Secondary Considerations
John T. Pelton
Spectroscopic methods for the determination of protein secondary structure are reviewed. Circular dichroism (CD) provides a rapid means of examining protein secondary structure in dilute solutions and can also be used to monitor conformational changes as a function of environmental change or the addition of a ligand. The stretching vibrations of the amide carbonyl atoms are analyzed by infrared (IR) and Raman spectroscopies to determine the distribution of secondary structures in proteins. In contrast to CD spectroscopy, IR and Raman spectroscopy can be used to study proteins in solids, powders, crystals, and lipid membranes as well as in solutions. NMR chemical shifts have been used to determine protein secondary structure and provide information on the positions of these elements within the primary sequence of a protein. A few examples are provided to illustrate the power of these techniques, and the use of protein secondary structure to assign biological function of proteins is discussed.
