STRUCTURAL ASPECTS OF SERPIN INHIBITION

The essential roles of proteins of the serpin family in many physiolog ical processes, along with new discoveries of their unique folding pro perties, have attracted intense interest in recent years. Many serpins display unusual mobile behavior attributed to rearrangements of alpha -helical or beta-sheet domains, whereby large scale transitions accomp any a Variety of functions, including inactivation. This unusual behav ior was first recognized with the X-ray structure of modified al-prote inase inhibitor. Subsequent experiments, including new X-ray structure s, have revealed a surprising Variety of conformations which are funct ionally important but only partially understood. We review here experi mental evidence for conformations relevant to the serpin inhibitory me chanism.