Coupling of atp synthesis to electron transport, basic biochemistry
Coupling of electron transport and ATP synthesis The electrochemical gradient couples the rate of the electron transport chain to the rate of ATP synthesis. This is why energy can be stored as a combination of these two gradients across the membrane. They use mobile, lipid-soluble carriers quinones and mobile, water-soluble carriers cytochromesetc.
Some dehydrogenases are proton pumps; others are not. It occurs with chemical compounds, known as uncouplers, and it occurs physiologically with uncoupling proteins that form proton conductance channels through the membrane.
Diffusion force caused by a concentration gradient - all particles tend to diffuse from higher concentration to lower.
NADH and FADH2 cannot be oxidized as rapidly in the electron transport chain, and consequently, their build-up inhibits the enzymes that generate them. Anions diffuse spontaneously in the opposite direction.
Aerobic bacteria use a number of different terminal oxidases.
The prevailing view was that the energy of electron transfer was stored as a stable high potential intermediate, a chemically more conservative concept. They also contain a proton pump.
Organisms that use organic molecules as an energy source are called organotrophs. The free energy is used to drive ATP synthesis, catalyzed by the F1 component of the complex. Bacteria select their electron transport chains from a DNA library containing multiple possible dehydrogenases, terminal oxidases and terminal reductases.
The proton pumps of the electron transport chain respond with increased proton pumping and electron flow to maintain the electrochemical gradient. This was a radical proposal at the time, and was not well accepted.
These gradients - charge difference and the proton concentration difference both create a combined electrochemical gradient across the membrane, often expressed as the proton-motive force PMF. In mitochondria the terminal membrane complex Complex IV is cytochrome oxidase. The movement of ions across the membrane depends on a combination of two factors: It can be described as the measure of the potential energy stored as a combination of proton and voltage electrical potential gradients across a membrane.
This process of reverse electron transport is important in many prokaryotic electron transport chains.