Lyase
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In 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:
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.
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Nomenclature
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.
Classification
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
See also
References
- EC 4 Introduction from the Department of Chemistry at Queen Mary, University of London
Proteins: enzymes | |
|---|---|
| Topics | Active site - Allosteric regulation - Binding site - Catalytically perfect enzyme - Coenzyme - Cofactor - Cooperativity - EC number Enzyme catalysis - Enzyme inhibitor - Enzyme kinetics - Lineweaver-Burk plot - Michaelis-Menten kinetics - List of enzymes |
| Types | EC1 Oxidoreductases/list - EC2 Transferases/list - EC3 Hydrolases/list - EC4 Lyases/list - EC5 Isomerases/list - EC6 Ligases/list |
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 |
Phosphorus-oxygen lyases (EC 4.6) |
|---|
| Adenylate cyclase - Guanylate cyclase (2D, c) |
bg:Лиаза cs:Lyasa de:Lyasen fr:Lyase it:Liasi ja:リアーゼ
Acknowledgement and Attribution Regarding Sources of Content
Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .
