Biological methane formation

Ermler U, W Grabarse, S Shima, M Goubeaud, RK Thauer (1997) Crystal structure of methyl-coenzyme M reductase the key enzyme of biological methane formation. Science 278 1457-1462. 

Belay N, Daniels L. 1990. Elemental metals as electron sources for biological methane formation from CO2. Antonie Leeuwenhoek 57 1-7. 

An Important area of study In organic geochemistry concerns Che origin of natural gas two of the more useful parameters In addressing this problem are 6D-CH and S C-CH. As discussed above, 6D-CH Is useful In estimating relative pathway contribution In biological methane formation. Combined with... 

The process of leachate formation in a landfill covers several phases, starting with initial decomposition to an acid forming period then to the methane formation phase. This biological process in which organic matter is catabolised to methane and carbon dioxide is anaerobic digestion. 

Transfer from the water column to the atmosphere may also occur by the formation of droplets formed as breaking waves create a spray. This is responsible for the transmission of sodium chloride into coastal areas. Bursting of bubbles at the water surface may cause very small water droplets to be propelled into the atmosphere, whereupon they become permanently incorporated into the atmosphere by turbulent eddies. This is most likely to occur in water bodies where there is significant anaerobic methane formation, or in biological oxidation units in which there is deliberate mechanical aeration of the water. It is noteworthy that such droplets may be enriched in solutes which preferentially associate with surface organic microlayers. 

Methyl coenzyme-M reductase (MCR) catalyzes the final step of methane production in methanogenic archaebacteria, which accounts for all biologically generated methane on the earth (4). The reaction involves methane formation concomitantly with the formation of a disulfide bond between coenzyme M (CoM) and coenzyme B (CoB) ... 

In order to understand the bewildering variety of reactions involving tetrahydrofolate, it is essential to realize that in biological systems, one-carbon compounds may exist in five different oxidation states. The most reduced form is methane, CH4, and the most oxidized form is C02. In between these two extremes are methanol (CH3OH), formaldehyde (CH20), and formate (HCOO ). 

Biological systems overcome the inherent unreactive character of 02 by means of metalloproteins (enzymes) that activate dioxygen for selective reaction with organic substrates. For example, the cytochrome P-450 proteins (thiolated protoporphyrin IX catalytic centers) facihtate the epoxidation of alkenes, the demethylation of Al-methylamines (via formation of formaldehyde), the oxidative cleavage of a-diols to aldehydes and ketones, and the monooxygenation of aliphatic and aromatic hydrocarbons (RH) (equation 104). The methane monooxygenase proteins (MMO, dinuclear nonheme iron centers) catalyze similar oxygenation of saturated hydrocarbons (equation 105). ... 

Beyond metabolism of carbohydrates, there are several other biological processes common in prokaryotes that consume oxygen. For example, methylotrophic organisms can metabolize Ci compounds such as methane, methanol, formaldehyde, and formate, as in... 

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