title: Unusual pKa of the carboxylate at the putative catalytic position of the thermophilic F1-ATPase beta subunit determined by 13C-NMR.
abstract: Glutamic acid-190 in the beta subunit of F1-ATPase from thermophilic Bacillus PS-3 (TF1) was reported to be essential for the ATPase activity. The mutant TF1beta subunit in which Glu-190 had been substituted by cysteine was carboxymethylated with 13C-labeled monoiodoacetic acid. The pKa value of the carboxymethylene group at the 190 position was determined as 5.6 +/- 0.4 by 13C-NMR. On the basis of this value, the pKa of the carboxylate of Glu-190 of the TF1beta subunit was estimated to be 6.8 +/- 0.5. The unusually high pKa could play a role in the catalytic mechanism of F1-ATPase.
authors.affiliation: Department of Bioengineering, Faculty of Engineering, Yokohama National University, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Tozawa
authors.forename: H
authors.initials: H
authors.lastname: Ohbuchi
authors.forename: H
authors.initials: H
authors.lastname: Yagi
authors.forename: T
authors.initials: T
authors.lastname: Amano
authors.forename: T
authors.initials: T
authors.lastname: Matsui
authors.forename: M
authors.initials: M
authors.lastname: Yoshida
authors.forename: H
authors.initials: H
authors.lastname: Akutsu
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D001407:Bacillus / Q000201:enzymology; D001665:Binding Sites; D002233:Carbocysteine / Q000737:chemistry / Q000378:metabolism; D002264:Carboxylic Acids / Q000737:chemistry / Q000378:metabolism; D002384:Catalysis; D018698:Glutamic Acid / Q000737:chemistry / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007461:Iodoacetates; D019807:Iodoacetic Acid; D009682:Magnetic Resonance Spectroscopy; D009154:Mutation; D006180:Proton-Translocating ATPases / Q000737:chemistry / Q000378:metabolism*; D013696:Temperature
chemical_list: D002264:Carboxylic Acids; D007461:Iodoacetates; D018698:Glutamic Acid; D000244:Adenosine Diphosphate; D002233:Carbocysteine; D006180:Proton-Translocating ATPases; D019807:Iodoacetic Acid