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:

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.

1 Nomenclature
2 Classification
3 See also
4 References

[edit] 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.

[edit] 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
EC 4.99 includes other lyases