title: Structural properties of human monoamine oxidases A and B.
abstract: The structural elucidations of human monoamine oxidases A and B (MAO-A and -B) have provided novel insights into their similarities and differences. Although the enzymes exhibit ∼70% sequence identities, highly conserved chain folds, and are structurally identical in their flavin adenine dinucleotide (FAD)-binding sites, they differ considerably in the structures of their active sites opposite the flavin cofactor. MAO-A has a monopartite cavity of ∼550 Å³, and MAO-B exhibits a bipartite cavity structure with an entrance cavity of 290 Å³ and a substrate cavity of ∼400 Å³. Ile199 functions as a conformational "gate" separating the two cavities. Both enzymes are anchored to the outer mitochondrial membrane via C-terminal helical tails. Loop structures are found at the entrances to their active sites at the membrane surface. Although the crystal structure of human MAO-A is monomeric while MAO-B is dimeric, both enzymes are dimeric in their membrane-bound forms. Dimerization may be important for the favorable orientation of the resultant protein dipole moment toward the anionic membrane surface.
authors.affiliation: Department of Genetics and Microbiology, University of Pavia, Pavia, Italy.
authors.forename: Claudia
authors.initials: C
authors.lastname: Binda
authors.forename: Andrea
authors.initials: A
authors.lastname: Mattevi
authors.forename: Dale E
authors.initials: DE
authors.lastname: Edmondson
mesh_terms: D000818:Animals; D018360:Crystallography, X-Ray; D006801:Humans; D007527:Isoenzymes / Q000737:chemistry / Q000378:metabolism / Q000502:physiology; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology; D008995:Monoamine Oxidase / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology; D055503:Protein Multimerization; D051381:Rats; D013329:Structure-Activity Relationship
chemical_list: D007527:Isoenzymes; D008565:Membrane Proteins; D008995:Monoamine Oxidase