Conformation and Dynamics of Nucleic Acids and Proteins from Laser Raman Spectroscopy

Abstract

Nucleic acids and proteins may be studied with both classical or resonance Raman spectroscopies. In the former a visible laser line is selected, commonly one of the argon lines at 514.5 nm or 488.0 nm. One sees in these spectra Raman bands which are due to the vibrations of the backbone of the biological micromolecules as well as the side chains. Much information can be obtained on the average conformation of these biological macromolecules from analysis of the vibrational frequencies arising from the backbone portion of the chain. This is because the frequencies from the backbone are closely related to the torsional angles in which the principle chain or backbone of the biological polymer exist. On the other hand, with resonance Raman spectroscopy one can study individual side chains such as tyrosine or tryptophane. One can also design chromophoric substrates to make enzyme substrate complexes and study the conformation or the structure of the chromophore at the change in the enzymatic catalytic event. Examples of all of these types of spectroscopies and conformational information both static and dynamic which can be obtained will be discussed below. Suffice it to say however, that at the present time classical and resonance Raman spectroscopy presents powerful techniques for the study of the conformation of biological macromolecules both in vivo and vitro.