The study of a protein's structure is a powerful way to learn more about its function. Often, however, such structural studies can provide only a single snapshot in space and time. Yet proteins and other macromolecules are dynamic, fluid structures, and the motions that occur within them are key to many of the processes in which they are involved.

To facilitate the study of such motions, Mark Gerstein and colleagues at Yale University have created the Database of macromolecular movements. Their aim, they say, is to “survey all the known instances of domain movements in proteins and other molecules for which there is experimental evidence for the movement”.

The database is first divided into broad sections — motions in domains, for example, or in fragments smaller or larger than domains. Within each section, molecules are then classified according to the various low-energy conformational changes that are known to occur. The result is a logically organized, albeit rather list-like, collection of information.

But the site is much more than simply a database. The motions analysis includes a gallery of movies, where proteins come to life in two dimensions. Each can be viewed in various representations (ribbon, CA trace, ball-and-stick or hinge), with three-dimensional movies also available for some proteins. There is also a 'MorphServer', which allows users to produce two- and three-dimensional animations of the pathway between two protein subunit conformations.

Other features include free software for studying macromolecular geometry, allowing volumes, surfaces, axes, angles and distances to be calculated, and a useful page of links related to protein motions.