Title: New insights into the origin of life on Earth
Authors: Xiang V. Zhang and Scot T. Martin

In an advance toward understanding the origin of life on Earth, scientists have shown that parts of the Krebs cycle can run in reverse, producing biomolecules that could jump-start life with only sunlight and a mineral present in the primordial oceans. The Krebs cycle is a series of chemical reactions of central importance in cells — part of a metabolic pathway that changes carbohydrates, fats and proteins into carbon dioxide and water to generate energy.
Scot T. Martin and Xiang V. Zhang explain that a reverse version of the cycle, which makes enzymes and other biomolecules from carbon dioxide, has been getting attention from scientists studying the origin of life. If the reverse cycle worked on a lifeless Earth, it could have produced the fundamental biochemicals needed for the development of more-advanced biological systems like RNA that could reproduce themselves.
In a report scheduled for the Dec. 13 issue of the weekly Journal of the American Chemical Society, Martin and Zhang demonstrate that three of the five chemical reactions in the reverse Krebs cycle worked and produced biomolecules on the surface of a mineral believed to have been present in the waters of the early Earth. The mineral -- sphalerite -- acted as a photocatalyst that worked with sunlight to foster the chemical reactions.

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Source Journal of the American Chemical Society

Read more Weblink: “Driving Parts of Krebs Cycle in Reverse through Mineral Photochemistry”.

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`Irony` actually does mean `metal like`...

Nice article Blob. By the way, sphalerite is ZnS, usually with a few percent iron in the mineral. The synthetic version has been studied as a photoelectric and photoelectrochemical material - very consistent with this work.

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At night the stars put on a show for free (Carole King)

That bit is painful to read. A reversed Krebs cycle will not "make enzymes."

Hum,
This work is outside my field of knowledge so i can't comment...

http://en.wikipedia.org/wiki/Citric_acid_cycle

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`Irony` actually does mean `metal like`...

Krebs cycle is aerobic sugar metabolism. No amino acids are made or destroyed by the pathway. Enzymes are proteins, that is, they are made up of strings of amino acids.

Interesting.