NOVEL VIBRATIONAL ASSIGNMENTS FOR PROTEINS FROM RAMAN-SPECTRA OF VIRUSES

Raman spectroscopy and ultraviolet resonance Raman spectroscopy are ve rsatile methods for probing details of protein structure and dynamics in complex biological assemblies, including viruses. The information c ontained in the Raman spectrum of a virus is ordinarily interpreted on the basis of an understanding that has been developed from detailed s pectroscopic investigations of simpler and better characterized molecu lar structures, such as small globular proteins, peptides and related model compounds and their isotopic derivatives. The model systems appr oach serves generally as the foundation for reliable band assignments and has been the key to successful application of Raman methods to sup ramolecular assemblies. However, the converse approach is also possibl e. The supramolecular assembly may serve as a 'model compound' and its Raman signature may provide novel spectra-structure correlations appl icable to isolated protein subunits, simpler proteins or related small molecules. Thus, the Raman spectrum of a virus particle can yield new insights into protein vibrational assignments. Here, a number of new vibrational assignments that have emerged from Raman studies of filame ntous viruses are identified. The Raman bands in question have not bee n identified previously in proteins and are demonstrated to originate either from vibrations of the protein main-chain (C alpha H marker, 13 40-1350 cm(-1)) or from aromatic amino acid side chains (phenylalanine marker, 827 cm(-1); tyrosine singlet, 850-855 cm(-1); tryptophan mark er, 1560 cm(-1)). The present results, which are considered in the lig ht of existing correlations between data on Raman spectra and protein structure, suggest that much remains to be learned about the structura l significance of protein Raman bands. (C) 1998 John Wiley & Sons, Ltd .