Abstract
The proton translocating ATP-synthase from chloroplasts, CF0F1, was isolated and reconstituted into asolectin liposomes. [γ-32P]ATP hydrolysis was measured under uni-site conditions. When 1 mM unlabeled ATP was added so that all ATP-binding sites were occupied, [γ-32P]ATP bound to the first site, was hydrolyzed with a rate of 0.5 ATP/(CF0F1 s). In a second experiment, first cold ATP was hydrolyzed under uni-site conditions and then 1 mM [γ-32P]ATP was added. This allows under otherwise identical conditions the measurement of the rate of ATP hydrolysis catalyzed by the second (and possibly third) site. It resulted in a rate of 80 ATP/(CF0F1 s). It is concluded that the catalytic nucleotide binding sites are heterogeneous: there exists one nucleotide binding site which hydrolyzes ATP with a maximal turnover of 0.5/s and another one (or two) which hydrolyze ATP with a turnover of 80/s. The latter one is the catalytic site for maximal turnover.
Original language | English (US) |
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Pages (from-to) | 33-36 |
Number of pages | 4 |
Journal | FEBS Letters |
Volume | 259 |
Issue number | 1 |
DOIs | |
State | Published - Dec 18 1989 |
Externally published | Yes |
Keywords
- ATPase, H-
- CFF
- Chloroplast
- Nucleotide binding site
- Reconstitution
- Uni-site catalysis
ASJC Scopus subject areas
- Biophysics
- Structural Biology
- Biochemistry
- Molecular Biology
- Genetics
- Cell Biology