One pair of electrons is divided so that:
- one transfer proceeds favorably
- the released free energy drives a second, unfavorable reduction
Operational definition
Redox-coupling mechanism.
The coupling of two electron-transfer reactions by splitting a pair of electrons from one donor toward two acceptors with different reduction potentials.
One branch is thermodynamically favorable and supplies the energetic drive for the other, unfavorable branch. The process permits the generation of strongly reducing electron carriers without direct expenditure of ATP or a preexisting ion gradient.