title: X-ray absorption analysis of the active site of Streptomyces antibioticus Tyrosinase upon binding of transition state analogue inhibitors.
abstract: The key structural features that define the reaction mechanism of the binuclear copper enzyme Tyrosinase (Ty) from Streptomyces antibioticus were investigated by X-ray absorption spectroscopy. The data for the met form, the halide bound derivative and the adduct with the competitive inhibitor and transition state analogue Kojic acid were analysed using the recently developed MXAN package. This analysis permitted the definition of structural clusters that include all atoms within 5A from the metal ions of the active site. The data obtained for the different forms provide validation of the structural models previously proposed on the basis of the magnetic properties investigated by both pulsed EPR and paramagnetic NMR spectroscopies. The structural model of the reaction center obtained in this solution study is compared with the crystallographic structures recently proposed for several derivatives of bacterial Ty to suggest that only one of these structures is relevant to solution conditions.
authors: Department of Biology, University of Padova, Via Ugo Bassi 58B, 35121, Padova, Italy. luigi.bubacco@unipd.it
authors: Luigi
authors: L
authors: Bubacco
authors: Roberto
authors: R
authors: Spinazze
authors: Stefano
authors: S
authors: della Longa
authors: Maurizio
authors: M
authors: Benfatto
mesh_terms: D015502:Absorptiometry, Photon; D001665:Binding Sites; D003198:Computer Simulation; D004789:Enzyme Activation; D008956:Models, Chemical; D008958:Models, Molecular; D014442:Monophenol Monooxygenase / Q000737:chemistry* / Q000648:ultrastructure*; D010455:Peptides / Q000737:chemistry*; D044367:Phase Transition; D011485:Protein Binding; D013303:Streptomyces antibioticus / Q000201:enzymology*
chemical_list: D010455:Peptides; D014442:Monophenol Monooxygenase