Fast determination of the quantitative secondary structure of proteins by using some parameters of the Raman Amide I band

A very simple and fast method is presented for the quantitative determination of the secondary structural contents of a protein by Raman spectroscopy. We performed a statistical analysis of the correlations between the structural data on the one hand, obtained from X-ray crystallography, and the spectroscopic Raman data on the other, this has been for a large set of reference proteins. Such multi-parametric analysis permits one to express the percentages of structural contents of a protein in terms of some simple parameters of the experimental Raman Amide I band of that protein (maximum intensity frequency, width …). For instance, in a single parameter analysis, it was shown that the secondary structures can be estimated with accuracy from the knowledge of only the frequency of the peak of the Raman Amide I band. This, by using equations of the type: % structure = a ν(maximum) + b. a and b are coefficients calculated for each class of structure by using the least squares method. The best agreement between observed and calculated structures is obtained when using as parameters the frequency of the peak and both the left and right half band widths of the Amide I band.