title: Met144Ala mutation of the copper-containing nitrite reductase from Alcaligenes xylosoxidans reverses the intramolecular electron transfer.
abstract: Pulse radiolysis has been employed to investigate the intramolecular electron transfer (ET) between the type 1 (T1) and type 2 (T2) copper sites in the Met144Ala Alcaligenes xylosoxidans nitrite reductase (AxCuNiR) mutant. This mutation increases the reduction potential of the T1 copper center. Kinetic results suggest that the change in driving force has a dramatic influence on the reactivity: The T2Cu(II) is initially reduced followed by ET to T1Cu(II). The activation parameters have been determined and are compared with those of the wild-type (WT) AxCuNiR. The reorganization energy of the T2 site in the latter enzyme was calculated to be 1.6+/-0.2 eV which is two-fold larger than that of the T1 copper center in the WT protein.
authors.affiliation: Institute of Analytical Chemistry, The Danish University of Pharmaceutical Sciences, 2100 Copenhagen, Denmark. of@dfuni.dk
authors.forename: Ole
authors.initials: O
authors.lastname: Farver
authors.forename: Robert R
authors.initials: RR
authors.lastname: Eady
authors.forename: Gary
authors.initials: G
authors.lastname: Sawers
authors.forename: Miguel
authors.initials: M
authors.lastname: Prudêncio
authors.forename: Israel
authors.initials: I
authors.lastname: Pecht
mesh_terms: D000421:Alcaligenes / Q000201:enzymology*; D019943:Amino Acid Substitution; D001665:Binding Sites; D004579:Electron Transport; D007700:Kinetics; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D009572:Nitrite Reductases / Q000235:genetics* / Q000378:metabolism*; D010084:Oxidation-Reduction; D011675:Pulse Radiolysis
chemical_list: D009572:Nitrite Reductases; C052695:nitrite reductase, copper-containing