Biological carbon fixation or сarbon assimilation is the process by which inorganic carbon is converted to organic compounds by living organisms. The compounds are then used to store energy and as structure for other biomolecules. Carbon is primarily fixed through photosynthesis, but some organisms use a process called chemosynthesis in the absence of sunlight.
An acetogen is a microorganism that generates acetate (CH3COO−) as an end product of anaerobic respiration or fermentation. However, this term is usually employed in a narrower sense only to those bacteria and archaea that perform anaerobic respiration and carbon fixation simultaneously through the reductive acetyl coenzyme A (acetyl-CoA) pathway (also known as the Wood-Ljungdahl pathway). These genuine acetogens are also known as "homoacetogens" and they can produce acetyl-CoA (and from that, in most cases, acetate as the end product) from two molecules of carbon dioxide (CO2) and four molecules of molecular hydrogen (H2). This process is known as acetogenesis, and is different from acetate fermentation, although both occur in the absence of molecular oxygen (O2) and produce acetate. Although previously thought that only bacteria are acetogens, some archaea can be considered to be acetogens.
The reverse Krebs cycle is a sequence of chemical reactions that are used by some bacteria to produce carbon compounds from carbon dioxide and water by the use of energy-rich reducing agents as electron donors.
Fatty-acyl-CoA Synthase, or more commonly known as yeast fatty acid synthase, is an enzyme complex responsible for fatty acid biosynthesis, and is of Type I Fatty Acid Synthesis (FAS). Yeast fatty acid synthase plays a pivotal role in fatty acid synthesis. It is a 2.6 MDa barrel shaped complex and is composed of two, unique multi-functional subunits: alpha and beta. Together, the alpha and beta units are arranged in an α6β6 structure. The catalytic activities of this enzyme complex involves a coordination system of enzymatic reactions between the alpha and beta subunits. The enzyme complex therefore consists of six functional centers for fatty acid synthesis.
The 3-hydroxypropionate bicycle, also known as the 3-hydroxypropionate pathway, is a process that allows some bacteria to generate 3-hydroxypropionate usingcarbon dioxide. In this pathway CO2 is fixed (i.e. incorporated) by the action of two enzymes, acetyl-CoA carboxylase and propionyl-CoA carboxylase. These enzymes generate malonyl-CoA and (S)-methylmalonyl-CoA, respectively. Malonyl-CoA, in a series of reactions, is further split into acetyl-CoA and glyoxylate. Glyoxylate is incorporated into beta-methylmalyl-coA which is then split, again through a series of reactions, to release pyruvate as well as acetate, which is used to replenish the cycle. This pathway has been demonstrated in Chloroflexus, a nonsulfur photosynthetic bacterium; however, other studies suggest that 3-hydroxypropionate bicycle is used by several chemotrophic archaea.
Cobalamin biosynthesis is the process by which bacteria and archea make cobalamin, vitamin B12. Many steps are involved in converting aminolevulinic acid via uroporphyrinogen III and adenosylcobyric acid to the final forms in which it is used by enzymes in both the producing organisms and other species, including humans who acquire it through their diet.
In molecular biology, the HMG-CoA reductase family is a family of enzymes which participate in the mevalonate pathway, the metabolic pathway that produces cholesterol and other isoprenoids.
The gab operon is responsible for the conversion of γ-aminobutyrate (GABA) to succinate. The gab operon comprises three structural genes – gabD, gabT and gabP – that encode for a succinate semialdehyde dehydrogenase, GABA transaminase and a GABA permease respectively. There is a regulatory gene csiR, downstream of the operon, that codes for a putative transcriptional repressor and is activated when nitrogen is limiting.
3-hydroxypropionate dehydrogenase (NADP+) (EC 1.1.1.298) is an enzyme with systematic name 3-hydroxypropionate:NADP+ oxidoreductase. This enzyme catalyses the following chemical reaction
2-hydroxy-4-carboxymuconate semialdehyde hemiacetal dehydrogenase (EC 1.1.1.312, 2-hydroxy-4-carboxymuconate 6-semialdehyde dehydrogenase, 4-carboxy-2-hydroxy-cis,cis-muconate-6-semialdehyde:NADP+ oxidoreductase, alpha-hydroxy-gamma-carboxymuconic epsilon-semialdehyde dehydrogenase, 4-carboxy-2-hydroxymuconate-6-semialdehyde dehydrogenase, LigC, ProD) is an enzyme with systematic name 4-carboxy-2-hydroxymuconate semialdehyde hemiacetal:NADP+ 2-oxidoreductase. This enzyme catalyses the following chemical reaction
Succinate-semialdehyde dehydrogenase (acylating) (EC 1.2.1.76, succinyl-coA reductase, coenzyme-A-dependent succinate-semialdehyde dehydrogenase) is an enzyme with systematic name succinate semialdehyde:NADP+ oxidoreductase (CoA-acylating). This enzyme catalyses the following chemical reaction
3,4-Dehydroadipyl-CoA semialdehyde dehydrogenase (NADP+) (EC 1.2.1.77, BoxD, 3,4-dehydroadipyl-CoA semialdehyde dehydrogenase) is an enzyme with systematic name 3,4-didehydroadipyl-CoA semialdehyde:NADP+ oxidoreductase. This enzyme catalyses the following chemical reaction
Succinate-semialdehyde dehydrogenase (NADP+) (EC 1.2.1.79, succinic semialdehyde dehydrogenase (NADP+), succinyl semialdehyde dehydrogenase (NADP+), succinate semialdehyde:NADP+ oxidoreductase, NADP-dependent succinate-semialdehyde dehydrogenase, GabD) is an enzyme with systematic name succinate-semialdehyde:NADP+ oxidoreductase. This enzyme catalyses the following chemical reaction
Acrylyl-CoA reductase (NADPH) (EC 1.3.1.84) is an enzyme with systematic name propanoyl-CoA:NADP+ oxidoreductase. This enzyme catalyses the following chemical reaction
Benzoyl-CoA 2,3-dioxygenase (EC 1.14.12.21, benzoyl-CoA dioxygenase/reductase, BoxBA, BoxA/BoxB system) is an enzyme with systematic name benzoyl-CoA,NADPH:oxygen oxidoreductase (2,3-hydroxylating). This enzyme catalyses the following chemical reaction
Oxepin-CoA hydrolase (EC 3.7.1.16, paaZ (gene)) is an enzyme with systematic name 2-oxepin-2(3H)-ylideneacetyl-CoA hydrolyase. This enzyme catalyses the following chemical reaction
3-hydroxypropionyl-CoA dehydratase (EC 4.2.1.116) is an enzyme with systematic name 3-hydroxypropionyl-CoA hydro-lyase. This enzyme catalyses the following chemical reaction
4-hydroxybutanoyl-CoA dehydratase (EC 4.2.1.120) is an enzyme with systematic name 4-hydroxybutanoyl-CoA hydro-lyase. This enzyme catalyses the following chemical reaction
3-Hydroxypropionyl-CoA synthase is an enzyme with systematic name hydroxypropionate:CoA ligase (AMP-forming). This enzyme catalyses the following chemical reaction
Azoarcus evansii is a species of bacteria. Its type strain is KB 740T.
