Reverse Krebs cycle

The reverse Krebs cycle (also known as the reverse tricarboxylic acid cycle, the reverse TCA cycle, or the reverse citric acid cycle) is a sequence of chemical reactions that are used by some bacteria to produce carbon compounds from carbon dioxide and water.

The reaction is basically the Citric acid cycle run in reverse. Where the Krebs cycle takes complex carbon molecules in the form of sugars and oxidizes them to CO₂ and water, the reverse cycle takes CO₂ and water to make carbon compounds.This process is used by some bacteria to synthesise carbon compounds, sometimes using hydrogen or sulphates as electron donors. [cite journal
journal=Proc Natl Acad Sci U S A.
year=1966
month=Apr
volume=55
issue=4
pages=928–34
title=A new ferredoxin-dependent carbon reduction cycle in a photosynthetic bacterium.
author=Evans MC
coauthors=Buchanan BB; Arnon DI
pmid=5219700
doi=10.1073/pnas.55.4.928 ] [cite journal
journal=Photosynth Res
year=1990
volume=24
pages=47–53
title=A reverse KREBS cycle in photosynthesis: consensus at last.
author=Buchanan BB
coauthors=Arnon DI.
pmid=11540925
doi=10.1007/BF00032643 ] In this process it can be seen as an alternative to the far more common photosynthesis production of organic molecules.

The reaction is one of the possible candidates for prebiotic early earth conditions and so is of interest in the origin of life research. It has been found that some of the steps can be catalysed by minerals. [cite journal
title=Driving Parts of Krebs Cycle in Reverse through Mineral Photochemistry
journal=J. Am. Chem. Soc.
volume=128
issue=50
pages=16032–16033
year=2006
month=Dec
doi=10.1021/ja066103k
author=Xiang V. Zhang
coauthors=Scot T. Martin
pmid=17165745 ]

ee also

*Carbon fixation

References

External links

* [http://www.chemistry.org/portal/a/c/s/1/feature_ent.html?id=c373e9105d7044d18f6a17245d830100 Prebiotic Soup: Ugly, Yet Simmering with Metabolic Potential]