Thermal Perturbation Difference Spectroscopy and Temperature-Dependent Conformational Transitions of Proteins

Abstract

When studying protein molecules in different conformational states, a high sensitivity of the method is required to describe the effects of protein conformation on the spectra to be obtained. This may be achieved by the introduction of an externally controlled parameter producing the effect on absorption spectra and allowing one to record difference spectra of the same specimens with and without this effect. The temperature dependence of absorption spectra suggests the introduction of temperature as a parameter alteration in which causes perturbation. Indeed, if the temperature dependence is different for chromophore groups in various structural states, then the difference spectra obtained for the same preparations within a small temperature range will carry the information on the structural state of these groups in the protein molecule. This fact is valid only when the temperature change within the studied interval does not evoke protein conformational changes. Otherwise, an additional spectrum component arises, which is due to a conformational difference.