Stizolobate synthase

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Stizolobate synthase
Identifiers
EC no. 1.13.11.29
CAS no. 65979-39-7
Databases
IntEnz IntEnz view
BRENDA BRENDA entry
ExPASy NiceZyme view
KEGG KEGG entry
MetaCyc metabolic pathway
PRIAM profile
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Gene Ontology AmiGO / QuickGO
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Stizolobate synthase (EC 1.13.11.29) is an enzyme that catalyzes the chemical reaction

 
O2
 
Stizolobate synthase
 
 
 

The two substrates of this enzyme are L-DOPA and oxygen. Its initial product is 4-(L-alanin-3-yl)-2-hydroxy-cis,cis-muconate 6-semialdehyde. [1]

The intermediate readily cyclises and further oxidises, forming a 2-pyrone ring; this stizolobic acid, which is the product that is isolated and after which this enzyme is named. [2] [3]

4-(L-alanin-3-yl)-2-hydroxy-cis,cis-muconate 6-semialdehyde.svg
intermediate
+ NAD+
 
 
 
 
Stizolobate synthase
 
 
 
+ NADH
 

The oxidation step uses oxidised nicotinamide adenine dinucleotide as a cofactor and the enzyme also requires zinc. It belongs to the family of oxidoreductases, specifically those acting on single donors with O2 as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O2. The systematic name of this enzyme class is 3,4-dihydroxy-L-phenylalanine:oxygen 4,5-oxidoreductase (recyclizing). It participates in tyrosine metabolism. [1]

Stizolobinic acid Stizolobinic acid.svg
Stizolobinic acid

A separate enzyme, stizolobinate synthase also present in the plant cleaves L-DOPA in an way which produces the isomeric compound, stizolobinic acid. [3]

References

  1. 1 2 Enzyme 1.13.11.29 at KEGG Pathway Database.
  2. Saito K, Komamine A (1976). "Biosynthesis of stizolobinic acid and stizolobic acid in higher plants. An enzyme system(s) catalyzing the conversion of dihydroxyphenylalanine into stizolobinic acid and stizolobic acid from etiolated seedlings of Stizolobium hassjoo". Eur. J. Biochem. 68 (1): 237–43. doi:10.1111/j.1432-1033.1976.tb10783.x. PMID   9285.
  3. 1 2 Saito K, Komamine A (1978). "Biosynthesis of stizolobinic acid and stizolobic acid in higher plants". Eur. J. Biochem. 82 (2): 385–92. doi: 10.1111/j.1432-1033.1978.tb12033.x . PMID   624278.