title: It can be a complicated life being an enzyme.
abstract: It is becoming increasingly apparent that many well-known enzymes have alternative non-enzymic functions. Similarly, several proteins that were identified as having non-catalytic functions were subsequently found to have enzyme activities. Some examples are considered to illustrate the diversity of alternative functions. The semicarbazide-sensitive amine oxidase (EC 1.4.3.6) is considered in more depth as an example. It was originally believed to be a detoxifying enzyme, but the reaction products may have important signalling functions. Furthermore, this enzyme, from some sources, also behaves as a vascular-adhesion protein. Finally, the challenges posed by such multiplicity of functions for the interpretation of genetic deletion, in vivo inhibition and the development of functional protein databases are briefly considered.
authors.affiliation: Department of Biochemistry, Trinity College, Dublin 2, Ireland. ktipton@tcd.ie
authors.forename: K F
authors.initials: KF
authors.lastname: Tipton
authors.forename: M I
authors.initials: MI
authors.lastname: O'Sullivan
authors.forename: G P
authors.initials: GP
authors.lastname: Davey
authors.forename: J
authors.initials: J
authors.lastname: O'Sullivan
mesh_terms: D006631:Amine Oxidase (Copper-Containing) / Q000378:metabolism*; D002384:Catalysis; D002477:Cells / Q000201:enzymology*; D004798:Enzymes / Q000145:classification / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008954:Models, Biological
chemical_list: D004798:Enzymes; D006631:Amine Oxidase (Copper-Containing)