The Archaea are single-celled organisms and a domain unto themselves, quite apart from the so called eukaryotes, being bacteria and higher organisms. Many species live under extreme conditions, and carry out unique biochemical processes shared neither with bacteria nor with eukaryotes. Methanogenic archaeans, for example, can produce methane gas out of carbon dioxide and hydrogen. The underlying chemical reaction, a reduction, involves the cofactor known as F0 or F420 which is the tiny molecule deazaflavin. It has previously been found only in methanogenic bacteria, and has accordingly been considered the signature molecule for those species. A research group working with Professor Thomas Carell, however, has now shown that this cofactor is also common in eukaryotes, where it performs an entirely different function: deazaflavin is involved in DNA repair processes. (PNAS Early Edition online, 1 July 2009)
Catalysts assist in chemical reactions without undergoing any alteration of their own. In the cells of living organisms, proteins perform this important function. They carry out the metabolism fundamental to all living processes. Proteins are instrumental in cellular respiration, they for instance reduce oxygen to water and oxidize food into carbon dioxide. This releases the energy that makes life possible at all. Proteins cannot perform these functions on their own. They depend on small helper molecules. Such molecules are stored inside special pockets in the proteins and carry out essential metabolic functions. The living organism itself produces many of these helpers. Others like vitamins must be obtained from food. Severe vitamin deficiencies are a harsh reminder of how essential these molecules are.
Methanogenic bacteria have quite an exceptional task to accomplish: They have to produce methane. In terms of chemistry, this is no mean feat. Methane production is currently one of the most hotly pursued goals for the purposes of re
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