Cysteine metabolism refers to the biological pathways that consume or create cysteine. The pathways of different amino acids and other metabolites interweave and overlap to creating complex systems.
Sulfite oxidase is an enzyme in the mitochondria of all eukaryotes, with exception of the yeasts. It oxidizes sulfite to sulfate and, via cytochrome c, transfers the electrons produced to the electron transport chain, allowing generation of ATP in oxidative phosphorylation. This is the last step in the metabolism of sulfur-containing compounds and the sulfate is excreted.
Rhodanese, also known as rhodanase, thiosulfate sulfurtransferase, thiosulfate cyanide transsulfurase, and thiosulfate thiotransferase, is a mitochondrial enzyme that detoxifies cyanide (CN−) by converting it to thiocyanate (SCN−).
In enzymology, a 3-mercaptopyruvate sulfurtransferase is an enzyme that catalyzes the chemical reactions of 3-mercaptopyruvate. This enzyme belongs to the family of transferases, specifically the sulfurtransferases. This enzyme participates in cysteine metabolism. It is encoded by the MPST gene.
Biotin synthase (BioB) is an enzyme that catalyzes the conversion of dethiobiotin (DTB) to biotin; this is the final step in the biotin biosynthetic pathway. Biotin, also known as vitamin B7, is a cofactor used in carboxylation, decarboxylation, and transcarboxylation reactions in many organisms including humans. Biotin synthase is an S-Adenosylmethionine (SAM) dependent enzyme that employs a radical mechanism to thiolate dethiobiotin, thus converting it to biotin.
Lipoyl synthase is an enzyme that belongs to the radical SAM (S-adenosyl methionine) family. Within the radical SAM superfamily, lipoyl synthase is in a sub-family of enzymes that catalyze sulfur insertion reactions. The enzymes in this subfamily differ from general radical SAM enzymes, as they contain two 4Fe-4S clusters. From these clusters, the enzymes obtain the sulfur groups that will be transferred onto the corresponding substrates. This particular enzyme participates in the final step of lipoic acid metabolism, transferring two sulfur atoms from its 4Fe-4S cluster onto the protein N6-(octanoyl)lysine through radical generation. This enzyme is usually localized to the mitochondria. Two organisms that have been extensively studied with regards to this enzyme are Escherichia coli and Mycobacterium tuberculosis. It is currently being studied in other organisms including yeast, plants, and humans.
Molybdenum cofactor biosynthesis protein 1 is a protein that in humans and other animals, fungi, and cellular slime molds, is encoded by the MOCS1 gene.
Molybdenum cofactor synthesis protein 2A and molybdenum cofactor synthesis protein 2B are a pair of proteins that in humans are encoded from the same MOCS2 gene. These two proteins dimerize to form molybdopterin synthase.
Adenylyltransferase and sulfurtransferase MOCS3 is an enzyme that in humans is encoded by the MOCS3 gene.
Molybdopterin synthase (EC 2.8.1.12, MPT synthase) is an enzyme required to synthesize molybdopterin (MPT) from precursor Z (now known as cyclic pyranopterin monophosphate). Molydopterin is subsequently complexed with molybdenum to form molybdenum cofactor (MoCo). MPT synthase catalyses the following chemical reaction:
Radical SAM is a designation for a superfamily of enzymes that use a [4Fe-4S]+ cluster to reductively cleave S-adenosyl-L-methionine (SAM) to generate a radical, usually a 5′-deoxyadenosyl radical (5'-dAdo), as a critical intermediate. These enzymes utilize this radical intermediate to perform diverse transformations, often to functionalize unactivated C-H bonds. Radical SAM enzymes are involved in cofactor biosynthesis, enzyme activation, peptide modification, post-transcriptional and post-translational modifications, metalloprotein cluster formation, tRNA modification, lipid metabolism, biosynthesis of antibiotics and natural products etc. The vast majority of known radical SAM enzymes belong to the radical SAM superfamily, and have a cysteine-rich motif that matches or resembles CxxxCxxC. rSAMs comprise the largest superfamily of metal-containing enzymes.
Quinolinate synthase (EC 2.5.1.72, NadA, QS, quinolinate synthetase) is an enzyme with systematic name glycerone phosphate:iminosuccinate alkyltransferase (cyclizing). This enzyme catalyses the following chemical reaction
Lipoate–protein ligase (EC 2.7.7.63, LplA, lipoate protein ligase, lipoate–protein ligase A, LPL, LPL-B) is an enzyme with systematic name ATP:lipoate adenylyltransferase. This enzyme catalyses the following chemical reaction
Molybdenum cofactor cytidylyltransferase is an enzyme with systematic name CTP:molybdenum cofactor cytidylyltransferase. This enzyme catalyses the following chemical reaction:
Molybdenum cofactor guanylyltransferase is an enzyme with systematic name GTP:molybdenum cofactor guanylyltransferase. This enzyme catalyses the following chemical reaction:
Molybdopterin-synthase adenylyltransferase is an enzyme with systematic name ATP:molybdopterin-synthase adenylyltransferase. This enzyme catalyses the following chemical reaction
Molybdenum cofactor sulfurtransferase (EC 2.8.1.9, molybdenum cofactor sulfurase, ABA3, MoCo sulfurase, MoCo sulfurtransferase) is an enzyme with systematic name L-cysteine:molybdenum cofactor sulfurtransferase. This enzyme catalyses the following chemical reaction
Thiazole synthase (EC 2.8.1.10, thiG (gene)) is an enzyme with systematic name 1-deoxy-D-xylulose 5-phosphate:thiol sulfurtransferase. This enzyme catalyses the following chemical reaction
Molybdopterin molybdotransferase is an enzyme with systematic name adenylyl-molybdopterin:molybdate molybdate transferase (AMP-forming). This enzyme catalyses the following chemical reaction
Cyclic pyranopterin monophosphate synthase is an enzyme with systematic name GTP 8,9-lyase . This enzyme catalyses the following chemical reaction
