Intensities and other spectral parameters of infrared amide bands of polypeptides in the β- and random forms

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Abstract

The intensities and other spectral parameters of the main components of infrared amide bands for the random and anti-parallel pleated sheet forms have been determined for poly-S-carbobenzoxymethylcysteine, poly-S-carboxymethylcysteine, polylysine and silk fibroin of Bombyx mori in heavy water solutions and in organic solvents. Assuming that the optical spectra of these two types of structure are additive, the method was proposed for determining relative contents and molar absorption coefficients of amide I band. Integral intensity and maximum frequency values of the main components of the amide I band for all the samples in the β-form turned out to be specific. In contrast to this the integral intensity of the band of amide I in the random coil form varied within certain limits, while the main maximum frequency for all samples remained the same.

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