Novel Approaches to Protein Structural Analyses Using Combinations of Optical Spectroscopic Methods (Electronic and Vibrational Circular Dichroism and Ftir Studies)

Abstract

We have developed a general approach for optimization of structural information derivable from a combination of protein vibrational and electronic circular dichroism (VCD, ECD) and FTIR spectra which goes beyond the traditional interpretation of these spectra in terms of the fractional composition (FC) of different secondary structure types. This approach stems from our observation [1] that for all these methods, the optimal prediction of the protein secondary structural composition requires reduction of the available spectral information. In other words, there are observable spectral features in protein spectra that are related to other structural features of the protein. We have first focussed on structural factors that might induce observable spectral changes in the optical spectra. Novel structural descriptors that can quantify these structural factors were developed for proteins whose structure is known from x-ray crystallography. Then a systematically obtained set of various types of optical spectra was measured for a reference set of proteins. Finally mathematical algorithms were developed for determination of relationship between the spectra and the selected structural descriptor.