Ketogenesis is the biochemical process through which organisms produce ketone bodies by breaking down fatty acids and ketogenic amino acids. The process supplies energy to certain organs, particularly the brain, heart and skeletal muscle, under specific scenarios including fasting, caloric restriction, sleep, or others.
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.
Propionyl-CoA is a coenzyme A derivative of propionic acid. It is composed of a 24 total carbon chain and its production and metabolic fate depend on which organism it is present in. Several different pathways can lead to its production, such as through the catabolism of specific amino acids or the oxidation of odd-chain fatty acids. It later can be broken down by propionyl-CoA carboxylase or through the methylcitrate cycle. In different organisms, however, propionyl-CoA can be sequestered into controlled regions, to alleviate its potential toxicity through accumulation. Genetic deficiencies regarding the production and breakdown of propionyl-CoA also have great clinical and human significance.
Serine dehydratase or L-serine ammonia lyase (SDH) is in the β-family of pyridoxal phosphate-dependent (PLP) enzymes. SDH is found widely in nature, but its structural and properties vary among species. SDH is found in yeast, bacteria, and the cytoplasm of mammalian hepatocytes. SDH catalyzes is the deamination of L-serine to yield pyruvate, with the release of ammonia.
The crotonase family comprises mechanistically diverse proteins that share a conserved trimeric quaternary structure, the core of which consists of 4 turns of a (beta/beta/alpha)n superhelix.
Nitrosopumilus maritimus is an extremely common archaeon living in seawater. It is the first member of the Group 1a Nitrososphaerota to be isolated in pure culture. Gene sequences suggest that the Group 1a Nitrososphaerota are ubiquitous with the oligotrophic surface ocean and can be found in most non-coastal marine waters around the planet. It is one of the smallest living organisms at 0.2 micrometers in diameter. Cells in the species N. maritimus are shaped like peanuts and can be found both as individuals and in loose aggregates. They oxidize ammonia to nitrite and members of N. maritimus can oxidize ammonia at levels as low as 10 nanomolar, near the limit to sustain its life. Archaea in the species N. maritimus live in oxygen-depleted habitats. Oxygen needed for ammonia oxidation might be produced by novel pathway which generates oxygen and dinitrogen. N. maritimus is thus among organisms which are able to produce oxygen in dark.
The enzyme 3-hydroxybutyryl-CoA dehydratase (EC 4.2.1.55) catalyzes the chemical reaction
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.
In molecular biology, the citrate synthase family of proteins includes the enzymes citrate synthase EC 2.3.3.1, and the related enzymes 2-methylcitrate synthase EC 2.3.3.5 and ATP citrate lyase EC 2.3.3.8.
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.
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
Malonyl CoA reductase (malonate semialdehyde-forming) (EC 1.2.1.75, NADP-dependent malonyl CoA reductase, malonyl CoA reductase (NADP)) is an enzyme with systematic name malonate semialdehyde:NADP+ oxidoreductase (malonate semialdehyde-forming). This enzyme catalyse 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
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
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
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
The enzyme 2-hydroxypropyl-CoM lyase (EC 4.4.1.23, epoxyalkane:coenzyme M transferase, epoxyalkane:CoM transferase, epoxyalkane:2-mercaptoethanesulfonate transferase, coenzyme M-epoxyalkane ligase, epoxyalkyl:CoM transferase, epoxypropane:coenzyme M transferase, epoxypropyl:CoM transferase, EaCoMT, 2-hydroxypropyl-CoM:2-mercaptoethanesulfonate lyase (epoxyalkane-ring-forming), (R)-2-hydroxypropyl-CoM 2-mercaptoethanesulfonate lyase (cyclizing, (R)-1,2-epoxypropane-forming)) is an enzyme with systematic name (R)-[or (S)]-2-hydroxypropyl-CoM:2-mercaptoethanesulfonate lyase (epoxyalkane-ring-forming). This enzyme catalyses the following reaction:
3-Hydroxypropionyl-CoA synthase is an enzyme with systematic name hydroxypropionate:CoA ligase (AMP-forming). This enzyme catalyses the following chemical reaction
3-Hydroxybenzoate—CoA ligase is an enzyme with systematic name 3-hydroxybenzoate:CoA ligase (AMP-forming). This enzyme catalyses the following chemical reaction
