Jaws. A film of enzyme dynamics

Offprint requests to. C. Sander dominate atomic displacements and that surprisingly few of these suffice to describe experimentally determined fluctuations of atomic position. We have now calculated the normal mode dynamics of the enzymes lysozyme and ribonuclease [2]. A film of their lowest frequency normal modes shows opening and closing of the active site cleft. This jawlike behaviour is due to the collective motion of entire protein domains and is likely to facilitate catalysis. We are led to the suggestion that optimization of enzyme function in natural evolution or genetic engineering must affect not only the nature and positioning of active site residues but also the nature and positioning of key residues modulating domain dynamics.