ATR-FTIR study of the protonation states of the Glu residue in the multicopper oxidases, CueO and bilirubin oxidase.
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.
Iwaki
Masayo
M
Frontier Research Center, Toyota Central R&D Laboratories Inc., Nagakute, Aichi, Japan. miwaki@mosk.tytlabs.co.jp
Kataoka
Kunishige
K
Kajino
Tsutomu
T
Sugiyama
Ryosuke
R
Morishita
Hirotoshi
H
Sakurai
Takeshi
T
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
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