title: Structure and mechanism leading to formation of the cysteine sulfinate product complex of a biomimetic cysteine dioxygenase model.
abstract: Cysteine dioxygenase is a unique nonheme iron enzyme that is involved in the metabolism of cysteine in the body. It contains an iron active site with an unusual 3-His ligation to the protein, which contrasts with the structural features of common nonheme iron dioxygenases. Recently, some of us reported a truly biomimetic model for this enzyme, namely a trispyrazolylborato iron(II) cysteinato complex, which not only has a structure very similar to the enzyme-substrate complex but also represents a functional model: Treatment of the model with dioxygen leads to cysteine dioxygenation, as shown by isolating the cysteine part of the product in the course of the work-up. However, little is known on the conversion mechanism and, so far, not even the structure of the actual product complex had been characterised, which is also unknown in case of the enzyme. In a multidisciplinary approach including density functional theory calculations and X-ray absorption spectroscopy, we have now determined the structure of the actual sulfinato complex for the first time. The Cys-SO2 (-) functional group was found to be bound in an η(2) -O,O-coordination mode, which, based on the excellent resemblance between model and enzyme, also provides the first support for a corresponding binding mode within the enzymatic product complex. Indeed, this is again confirmed by theory, which had predicted a η(2) -O,O-binding mode for synthetic as well as the natural enzyme.
authors.affiliation: Humboldt-Universität zu Berlin, Institut für Chemie, Brook-Taylor-Strasse 2, 12489 Berlin (Germany), Fax: (+49) 30-2093-6966.
authors.forename: Madleen
authors.initials: M
authors.lastname: Sallmann
authors.forename: Suresh
authors.initials: S
authors.lastname: Kumar
authors.forename: Petko
authors.initials: P
authors.lastname: Chernev
authors.forename: Joscha
authors.initials: J
authors.lastname: Nehrkorn
authors.forename: Alexander
authors.initials: A
authors.lastname: Schnegg
authors.forename: Devesh
authors.initials: D
authors.lastname: Kumar
authors.forename: Holger
authors.initials: H
authors.lastname: Dau
authors.forename: Christian
authors.initials: C
authors.lastname: Limberg
authors.forename: Sam P
authors.initials: SP
authors.lastname: de Visser
mesh_terms: D032701:Biomimetics; D002384:Catalysis; D018360:Crystallography, X-Ray; D003545:Cysteine / Q000031:analogs & derivatives* / Q000737:chemistry; D050558:Cysteine Dioxygenase / Q000737:chemistry* / Q000378:metabolism; D005296:Ferrous Compounds / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D008958:Models, Molecular; D056928:X-Ray Absorption Spectroscopy
chemical_list: D005296:Ferrous Compounds; D007501:Iron; D050558:Cysteine Dioxygenase; D003545:Cysteine; C013461:cysteine sulfinic acid
keywords: density functional calculations; enzyme catalysis; enzyme models; oxygenation; reaction mechanisms