title: Structure and reaction mechanism in the heme dioxygenases.
abstract: As members of the family of heme-dependent enzymes, the heme dioxygenases are differentiated by virtue of their ability to catalyze the oxidation of l-tryptophan to N-formylkynurenine, the first and rate-limiting step in tryptophan catabolism. In the past several years, there have been a number of important developments that have meant that established proposals for the reaction mechanism in the heme dioxygenases have required reassessment. This focused review presents a summary of these recent advances, written from a structural and mechanistic perspective. It attempts to present answers to some of the long-standing questions, to highlight as yet unresolved issues, and to explore the similarities and differences of other well-known catalytic heme enzymes such as the cytochromes P450, NO synthase, and peroxidases.
authors.affiliation: Department of Chemistry, George Porter Building, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom.
authors.forename: Igor
authors.initials: I
authors.lastname: Efimov
authors.forename: Jaswir
authors.initials: J
authors.lastname: Basran
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Thackray
authors.forename: Sandeep
authors.initials: S
authors.lastname: Handa
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Mowat
authors.forename: Emma Lloyd
authors.initials: EL
authors.lastname: Raven
mesh_terms: D000818:Animals; D055162:Biocatalysis; D006801:Humans; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase / Q000737:chemistry / Q000378:metabolism*; D007737:Kynurenine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D015394:Molecular Structure; D017434:Protein Structure, Tertiary; D014364:Tryptophan / Q000737:chemistry / Q000378:metabolism*; D014366:Tryptophan Oxygenase / Q000737:chemistry / Q000378:metabolism*
chemical_list: D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase; C007772:N'-formylkynurenine; D007737:Kynurenine; D014364:Tryptophan; D014366:Tryptophan Oxygenase