Lysine (symbol Lys or K) is an α-amino acid that is a precursor to many proteins. It contains an α-amino group (which is in the protonated −NH+
3 form under biological conditions), an α-carboxylic acid group (which is in the deprotonated −COO− form under biological conditions), and a side chain lysyl ((CH2)4NH2), classifying it as a basic, charged (at physiological pH), aliphatic amino acid. It is encoded by the codons AAA and AAG. Like almost all other amino acids, the α-carbon is chiral and lysine may refer to either enantiomer or a racemic mixture of both. For the purpose of this article, lysine will refer to the biologically active enantiomer L-lysine, where the α-carbon is in the S configuration.
In molecular biology, biosynthesis is a multi-step, enzyme-catalyzed process where substrates are converted into more complex products in living organisms. In biosynthesis, simple compounds are modified, converted into other compounds, or joined to form macromolecules. This process often consists of metabolic pathways. Some of these biosynthetic pathways are located within a single cellular organelle, while others involve enzymes that are located within multiple cellular organelles. Examples of these biosynthetic pathways include the production of lipid membrane components and nucleotides. Biosynthesis is usually synonymous with anabolism.
In enzymology, a homoisocitrate dehydrogenase (EC 1.1.1.87) is an enzyme that catalyzes the chemical reaction
In enzymology, a flavonol synthase is an enzyme that catalyzes the following chemical reaction :
In enzymology, a leucocyanidin oxygenase (EC 1.14.11.19) is an enzyme that catalyzes the chemical reaction
In enzymology, a saccharopine dehydrogenase (NADP+, L-lysine-forming) (EC 1.5.1.8) is an enzyme that catalyzes the chemical reaction
In enzymology, an aerobactin synthase (EC 6.3.2.39) is an enzyme that catalyzes the chemical reaction
The enzyme homoaconitate hydratase (EC 4.2.1.36) catalyzes the chemical reaction
In enzymology, a 2-ethylmalate synthase (EC 2.3.3.6) is an enzyme that catalyzes the chemical reaction
In enzymology, a 2-isopropylmalate synthase (EC 2.3.3.13) is an enzyme that catalyzes the chemical reaction
In enzymology, a 2-methylcitrate synthase (EC 2.3.3.5) is an enzyme that catalyzes the chemical reaction
In enzymology, a citrate (Re)-synthase (EC 2.3.3.3) is an enzyme that catalyzes the chemical reaction
In enzymology, a decylhomocitrate synthase (EC 2.3.3.4) is an enzyme that catalyzes the chemical reaction
In molecular biology, hydroxymethylglutaryl-CoA synthase or HMG-CoA synthase EC 2.3.3.10 is an enzyme which catalyzes the reaction in which acetyl-CoA condenses with acetoacetyl-CoA to form 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA). This reaction comprises the second step in the mevalonate-dependent isoprenoid biosynthesis pathway. HMG-CoA is an intermediate in both cholesterol synthesis and ketogenesis. This reaction is overactivated in patients with diabetes mellitus type 1 if left untreated, due to prolonged insulin deficiency and the exhaustion of substrates for gluconeogenesis and the TCA cycle, notably oxaloacetate. This results in shunting of excess acetyl-CoA into the ketone synthesis pathway via HMG-CoA, leading to the development of diabetic ketoacidosis.
In enzymology, a L,L-diaminopimelate aminotransferase (EC 2.6.1.83) is an enzyme that catalyzes the chemical reaction
In enzymology, a N6-acetyl-beta-lysine transaminase is an enzyme that catalyzes the chemical reaction
Alpha-aminoadipic semialdehyde synthase is an enzyme encoded by the AASS gene in humans and is involved in their major lysine degradation pathway. It is similar to the separate enzymes coded for by the LYS1 and LYS9 genes in yeast, and related to, although not similar in structure, the bifunctional enzyme found in plants. In humans, mutations in the AASS gene, and the corresponding alpha-aminoadipic semialdehyde synthase enzyme are associated with familial hyperlysinemia. This condition is inherited in an autosomal recessive pattern and is not considered a particularly negative condition, thus making it a rare disease.
The α-aminoadipate pathway is a biochemical pathway for the synthesis of the amino acid L-lysine. In the eukaryotes, this pathway is unique to the higher fungi and the euglenids. It has also been reported from bacteria of the genus Thermus.
Methanogen homoaconitase (EC 4.2.1.114, methanogen HACN) is an enzyme with systematic name (R)-2-hydroxybutane-1,2,4-tricarboxylate hydro-lyase ((1R,2S)-1-hydroxybutane-1,2,4-tricarboxylate-forming). This enzyme catalyses the following chemical reaction
N2-citryl-N6-acetyl-N6-hydroxylysine synthase (EC 6.3.2.38, N(alpha)-citryl-N(epsilon)-acetyl-N(epsilon)-hydroxylysine synthase, iucA (gene)) is an enzyme with systematic name citrate:N6-acetyl-N6-hydroxy-L-lysine ligase (ADP-forming). This enzyme catalyses the following chemical reaction
