The catalytic properties of enzymes, containing the Asp-His-Ser triads are deeply investigated for a long time. Serine endopeptidases, cutinases, acetylcholinesterases, cellulases, among other enzymes, contain these triads. We found that solely the geometric properties of just four points in the spatial structure of these enzymes are characteristic to their family (Fig. 3). (C) 2009 Elsevier Inc. All rights reserved