title: Properties of copper-free pig kidney amine oxidase: role of topa quinone.
abstract: Copper removal from pig kidney amine oxidase containing Cu/topaquinone (TPQ) has been obtained using CN(-) in the presence of the poor substrate p-(dimethylamino)benzylamine. Upon removal of copper, the enzyme loses its activity while the TPQ cofactor remains in its oxidized form. The addition of copper to the apo-form fully restores the active enzyme. The CN(-) treatment in the presence of sodium dithionite or good substrates (cadaverine or benzylamine) also removes copper but the TPQ cofactor is irreversibly reduced and the addition of copper does not regenerate the active enzyme. Ni(II) and Zn(II) do not bind the apo-protein in contrast to Co(II) which is incorporated to the same extent as Cu(II). However, Co-reconstituted enzyme only shows a very low activity. These results demonstrate that copper is essential for the catalytic mechanism because it maintains the correct active site geometry.
authors.affiliation: Department of Applied Sciences in Biosystems, University of Cagliari, Cagliari, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Mura
authors.forename: Alessandra
authors.initials: A
authors.lastname: Padiglia
authors.forename: Rosaria
authors.initials: R
authors.lastname: Medda
authors.forename: Francesca
authors.initials: F
authors.lastname: Pintus
authors.forename: Alessandro
authors.initials: A
authors.lastname: Finazzi Agrò
authors.forename: Giovanni
authors.initials: G
authors.lastname: Floris
mesh_terms: D006631:Amine Oxidase (Copper-Containing) / Q000737:chemistry* / Q000378:metabolism; D000814:Aniline Compounds / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D001051:Apoenzymes / Q000737:chemistry / Q000378:metabolism; D001596:Benzylamines / Q000737:chemistry / Q000378:metabolism; D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D004295:Dihydroxyphenylalanine / Q000031:analogs & derivatives* / Q000737:chemistry; D007668:Kidney / Q000201:enzymology*; D007700:Kinetics; D013552:Swine
chemical_list: D000814:Aniline Compounds; D001051:Apoenzymes; D001596:Benzylamines; C035815:4-dimethylaminobenzylamine; D004295:Dihydroxyphenylalanine; C067626:6-hydroxydopa quinone; D003300:Copper; D006631:Amine Oxidase (Copper-Containing)