Lyases are a group of enzymes which catalyze the removal or addition of elements including ammonia, water, or carbon dioxide. These catalyzed reactions eliminate the bond existing between two carbon atoms or the bond between a carbon atom and another (including sulfur or oxygen, for example). Lyases are typically present in cellular processes like organic synthesis or within the citric acid cycle. They are also present when cyanohydrins are produced. Oxynitrilase also catalyzes ketone; resulting from the production of cyanohydrin. In addition to this; fumarase is present when (S)-malic acid is produced via fumaric acid.
Lyases are structured into several different groups. Carbon-Carbon Lyases is a subclass of Lyases; this subclass is found to contain decarboxylases and oxo-acid lyases which are known to catalyze 3-hydroxy acid. Carbon-Halide bonds can work to utilize the removal of hydrochloric acid from dichloro-diphenyl-trichloroethane (a kind of synthetic pesticide). Then there is also a type referred to as Carbon-Sulfur Lyases; which can eradicate a reaction involving dihydrogen sulfide. A further subclass are Carbon-Oxygen Lyases; these are made up of hydro-lyases which catalyze the dissolution of C-O bonds; a process involving the elimination of water. C-O Lyases can further work to catalyze the eradication of a phosphate or alcohol from a polysaccharide. Carbon-Nitrogen Lyases, on the other hand, are those enzymes that release ammonia by forming a double bond. The Phosphorus-Oxygen form of Lyases, prevents the presence of nucleotide triphosphates in diphosphate.
Lyase is an enzyme which aids the breakdown of different chemical bonds. Lyase does so by an elimination reaction. Such an eradication and reaction can produce a double bond or a new cyclic structure. When creating a double bond (or a new ring) Lyase works upon a single substrate so that a molecule is eliminated. Just one substrate is needed for a reaction (which differs from other enzymes). For a reverse reaction however, two substrates are required. Lyases is present in glycolysis whereby aldolase could degrade fructose 1-6 bisphosphate into dihydroxyacetone phosphate. The former is an instance of Lyase serving a carbon-carbon bond. Aldolase, decarboxylase, and dehydratase are referred to as substrate group of Lyase.