title: Roles of Trp144 and Tyr203 in copper-containing nitrite reductase from Achromobacter cycloclastes IAM1013.
abstract: The roles of the Trp144 and Tyr203 residues near the type 1 Cu site of Achromobacter cycloclastes nitrite reductase (AcNIR) have been examined with mutants of AcNIR. Tyr203 is located on the protein surface near the type 1 Cu site of AcNIR, and Trp144 is between the Tyr203 and the type 1 Cu center in AcNIR. Single mutation of Trp144 or Tyr203 in AcNIR to Leu resulted in decreased rate constants of intermolecular electron transfer from its cognate pseudoazurin (AcPAZ) (k(ET)=1.9x10(5), 2.2x10(5), and 7.3x10(5)M(-1)s(-1) for W144L, Y203L, and wild-type AcNIR, respectively). The intermolecular electron transfer rate constant of double mutant AcNIR (W144L/Y203L) was the same as those of single mutants (k(ET)=1.9x10(5)M(-1)s(-1) for W144L/Y203L). The redox potentials, coordination structures of the type 1 Cu, and the enzyme activities of AcNIR were affected little by the mutation.
authors.affiliation: Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Yamaguchi
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Shuta
authors.forename: Shinnichiro
authors.initials: S
authors.lastname: Suzuki
mesh_terms: D042422:Achromobacter cycloclastes / Q000201:enzymology*; D003300:Copper / Q000378:metabolism*; D004563:Electrochemistry; D004579:Electron Transport; D007700:Kinetics; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D050901:Nitrate Reductase; D009565:Nitrate Reductases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011487:Protein Conformation; D014364:Tryptophan / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism*
chemical_list: D014443:Tyrosine; D003300:Copper; D014364:Tryptophan; D009565:Nitrate Reductases; D050901:Nitrate Reductase