Application of the Factor Analysis to the Monitoring of the Changes in Protein Structure by Circular Dichroism

Abstract

Circular dichroism (CD) spectroscopy is a useful tool for the detection of changes in both the secondary and tertiary structure of proteins induced by processes such as, protein folding. Despite the big amount of information that the CD spectra contain, these changes are monitored using a selected and limited number of wavelengths. The choosing of these wavelengths is made as a function of an a priori hypothesis about the nature of the change (i.e the loss of a-helix secondary structure is monitored by the intensity of the band at 222 nm). In this work, we propose the use of Factor Analysis techniques for the study of the structural changes in proteins. This methods is based on the use of a family of computational and statistical techniques concerned to the isolation of sources of variation in an experimental data set, without any a priori assumption about the contribution of the different actors [1]. Among these techniques, a new multivariate curve resolution method has been shown to be a powerful method for the study of the conformational changes using spectrophotometric techniques [2]. Here we study the possibilities of the multivariate curve resolution method for the CD monitoring of the structural changes in the formation of the pH-induced molten globule state of α-lactalbumin.