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:

:ATP → cAMP + PPi

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.


Systematic names are formed as "substrate group" lysase." 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:
* 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)
* includes lyases that cleave carbon-oxygen bonds, such as dehydratases
* includes lyases that cleave carbon-nitrogen bonds
* includes lyases that cleave carbon-sulfur bonds
* includes lyases that cleave carbon-halide bonds
* includes lyases that cleave phosphorus-oxygen bonds, such as adenylate cyclase and guanylate cyclase
* includes other lyases, such as ferrochelatase

ee also

* List of EC numbers of enzymes belonging to category EC 4


* [ EC 4 Introduction] from the Department of Chemistry at Queen Mary, University of London

Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Lyase — ist in der Biochemie der Oberbegriff für alle Enzyme, die eine Molekülspaltung katalysieren. Beispiel: A–B → A + B Sie haben die EC Nummer EC 4. Synthasen, welches ebenfalls Lyasen sind, katalysieren die Synthese komplexerer Produkte aus… …   Deutsch Wikipedia

  • lyase — [lī′ās΄, lī′āz΄] n. any of a class of enzymes that act as catalysts in chemical reactions involving double bonds …   English World dictionary

  • Lyase — En biochimie, une lyase est une enzyme qui catalyse la rupture de différentes liaisons chimiques par des moyens autres que l hydrolyse ou l oxydation, formant ainsi souvent une nouvelle liaison double ou un nouveau cycle. Par exemple une enzyme… …   Wikipédia en Français

  • lyase — liazė statusas T sritis chemija apibrėžtis Fermentas, katalizuojantis atomų arba grupių prisijungimo prie dvigubųjų ryšių arba atvirkštines reakcijas. atitikmenys: angl. lyase rus. лиаза …   Chemijos terminų aiškinamasis žodynas

  • lyase — noun Date: 1961 an enzyme (as a decarboxylase) that forms double bonds by removing groups from a substrate other than by hydrolysis or that adds groups to double bonds …   New Collegiate Dictionary

  • lyase — /luy ays, ayz/, n. Biochem. any of various enzymes, as decarboxylase, that catalyze reactions involving the formation of or addition to a double bond. [1960 65; < Gk lý(ein) to loosen, dissolve (see LYSIS) + ASE] * * *       in physiology, any… …   Universalium

  • lyase — noun Any of many classes of enzyme that catalyze the breaking of a specific form of bond …   Wiktionary

  • lyase — Class name for those enzymes removing groups nonhydrolytically (EC class 4); prefixes such as “hydro ” and “ammonia ” are used to indicate the type of reaction. Trivial names for lyases include synthases, decarboxylases, aldolases, dehydratases.… …   Medical dictionary

  • Lyase — Ly|a|se 〈f. 19; Biochem.〉 Enzym, das organische Verbindungen in Bruchstücke spaltet [zu grch. lyein „lösen“] * * * Ly|a|se [griech. lýein = lösen, auflösen, trennen, befreien; ↑ ase], die; , n: nicht empfohlenes Syn.: Synthase: Gruppenbez. für… …   Universal-Lexikon

  • Lyase — Ly|a|se 〈f.; Gen.: , Pl.: n; Biochemie〉 Enzym, das organische Verbindungen in Bruchstücke spaltet [Etym.: <grch. lyein »lösen«] …   Lexikalische Deutsches Wörterbuch