NMR studies of mobility within protein structure

NMR studies of dynamics within structure have revealed that a quite new approach to protein structure and its relation to function is necessary. This approach requires the consideration in detail of the following: Local movements of groups and small segments to allow fast recognition and fitting. The motion concerns on/off rates as well as binding. The observations affect surface/surface recognition, e.g. of antigen/antibody as well as of substrate and protein. Somewhat larger interdomain or N‐ and C‐terminal segments which allow rearrangement. Cases in point are the movement of segments in blood‐clotting proteins or in histones. Relative motion of helices in hinges. These actions are likely in such enzymes as kinases and P‐450 cytochromes. Relative motion of helices within domains (relative to other helices or sheets) in mechanical devices (triggers) e.g. in calmodulin. General motion in random proteins. Examples extend from rubber‐like proteins (entropy sensors), some glycoproteins, to proteins carrying peptide hormones to be generated only after hydrolysis. Order → disorder transitions locally as in osteocalcin and metallothionine. Swinging arm motions associated with special s