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ENZYME entry: EC

Accepted Name
poly[(R)-3-hydroxyalkanoate] polymerase
Alternative Name(s)
PHA synthase
Reaction catalysed
[(R)-3-hydroxyalkanoate](n) + a (3R)-3-hydroxyacyl-CoA <=> [(R)-3-hydroxyalkanoate](n+1) + CoA
  • This is the key enzyme in the biosynthesis of polyhydroxyalkanoates (PHA), linear polyesters produced by bacteria as a means of carbon and energy storage.
  • The enzyme catalyzes the stereoselective, covalent linkage of (3R)-3- hydroxyacyl-CoA thioesters in a transesterification reaction with concomitant release of coenzyme A.
  • The growing polymer is attached to a conserved active site L-cysteine residue.
  • Three types of PHA synthases have been proposed based on their substrate specificity and enzyme structure.
  • Type I and type III synthases preferentially polymerize short chain hydroxyalkanoate monomers containing 3-5 carbon atoms.
  • The difference between these two types is that type I synthases are composed of only a single subunit (PhaC), whereas type III synthases are composed of two different subunits, PhaC and PhaE. Type II synthases are also composed of a single subunit (PhaC), but preferentially polymerize monomers containing more than 5 carbon atoms.
PRIAM enzyme-specific profiles2.3.1.304
KEGG Ligand Database for Enzyme Nomenclature2.3.1.304
IUBMB Enzyme Nomenclature2.3.1.304
MEDLINEFind literature relating to
Rhea expert-curated reactions2.3.1.304

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