Effect of hydrophobic environment on the resonance Raman spectra of tryptophan residues in proteins

Abstract

AbstractThe influence of environmental hydrophobicity on the UV resonance Raman spectra of tryptophan residues in proteins was studied using laser excitation at 230 nm. An increase in hydrophobicity was found to enhance the resonance Raman cross‐sections without significant changes in the frequencies and relative intensities of the Trp vibrational modes. It was shown that this effect is strong enough to be used for studies of the tryptophanyl micro‐environment in proteins. The resonance Raman cross‐section of tryptophanyl increases relative to that of N‐Ac‐Trpethyl ester by factors of 2, 3, 3, 4.4 and 1.6 for melittin, melittin incorporated into liposomes, azurin, bacteriorhodopsin and lysozyme, respectively.