title: An EPR, thermostability and pH-dependence study of wild-type and mutant forms of catechol 1,2-dioxygenase from Acinetobacter radioresistens S13.
abstract: Intradiol dioxygenase are iron-containing enzymes involved in the bacterial degradation of natural and xenobiotic aromatic compounds. The wild-type and mutants forms of catechol 1,2-dioxygenase Iso B from Acinetobacter radioresistens LMG S13 have been investigated in order to get an insight on the structure-function relationships within this system. 4K CW-EPR spectroscopy highlighted different oxygen binding properties of some mutants with respect to the wild-type enzyme, suggesting that a fine tuning of the substrate-binding determinants in the active site pocket may indirectly result in variations of the iron reactivity. A thermostability investigation by optical spectroscopy, that reports on the state of the metal center, showed that the structural stability is more influenced by the type rather than by the position of the mutation. Finally, the influence of pH and temperature on the catalytic activity was monitored and discussed in terms of perturbations induced on the tertiary contact network of the enzyme.
authors.affiliation: Dipartimento di Scienze della Vita e Biologia dei Sistemi, Università di Torino, Via Accademia Albertina 13, 10123, Turin, Italy.
authors.forename: Raffaella
authors.initials: R
authors.lastname: Caglio
authors.forename: Enrica
authors.initials: E
authors.lastname: Pessione
authors.forename: Francesca
authors.initials: F
authors.lastname: Valetti
authors.forename: Carlo
authors.initials: C
authors.lastname: Giunta
authors.forename: Elena
authors.initials: E
authors.lastname: Ghibaudi
mesh_terms: D000150:Acinetobacter / Q000201:enzymology*; D019943:Amino Acid Substitution; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D050548:Catechol 1,2-Dioxygenase / Q000737:chemistry* / Q000235:genetics; D004578:Electron Spin Resonance Spectroscopy; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D016297:Mutagenesis, Site-Directed; D010100:Oxygen / Q000737:chemistry; D012996:Solutions; D044366:Transition Temperature
chemical_list: D001426:Bacterial Proteins; D012996:Solutions; D050548:Catechol 1,2-Dioxygenase; D010100:Oxygen