CRYSTAL STRUCTURE OF A BACTERIAL COPPER-CONTAINING AMINE OXIDASE FROM ARTHROBACTER GLOBOFORMIS AT 2.8Å RESOLUTION. Matthew C.J. Wilce, Hans C. Freeman, J. Mitchell Guss, Vinay Kumar (University of Sydney, NSW 2006, Australia) and William S. McIntire, (Department of Veterans Affairs Medical Center, San Francisco, CA 94143, USA)

We present the crystal structure and structural analysis of a bacterial copper-containing amine oxidase (AO). AOs are homodimeric proteins with molecular weights of between 70-90 kDa per subunit. Their function is the oxidative metabolism of amines in the presence of molecular dioxygen. They are involved in many fundamental cellular processes including: tissue differentiation, tissue development, wound healing, cancer and possibly programmed cell death. AOs are of particular importance in gram-positive methylotrophs, including Arthrobacter spp., as these organisms are able to utilise methylamine as their sole carbon and energy source.

A. globoformis AO crystallises in a number of forms with and without the presence of ammonium salts that are known to inactivate the enzyme. The structure of the crystal form known as type II is reported here. The crystals were grown from LiSO₄. The space group is C2 (a=157.6, b=64.3, c=92.6 Å, (=112.6() with one subunit per asymmetric unit. Molecular replacement was used to determine an initial phase set. Both the pea seedling and E. coli AO [Parsons, M.R. et al. (1995). Structure, 3, 1171-1184] structures were successfully used as search models. The structure has been refined at 2.8Å resolution. The structure of A. globoformis AO is compared with both the E. coli AO and pea seedling AO structures with particular reference to the active site.