biochemistry, a lyase is an enzyme that catalyzes the breaking of various chemical bonds by means other than hydrolysis and oxidation, often forming a new double bond or a new ring structure. For example, an enzyme that catalyzed this reaction would be a lyase:
ATP → cAMP + PP i
Lyases differ from other enzymes in that they only require one
substrate for the reaction in one direction, but two substrates for the reverse reaction.
Additional recommended knowledge
Systematic names are formed as "
substrate group lyase." Common names include decarboxylase, dehydratase, aldolase, etc. When the reverse reaction is more important, synthase may be used in the name.
Lysases are classified as
EC 4 in the EC number classification of enzymes. Lyases can be further classified into seven subclasses:
EC 4.1 includes lyases that cleave carbon-carbon bonds, such as decarboxylases (EC 4.1.1), aldehyde lyases (EC 4.1.2), oxo acid lyases(EC 4.1.3) and others (EC 4.1.99)
EC 4.2 includes lyases that cleave carbon-oxygen bonds, such as dehydratases
EC 4.3 includes lyases that cleave carbon-nitrogen bonds
EC 4.4 includes lyases that cleave carbon-sulfur bonds
EC 4.5 includes lyases that cleave carbon-halide bonds
EC 4.6 includes lyases that cleave phosphorus-oxygen bonds, such as adenylate cyclase and guanylate cyclase
EC 4.99 includes other lyases, such as ferrochelatase
EC 4 Introduction from the Department of Chemistry at Queen Mary, University of London
Carbon-carbon lyases ( EC 4.1) 4.1.1: Carboxy-lyases Pyruvate decarboxylase -Oxaloacetate decarboxylase - Acetoacetate decarboxylase - Malonyl-CoA decarboxylase - Glutamate decarboxylase - Ornithine decarboxylase - Lysine decarboxylase - Phosphoribosylaminoimidazole carboxylase - Histidine decarboxylase - Uridine monophosphate synthetase/Orotidine 5'-phosphate decarboxylase - Aromatic L-amino acid decarboxylase - Phosphoenolpyruvate carboxylase - Pyrophosphomevalonate decarboxylase - Uroporphyrinogen III decarboxylase - RuBisCO - Phosphoenolpyruvate carboxykinase - Adenosylmethionine decarboxylase 4.1.2: Aldehyde-lyases Aldolase A/Aldolase B - 2-hydroxyphytanoyl-CoA lyase 4.1.3: Oxo-acid-lyases 3-hydroxy-3-methylglutaryl-CoA lyase
Carbon-oxygen lyases ( EC 4.2) (primarily dehydratases) Carbonic anhydrase - Fumarase - Aconitase - Enolase (Alpha) - Enoyl-CoA hydratase/3-Hydroxyacyl ACP dehydrase - Methylglutaconyl-CoA hydratase - Tryptophan synthase - Cystathionine beta synthase - Porphobilinogen synthase - 3-isopropylmalate dehydratase - Urocanate hydratase - Uroporphyrinogen III synthase - Nitrile hydratase
Carbon-nitrogen lyases ( EC 4.3) 4.3.1 - ammonia-lyases Histidine ammonia-lyase - Formiminotransferase cyclodeaminase - Serine dehydratase 4.3.2 - amidine-lyases Argininosuccinate lyase - Adenylosuccinate lyase
Carbon-sulfur lyases ( EC 4.4) Cystathionine gamma-lyase - Cystathionine-beta-lyase - Leukotriene C4 synthase
Carbon-halide lyases ( EC 4.5) Dichloromethane dehalogenase - Halohydrin dehalogenase