Bioinformatics (27 September 2005) SUMMARY: MACiE (Mechanism, Annotation and Classification in Enzymes) is a publicly available web-based database, held in CMLReact (an XML application), that aims to help our understanding of the evolution of enzyme catalytic mechanisms and also to create a classification system which reflects the actual chemical mechanism (catalytic steps) of an enzyme reaction, not only the overall reaction. AVAILABILITY: http://www-mitchell.ch.cam.ac.uk/macie.... Gemma L Holliday, Gail J Bartlett, Daniel E Almonacid, Noel M O'boyle, Peter Murray-Rust, Janet M Thornton, John B O Mitchell - Egon Willighagen