Effect of Thermally Induced Structural Transitions on the Ultra-Violet Fluorescence of Proteins

Abstract

IT has been shown by Weber^1,2 and by Teale³ that the ultra-violet fluorescence spectra of proteins containing tryptophan resemble that of tryptophan itself. The wide variations found by Teale and Weber among different proteins as to both quantum yields and polarization spectra indicate that the local environment of the tryptophan groups is an important factor in their emission properties. Thus it is reasonable to predict that any major structural transition of a protein which results in some important modification in the environment of its tryptophans would be reflected by alterations in its emission spectra. This communication will be confined to fluorescence changes resulting from thermally induced structural transitions. As the three proteins selected all contain tryptophan, it is probable, in view of the results of Teale³, that virtually all the observed emission at 340 mµ (activated at 290 mµ) arises from this group.