|
Methanogenesis
Methanogenesis or biomethanation is the formation of methane coupled to energy conservation by microbes known as methanogens. Organisms capable of producing methane for energy conservation have been identified only from the domain Archaea, a group phylogenetically distinct from both eukaryotes and bacteria, although many live in close association with anaerobic bacteria. Other forms of methane production that are not coupled to ATP synthesis exist within all three domains of life. The production of methane is an important and widespread form of microbial metabolism. In anoxic environments, it is the final step in the decomposition of biomass. Methanogenesis is responsible for significant amounts of natural gas accumulations, the remainder being thermogenic. Biochemistry Methanogenesis in microbes is a form of anaerobic respiration. Methanogens do not use oxygen to respire; in fact, oxygen inhibits the growth of methanogens. The terminal electron acceptor in methanogenesis i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methanogenesis Cycle
Methanogenesis or biomethanation is the formation of methane coupled to energy conservation by microbes known as methanogens. Organisms capable of producing methane for energy conservation have been identified only from the domain Archaea, a group phylogenetically distinct from both eukaryotes and bacteria, although many live in close association with anaerobic bacteria. Other forms of methane production that are not coupled to ATP synthesis exist within all three domains of life. The production of methane is an important and widespread form of microbial metabolism. In anoxic environments, it is the final step in the decomposition of biomass. Methanogenesis is responsible for significant amounts of natural gas accumulations, the remainder being thermogenic. Biochemistry Methanogenesis in microbes is a form of anaerobic respiration. Methanogens do not use oxygen to respire; in fact, oxygen inhibits the growth of methanogens. The terminal electron acceptor in methanogenesis is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methane
Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Earth makes it an economically attractive fuel, although capturing and storing it poses technical challenges due to its gaseous state under normal conditions for temperature and pressure. Naturally occurring methane is found both below ground and under the seafloor and is formed by both geological and biological processes. The largest reservoir of methane is under the seafloor in the form of methane clathrates. When methane reaches the surface and the atmosphere, it is known as atmospheric methane. The Earth's atmospheric methane concentration has increased by about 150% since 1750, and it accounts for 20% of the total radiative forcing from all of the long-lived and globally mixed greenhouse gases. It has also been detected on other pl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methane
Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Earth makes it an economically attractive fuel, although capturing and storing it poses technical challenges due to its gaseous state under normal conditions for temperature and pressure. Naturally occurring methane is found both below ground and under the seafloor and is formed by both geological and biological processes. The largest reservoir of methane is under the seafloor in the form of methane clathrates. When methane reaches the surface and the atmosphere, it is known as atmospheric methane. The Earth's atmospheric methane concentration has increased by about 150% since 1750, and it accounts for 20% of the total radiative forcing from all of the long-lived and globally mixed greenhouse gases. It has also been detected on other pl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Archaea
Archaea ( ; singular archaeon ) is a domain of single-celled organisms. These microorganisms lack cell nuclei and are therefore prokaryotes. Archaea were initially classified as bacteria, receiving the name archaebacteria (in the Archaebacteria kingdom), but this term has fallen out of use. Archaeal cells have unique properties separating them from the other two domains, Bacteria and Eukaryota. Archaea are further divided into multiple recognized phyla. Classification is difficult because most have not been isolated in a laboratory and have been detected only by their gene sequences in environmental samples. Archaea and bacteria are generally similar in size and shape, although a few archaea have very different shapes, such as the flat, square cells of '' Haloquadratum walsbyi''. Despite this morphological similarity to bacteria, archaea possess genes and several metabolic pathways that are more closely related to those of eukaryotes, notably for the enzymes invo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coenzyme M
Coenzyme M is a coenzyme required for methyl-transfer reactions in the metabolism of archaeal methanogens, and in the metabolism of other substrates in bacteria. It is also a necessary cofactor in the metabolic pathway of alkene-oxidizing bacteria. CoM helps eliminate the toxic epoxides formed from the oxidation of alkenes such as propylene. The structure of this coenzyme was discovered by CD Taylor and RS Wolfe in 1974 while they were studying methanogenesis, the process by which carbon dioxide is transformed into methane in some anaerobic bacteria. The coenzyme is an anion with the formula . It is named 2-mercaptoethanesulfonate and abbreviated HS–CoM. The cation is unimportant, but the sodium salt is most available. Mercaptoethanesulfonate contains both a thiol, which is the main site of reactivity, and a sulfonate group, which confers solubility in aqueous media. Biochemical role Methanogenesis The coenzyme is the C1 donor in methanogenesis. It is converted to methyl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coenzyme B
Coenzyme B is a coenzyme required for redox reactions in methanogens. The full chemical name of coenzyme B is 7-mercaptoheptanoylthreoninephosphate. The molecule contains a thiol, which is its principal site of reaction. Coenzyme B reacts with 2-methylthioethanesulfonate (methyl- Coenzyme M, abbreviated ), to release methane in methanogenesis: : + HS–CoB → + CoB–S–S–CoM This conversion is catalyzed by the enzyme methyl coenzyme M reductase, which contains cofactor F430 as the prosthetic group. A related conversion that utilizes both HS-CoB and HS-CoM is the reduction of fumarate Fumaric acid is an organic compound with the formula HO2CCH=CHCO2H. A white solid, fumaric acid occurs widely in nature. It has a fruit-like taste and has been used as a food additive. Its E number is E297. The salts and esters are known as f ... to succinate, catalyzed by fumarate reductase: :HS–CoM + HS–CoB + − → − + CoB–S–S–CoM Importance of Coenzyme B ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methanogen
Methanogens are microorganisms that produce methane as a metabolic byproduct in hypoxic conditions. They are prokaryotic and belong to the domain Archaea. All known methanogens are members of the archaeal phylum Euryarchaeota. Methanogens are common in wetlands, where they are responsible for marsh gas, and in the digestive tracts of animals such as ruminants and many humans, where they are responsible for the methane content of belching in ruminants and flatulence in humans. In marine sediments, the biological production of methane, also termed methanogenesis, is generally confined to where sulfates are depleted, below the top layers. Moreover, methanogenic archaea populations play an indispensable role in anaerobic wastewater treatments. Others are extremophiles, found in environments such as hot springs and submarine hydrothermal vents as well as in the "solid" rock of Earth's crust, kilometers below the surface. Physical description Methanogens are coccoid (sph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anaerobic Respiration
Anaerobic respiration is respiration using electron acceptors other than molecular oxygen (O2). Although oxygen is not the final electron acceptor, the process still uses a respiratory electron transport chain. In aerobic organisms undergoing respiration, electrons are shuttled to an electron transport chain, and the final electron acceptor is oxygen. Molecular oxygen is an excellent electron acceptor. Anaerobes instead use less-oxidizing substances such as nitrate (), fumarate (), sulfate (), or elemental sulfur (S). These terminal electron acceptors have smaller reduction potentials than O2. Less energy per oxidized molecule is released. Therefore, anaerobic respiration is less efficient than aerobic. As compared with fermentation Anaerobic cellular respiration and fermentation generate ATP in very different ways, and the terms should not be treated as synonyms. Cellular respiration (both aerobic and anaerobic) uses highly reduced chemical compounds such as NADH an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thiyl Radical
In chemistry Chemistry is the scientific study of the properties and behavior of matter. It is a natural science that covers the elements that make up matter to the compounds made of atoms, molecules and ions: their composition, structure, propertie ..., a thiyl radical has the formula RS, sometimes written RS• to emphasize that they are free radicals. R is typically an alkyl or aryl substituent. Because S–H bonds are about 20% weaker than C–H bonds, thiyl radicals are relatively easily generated from thiols RSH. Thiyl radicals are intermediates in the thiol-ene reaction, which is the basis of some polymeric coatings and adhesives. They are generated by hydrogen-atom abstraction from thiols using initiators such as AIBN: : RN=NR → 2 R• + N2 :R• + R′SH → R′S• + RH Thiyl radicals are also invoked as intermediates in some biochemical reactions. References Free radicals Organosulfur compounds {{organic-chemistry-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methanopterin
Tetrahydromethanopterin (THMPT, ) is a coenzyme in methanogenesis. It is the carrier of the C1 group as it is reduced to the methyl level, before transferring to the coenzyme M. Tetrahydrosarcinapterin (THSPT, ) is a modified form of THMPT, wherein a glutamyl group linked to the 2-hydroxyglutaric acid terminus. THMPT is the main platform for C1 transformations N-Formyl methanofuran donates the C1 group to the N5 site of the pterin to give the formyl- THMPT. The formyl group subsequently condenses intramolecularly to give methenyl- , which is then reduced to methylene- THMPT. Methylene- MPT is subsequently converted, using coenzyme F420 as the electron source, to methyl- THMPT, catalyzed by F420-dependent methylene-THMPT reductase. Methyl- THMPT is the methyl donor to coenzyme M, a conversion mediated by methyl-THMPT:coenzyme M methyltransferase. Comparison with tetrahydrofolic acid THMPT is related to the better known tetrahydrofolic acid (THFA, ). The most importa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methanofuran
Methanofurans are a family of chemical compounds found in methanogenic archaea. These species feature a 2-aminomethylfuran linked to phenoxy group. At least three different end groups are recognized: R = tricarboxyheptanoyl (methanofuran), glutamyl-glutamyl (methanofuran b), tricarboxy-2-hydroxyheptanoyl (methanofuran c, see picture). Formylation of MFR Methanofuran converts to formylmethanofuran in an early stage of methanogenesis. The enzyme formylmethanofuran dehydrogenase ( EC: 1.2.99.5) formylates methanofuran using , the primary C1 source in methanogenesis. Deformylation of MFR The enzyme formylmethanofuran:tetrahydromethanopterin formyltransferase catalyzes the transfer of the formyl group from formylmethanofuran to N5 on tetrahydromethanopterin, . This enzyme has been crystallized; it contains no prosthetic group A prosthetic group is the non-amino acid component that is part of the structure of the heteroproteins or conjugated proteins, being tightly linked ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Formic Acid
Formic acid (), systematically named methanoic acid, is the simplest carboxylic acid, and has the chemical formula HCOOH and structure . It is an important intermediate in chemical synthesis and occurs naturally, most notably in some ants. Esters, salts and the anion derived from formic acid are called formates. Industrially, formic acid is produced from methanol. Natural occurrence In nature, formic acid is found in most ants and in stingless bees of the genus '' Oxytrigona''. Wood ants from the genus '' Formica'' can spray formic acid on their prey or to defend the nest. The puss moth caterpillar (''Cerura vinula'') will spray it as well when threatened by predators. It is also found in the trichomes of stinging nettle (''Urtica dioica''). Apart from that, this acid is incorporated in many fruits such as pineapple (0.21mg per 100g), apple (2mg per 100g) and kiwi (1mg per 100g), as well as in many vegetables, namely onion (45mg per 100g), eggplant (1.34 mg per 100g) an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.jpg "Click for more on -> Archaea")
.svg "Click for more on -> Anaerobic Respiration")
