Abstract
Transhydrogenase couples the redox reaction between NAD(H) and NADP(H) to proton translocation across a membrane. In membrane vesicles from Escherichia coli and Rhodospirillum rubrum, the transhydrogenase reaction (measured in the direction driving inward proton translocation) was inhibited by Zn(2+) and Cd(2+). However, depending on pH, the metal ions either had no effect on, or stimulated, "cyclic" transhydrogenation. They must, therefore, interfere specifically with steps involving binding/release of NADP(+)/NADPH: the steps thought to be associated with proton translocation. It is suggested that Zn(2+) and Cd(2+) bind in the proton-transfer pathway and block inter-conversion of states responsible for changing NADP(+)/NADPH binding energy.
Original language | English |
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Pages (from-to) | 2863-2867 |
Number of pages | 5 |
Journal | FEBS Letters |
Volume | 579 |
Issue number | 13 |
DOIs | |
Publication status | Published - 23 May 2005 |
Keywords
- membrane proteins
- zinc ions
- hydride transfer
- nicotinamide nucleotides
- proton translocation
- transhydrogenase