Conformational changes in biological macromolecules

Some known conformational changes occurring in proteins and peptides are summarized and discussed. A novel nonradiative energy transfer technique, enabling evaluation of the conformation and intramolecular motility of polypeptides in solution, is described. The method should prove useful in the elucidation of the conformational motility prevailing in various biopolymers. The following three possible levels of flexibility in proteins are described: a. flexibility of chain segments; b. domain flexibility; and c. motion of side chains. Evidence is forwarded to show that these conformational motions actually occur in some proteins, as revealed by a number of physical chemical techniques. The possible biological significance of the predicted conformational flexibility and conformational fluctuations of biopolymers is finally discussed.