Biological methane oxidation

Lieberman, R. L. Rosenzweig, A. C. Biological methane oxidation regulation, biochemistry, and active site structure of particulate methane monooxygenase. Crit. Rev. Biochem. Mol. Biol. 2004, 39(3), 147-164. 

Methanotrophs, which are widespread in aquatic and terrestrial environments, carry out methane oxidation in most habitats where methane and oxygen coexist (3). On a global scale, these bacteria are responsible for a major portion of the biological methane consumption that occurs on the earth s surface. Therefore, a great deal of interest exists concerning their role in global methane cycling (4). 

Nickel is an analogue of platinum and its oxidation state at which methane is produced is Ni(II) with a d electronic configuration, that is the same as that of Pt(II) which activates methane and other alkanes (see Chapter VII). Evidently the activation of methane on platinum complexes may be considered a conditional model for biological anaerobic oxidation of alkanes. It is of importance that Ni(II) as well as Pt(II) is a so-called soft acid and could prefer to react with methane ( soft base) rather than with such strong hard base as water, therefore surrounding water does not prevent this reaction. 

The massive reservoir of available oxygen as ferric iron in hard rocks played a major role in the build-up to an oxygen atmosphere. Hydrogen escape to space before 2.45 m.y. produced this reservoir. Biological methane carried hydrogen to the top of the atmosphere and biological hydrogen escaped. This process has not detectably affected the oxidation state of the massive mantle reservoir. 

Arif, M A S., Houwen, F, Verstraete, W. 1996. Agricultural factors affecting methane oxidation in arable soil. Biology and Fertility of Soils 21(1-2) 95-102. 

Chistoserdova, L., Vorholt, J.A., and Lidstrom, M.E. 2005. A genomic view of methane oxidation by aerobic bacteria and anaerobic archaea. Genome Biology 6 208. 

Hiitsch, B.W. 1998. Methane oxidation in arable soil as inhibited by ammonitun, nitrite, and organic manure with respect to soil pH. Biology and Fertility of Soils 28(1) 27-35. 

Wang, Z.P., Ineson, P. 2003. Methane oxidation in a temperate coniferous forest soil effects of inorganic N. Soil Biology and Biochemistry 35(3) 427-433. 

The production of reduced products like methane and ammonia by the gut microbial flora has important environmental consequences, as such compounds contribute to the chemical and biological oxygen demand. The detection of dissolved oxygen in the gut of piglets led to tests to show whether methane and other reduced products could be oxidized in the pig gut. The production of C-labelledCOj from C-labelledmethane has been demonstrated however, it is calculated that at most only a very small proportion of methane produced is likely to be oxidized using O 2 as electron acceptor. Methane may also be oxidized anaerobically, but only an extremely small amount of methane is likely to... 

Results discussed above show in several lines a distinct biomimetic-type activity of iron complexes stabilized in the ZSM-S matrix. The most important feature is their unique ability to coordinate a very reactive a-oxygen form which is similar to the active oxygen species of MMO. At room temperature a-oxygen provides various oxidation reactions including selective hydroxylation of methane to methanol. Like in biological oxidation, the rate determining step of this reaction involves the cleavage of C-H bond. 

Lieberman, R.L. and Rosenzweig, A.C. (2005) Crystal structure of a membrane-bound metalloenzyme that catalyses the biological oxidation of methane, Nature, 434, 177-182. 

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