title: Vibrational circular dichroism spectra of proteins in the amide III region: measurement and correlation of bandshape to secondary structure.
abstract: Vibrational circular dichroism (VCD) spectra have been measured for 23 globular proteins dissolved in H2O/phosphate buffer over the 1400 to 1100 cm(-1) region which encompasses the amide III mode. Spectral responses characteristic of the dominant secondary structure type were found as broad features at approximately 1300 cm(-1), with the extreme forms having positive VCD for highly helical proteins and negative VCD for highly sheet-containing proteins. Quantitative correlation with secondary structure was carried out using previously developed factor analysis and restricted multiple regression (FA/RMR) techniques. Since the absorbance intensity of the amide III mode is difficult to determine due to overlap with other transitions, an alternative, absolute intensity-independent, simple structural analysis method was used. A linear regression was developed between the fractional components of secondary structure for the protein set and the overlap integrals of the normalized spectra from the set with that of a selected protein. The results of this simple method are quite comparable to those of the FA/ RMR approach for analysis with amide III VCD. On the other hand, test calculations with the new method when used with electronic CD spectra are not as good as FA/RMR due to its more intensity-dependent relationship with secondary structure.
authors.affiliation: Department of Chemistry, University of Illinois at Chicago, 60607-7061, USA.
authors.forename: B I
authors.initials: BI
authors.lastname: Baello
authors.forename: P
authors.initials: P
authors.lastname: Pancoska
authors.forename: T A
authors.initials: TA
authors.lastname: Keiderling
mesh_terms: D002942:Circular Dichroism; D017433:Protein Structure, Secondary; D011506:Proteins / Q000737:chemistry*; D013223:Statistics as Topic
chemical_list: D011506:Proteins