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Enzyme classification
EC, category 4.-.-.- lyases
Response type cleavage
Parent taxon Creature

Lyases are enzymes of the fourth class of enzymes , according to the systematic nomenclature of the enzyme commission of International Union of Biochemistry (IUB) and catalyze a cleavage of the molecule . Lyases occur in all living things. The reaction scheme:

Lyases produce a non- hydrolytic cleavage of a molecule into two products, usually with the formation of a double bond or a ring structure.


Lyases are categorized in the EC number classification system under EC  4.-.-.- . Thereafter, lyases are further subdivided depending on what type of bond is broken:

number binding example
EC  4.1.-.- CC bond Aldolase
EC  4.2.-.- CO binding Fumarase
EC  4.3.-.- CN bond Argininosuccinate lyase
EC  4.4.-.- CS bond Cystathionine β-lyase
EC  4.5.-.- C-halogen bond DDT dehydrochlorinase
EC  4.6.-.- PO bond Adenylyl cyclases
EC  4.7.-.- CP binding

Other classes of enzymes