques for simulation of small-molecule VCD are the focus of several previous reviews (Stephens and Lowe, 1985 Freedman and Nafie,... 

As the series of peptide spectra already presented has shown,... 

A number of Fi region-selected inverse-detected 2D NMR experiments have been reported. One of the earliest (Davis 1989) took a different approach from more recent reports. Recognizing the need for higher digital resolution in assigning peptide spectra, Davis approached Fi region selection... 

I.R. studies are generally not affected by these problems. Especially the spectral regions of the conformationally sensitive amide absorption bands are studied by I.R. spectroscopy. In practice, the best information is obtained from spectra of a diluted solution of small peptides. Spectra in the solid state or from polypeptides show low resolution of interesting absorption bands. 

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