title: EXAFS reveals a structural zinc binding site in the bovine NADH-Q oxidoreductase.
abstract: The metal content of bovine NADH-Q oxidoreductase determined by inductively-coupled plasma atomic-emission spectroscopy reveals the presence of about one atom of zinc per molecule of flavin mononucleotide. We applied Zn K-edge extended X-ray absorption fine structure spectroscopy (EXAFS) to investigate the local structure of the bound zinc ion and to identify the nature of the coordinating residues. The EXAFS spectrum is consistent with a structured zinc binding site. By combining information from first-shell analysis and from metalloprotein data bases putative binding clusters have been built and fitted to the experimental spectrum using ab initio simulations. The best fitting binding cluster is formed by two histidine and two cysteine residues arranged in a tetrahedral geometry.
authors.affiliation: Department of Biology, University of Bologna, Via Irnerio n 42, 40126, Bologna, Italy.
authors.forename: Lisa
authors.initials: L
authors.lastname: Giachini
authors.forename: Francesco
authors.initials: F
authors.lastname: Francia
authors.forename: Federico
authors.initials: F
authors.lastname: Boscherini
authors.forename: Consiglia
authors.initials: C
authors.lastname: Pacelli
authors.forename: Tiziana
authors.initials: T
authors.lastname: Cocco
authors.forename: Sergio
authors.initials: S
authors.lastname: Papa
authors.forename: Giovanni
authors.initials: G
authors.lastname: Venturoli
mesh_terms: D000818:Animals; D001665:Binding Sites; D002417:Cattle; D003545:Cysteine / Q000737:chemistry / Q000378:metabolism; D006639:Histidine / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D011808:Quinone Reductases / Q000737:chemistry* / Q000378:metabolism; D013053:Spectrophotometry; D013057:Spectrum Analysis; D013329:Structure-Activity Relationship; D014965:X-Rays; D015032:Zinc / Q000737:chemistry* / Q000378:metabolism
chemical_list: D006639:Histidine; C041831:NADH dehydrogenase (quinone); D011808:Quinone Reductases; D015032:Zinc; D003545:Cysteine