Reverse electron flow

Biochemical process in cellular respiration

Template:Infobox biochemical pathway

Reverse electron flow is a biochemical process that occurs in certain microorganisms and is part of their metabolic pathways. This process is essential for the generation of reducing power in the form of NADH or NADPH, which are crucial for various biosynthetic reactions.

Mechanism

In reverse electron flow, electrons are transferred from a donor with a lower reduction potential to an acceptor with a higher reduction potential, against the thermodynamic gradient. This process requires the input of energy, which is typically derived from the proton motive force generated by the electron transport chain.

The reverse electron flow is often observed in chemolithoautotrophs, which are organisms that obtain energy by oxidizing inorganic substances. These organisms use reverse electron flow to generate NADH from NAD+ when the direct reduction of NAD+ is not thermodynamically favorable.

Biological Significance

Reverse electron flow is significant in the carbon fixation pathways of certain bacteria, such as the Calvin cycle in cyanobacteria and some purple bacteria. It allows these organisms to assimilate carbon dioxide into organic compounds, which is vital for their growth and survival.

Examples

One example of reverse electron flow is found in the sulfur-oxidizing bacteria, where electrons from the oxidation of sulfur compounds are used to reduce NAD+ to NADH. Another example is in the nitrifying bacteria, which oxidize ammonia to nitrite and use reverse electron flow to generate reducing power for carbon assimilation.

See also

• Electron transport chain
• Proton motive force
• Chemolithoautotrophy
• Carbon fixation

External links

• Reverse Electron Flow on WikiMD