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Unusual p K a of the carboxylate at the putative catalytic position of the thermophilic F 1 ‐ATPase β subunit determined by 13 C‐NMR
Author(s) -
Tozawa Kaeko,
Ohbuchi Hiroshi,
Yagi Hiromasa,
Amano Toyoki,
Matsui Tadashi,
Yoshida Masasuke,
Akutsu Hideo
Publication year - 1996
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(96)01155-6
Subject(s) - thermophile , cysteine , protein subunit , chemistry , carboxylate , stereochemistry , atpase , glutamic acid , mutant , enzyme , biochemistry , amino acid , gene
Glutamic acid‐190 in the β subunit of F 1 ‐ATPase from thermophilic Bacillus PS‐3 (TF 1 ) was reporte to be essential for the ATPase activity. The mutant TF 1 β subunit in which Glu‐190 had been substituted by cysteine was carboxymethylated with 13 C‐labeled monoiodoacetic acid. The p K a value of the carboxymethylene group at the 190 position was determined as 5.6 ± 0.4 by 13 C‐NMR. On the basis of this value, the p K a of the carboxylate of Glu‐190 of the TF 1 β subunit was estimated to be 6.8 ± 0.5. The unusually high p K a could play a role in the catalytic mechanism of F 1 ‐ATPase.