INTERPRETATION AND APPLICATIONS OF THERMAL DIFFERENCE SPECTRA OF PROTEINS

Abstract

The technique of thermal perturbation difference spectroscopy for examining chromophores in proteins has been set on a more acceptable theoretical and experimental foundation. (i) The origins of the thermal effect have been analysed to explain changes in spectral band width and wavelength for simple chromophores in various solvents. Comparison with theoretical curves shows that the effect of heating chromophore solutions is mainly spectral broadening coupled with an almost negligible blue shift. The apparently anomalous behavior of tryptophan and tyrosine in aqueous solvents, where the main effect is a red shift on heating, is traced to hydrogen bonding with water. A model in which tyrosine ..