04 March 1994
Vol 263, Issue 5151

About The Cover

Model of the enzyme acetylcholinesterase with electrostatic lines of force (yellow) emanating from the interior of the active site (buried). The field lines exit mostly through the main entrance (blue atoms) or through a channel (``back door'') to the active site. A molecular dynamics simulation shows transient opening of this back door (top), which may facilitate the entry or exit of substrate, products, or solvent. See page 1276. [Graphics: Michael K. Gilson, using Insight II software (Biosym)]