Threonine is an amino acid that is used in the biosynthesis of proteins. It contains an α-amino group, a carboxyl group, and a side chain containing a hydroxyl group, making it a polar, uncharged amino acid. It is essential in humans, meaning the body cannot synthesize it: it must be obtained from the diet. Threonine is synthesized from aspartate in bacteria such as E. coli. It is encoded by all the codons starting AC.
Glutamate dehydrogenase is an enzyme observed in both prokaryotes and eukaryotic mitochondria. The aforementioned reaction also yields ammonia, which in eukaryotes is canonically processed as a substrate in the urea cycle. Typically, the α-ketoglutarate to glutamate reaction does not occur in mammals, as glutamate dehydrogenase equilibrium favours the production of ammonia and α-ketoglutarate. Glutamate dehydrogenase also has a very low affinity for ammonia, and therefore toxic levels of ammonia would have to be present in the body for the reverse reaction to proceed. However, in brain, the NAD+/NADH ratio in brain mitochondria encourages oxidative deamination. In bacteria, the ammonia is assimilated to amino acids via glutamate and aminotransferases. In plants, the enzyme can work in either direction depending on environment and stress. Transgenic plants expressing microbial GLDHs are improved in tolerance to herbicide, water deficit, and pathogen infections. They are more nutritionally valuable.
Isocitrate dehydrogenase (IDH) (EC 1.1.1.42) and (EC 1.1.1.41) is an enzyme that catalyzes the oxidative decarboxylation of isocitrate, producing alpha-ketoglutarate (α-ketoglutarate) and CO2. This is a two-step process, which involves oxidation of isocitrate (a secondary alcohol) to oxalosuccinate (a ketone), followed by the decarboxylation of the carboxyl group beta to the ketone, forming alpha-ketoglutarate. In humans, IDH exists in three isoforms: IDH3 catalyzes the third step of the citric acid cycle while converting NAD+ to NADH in the mitochondria. The isoforms IDH1 and IDH2 catalyze the same reaction outside the context of the citric acid cycle and use NADP+ as a cofactor instead of NAD+. They localize to the cytosol as well as the mitochondrion and peroxisome.
Amino acid synthesis is the set of biochemical processes by which the amino acids are produced. The substrates for these processes are various compounds in the organism's diet or growth media. Not all organisms are able to synthesize all amino acids. For example, humans can synthesize 11 of the 20 standard amino acids. These 11 are called the non-essential amino acids).
3-Isopropylmalate dehydratase is an aconitase homologue, which catalyses the isomerisation of 2-isopropylmalate to 3-isopropylmalate, via dehydration, in the biosynthesis of leucine.
In enzymology, a dimethylmalate dehydrogenase (EC 1.1.1.84) is an enzyme that catalyzes the chemical reaction
In enzymology, a homoisocitrate dehydrogenase (EC 1.1.1.87) is an enzyme that catalyzes the chemical reaction
In enzymology, a ketol-acid reductoisomerase (EC 1.1.1.86) is an enzyme that catalyzes the chemical reaction
In enzymology, a pantoate 4-dehydrogenase (EC 1.1.1.106) is an enzyme that catalyzes the chemical reaction
In enzymology, a sterol-4alpha-carboxylate 3-dehydrogenase (decarboxylating) (EC 1.1.1.170) is an enzyme that catalyzes the chemical reaction
In enzymology, a 3alpha(or 20beta)-hydroxysteroid dehydrogenase (EC 1.1.1.53) is an enzyme that catalyzes the chemical reaction
In enzymology, a 3-hydroxy-2-methylbutyryl-CoA dehydrogenase (EC 1.1.1.178) is an enzyme that catalyzes the chemical reaction
In enzymology, a (R)-2-hydroxyacid dehydrogenase (EC 1.1.1.272) is an enzyme that catalyzes the chemical reaction
In enzymology, a 2-oxoisovalerate dehydrogenase (acylating) (EC 1.2.1.25) is an enzyme that catalyzes the chemical reaction
In enzymology, a leucine dehydrogenase (EC 1.4.1.9) is an enzyme that catalyzes the chemical reaction
The enzyme branched-chain-2-oxoacid decarboxylase (EC 4.1.1.72) catalyzes the chemical reaction
In enzymology, a 2-isopropylmalate synthase (EC 2.3.3.13) is an enzyme that catalyzes the chemical reaction
UDP-N-acetyl-2-amino-2-deoxyglucuronate dehydrogenase (EC 1.1.1.335, WlbA, WbpB) is an enzyme with systematic name UDP-N-acetyl-2-amino-2-deoxy-alpha-D-glucuronate:NAD+ 3-oxidoreductase. This enzyme catalyses the following chemical reaction:
L-2-hydroxycarboxylate dehydrogenase (NAD+) (EC 1.1.1.337, (R)-sulfolactate:NAD+ oxidoreductase, L-sulfolactate dehydrogenase, (R)-sulfolactate dehydrogenase, L-2-hydroxyacid dehydrogenase (NAD+), ComC) is an enzyme with systematic name (2S)-2-hydroxycarboxylate:NAD+ oxidoreductase. This enzyme catalyses the following chemical reaction
Isopropylmalic acid (isopropylmalate) is an intermediate in the biosynthesis of leucine, synthesized from oxoisovalerate by 2-isopropylmalate synthase and converted into isopropyl-3-oxosuccinate by 3-isopropylmalate dehydrogenase. Two isomers are important, the 2- and 3-isopropyl derivatives, and these are interconverted by isopropylmalate dehydratase.
