Scientists Huan-Xiang Zhou, Stanislaw Wlodek, and Andrew McCammon created this animation showing "the 'breathing' motions of the gorge or channel that leads from the region outside the enzyme Acetylcholinesterase (AChE), to the active site." The enzyme AChE controls the communication among nerve and muscle cells. This animation demonstrates, for the first time, the role of molecular dynamics in enzyme specificity. It is based on "a combination of computational models and theoretical calculations," which were published in the August 4, 1998 issue of the Proceedings of the National Academy of Sciences.