Quantitative Estimation of α-Helix Coil Content in Bovine Serum Albumin by Fourier Transform-Infrared Spectroscopy

Abstract

Heat denaturation of albumin aqueous solution enables us to control the α-helix content to a reasonable level, and denatured albumin, whose conformation is different, can be obtained. Fourier transform-infrared absorption spectra in the amide I, II, and III band regions of these albumins have been measured and compared with each other. As a result, the characteristic frequencies associated with each conformation of α-helix, β-sheet, and random structure have been observed; moreover it has been newly proved that the intensity ratio of the amide II band to the amide I band depends on the α-helix content in albumin. In this paper, we demonstrate that this intensity ratio is very useful for quantitative estimation of α-helix content in albumin and apply this method to analysis of ATR spectra of albumin adsorbed on polyethylene surface.