title: ATR-FTIR study of the protonation states of the Glu residue in the multicopper oxidases, CueO and bilirubin oxidase.
abstract: Redox-induced protonation state changes of the Glu residue in the multicopper oxidases, CueO and bilirubin oxidase (BO), were studied by attenuated total reflectance-Fourier transform infrared spectroscopy. By monitoring IR bands of the carboxylic acid C=O stretch in the wild-type and Glu-to-Gln mutant enzymes the Glu506 of CueO (Glu463 of BO) was found to be unprotonated in the oxidised and protonated in the reduced forms. The results provided direct evidence for proton uptake by the Glu, suggesting it plays a key role in the proton donation to the activated oxygen species in the catalytic cycle.
authors: Frontier Research Center, Toyota Central R&D Laboratories Inc., Nagakute, Aichi, Japan. miwaki@mosk.tytlabs.co.jp
authors: Masayo
authors: M
authors: Iwaki
authors: Kunishige
authors: K
authors: Kataoka
authors: Tsutomu
authors: T
authors: Kajino
authors: Ryosuke
authors: R
authors: Sugiyama
authors: Hirotoshi
authors: H
authors: Morishita
authors: Takeshi
authors: T
authors: Sakurai
mesh_terms: D029968:Escherichia coli Proteins / Q000737:chemistry*; D018698:Glutamic Acid / Q000737:chemistry* / Q000235:genetics; D005973:Glutamine / Q000737:chemistry / Q000235:genetics; D009154:Mutation; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry*; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000737:chemistry* / Q000235:genetics; D011522:Protons; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D029968:Escherichia coli Proteins; D011522:Protons; D005973:Glutamine; D018698:Glutamic Acid; D010088:Oxidoreductases; C499679:cueO protein, E coli; D044925:Oxidoreductases Acting on CH-CH Group Donors; C042401:bilirubin oxidase