1.3.1.112: anthocyanidin reductase [(2S)-flavan-3-ol-forming]
This is an abbreviated version!
For detailed information about anthocyanidin reductase [(2S)-flavan-3-ol-forming], go to the full flat file.
Reaction
Synonyms
ANR, anthocyanidin reductase ((2S)-flavan-3-ol-forming)
ECTree
1.3.1.112 anthocyanidin reductase [(2S)-flavan-3-ol-forming]Advanced search results
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Substrates Products on EC 1.3.1.112 - anthocyanidin reductase [(2S)-flavan-3-ol-forming]
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SUBSTRATE 
PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate)
(Substrate)
LITERATURE
(Substrate)
(Substrate)
COMMENTARY
(Product)
(Product)
LITERATURE
(Product)
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
2 delphinidin + 4 NADPH + 4 H+
(-)-gallocatechin + (+)-epigallocatechin + 4 NADP+
-
-
-
ir
2 pelargonidin + 4 NADPH + 4 H+
(-)-afzelechin + (+)-epiafzelechin + 4 NADP+
-
-
-
ir
peonidin + 2 NADPH + 2 H+
(2S,3S)-3,5,7-trihydroxy-2-(4-hydroxy-3-methoxyphenyl)-2,3-dihydro-1-benzopyran-1-ium + 2 NADP+
-
-
-
?
2 cyanidin + 4 NADPH + 4 H+
(+)-epicatechin + (-)-catechin + 4 NADP+
-
-
-
?
2 cyanidin + 4 NADPH + 4 H+
(+)-epicatechin + (-)-catechin + 4 NADP+
-
at pH 7.5 and 30°C, the first hydride transfer to anthocyanidin is irreversible, and no intermediate is released during catalysis
-
ir
2 cyanidin + 4 NADPH + 4 H+
(+)-epicatechin + (-)-catechin + 4 NADP+
-
the relative concentration of catechin versus epicatechin remains nearly constant and is close to 1
-
?
additional information
?
-
ANR is strictly pro-S stereospecific and the reaction mechanism involves two hydride transfers from two distinct NADPH molecules. ANR produces a 50:50 mixture of 2,3-cis and 2,3-trans flavan-3-ols, i.e. 2S,3S- and 2S,3R-flavan-3-ols
-
-
?
additional information
?
-
hyperbolic and rapid-equilibrium ordered mechanism, with NADPH binding first. The most likely mechanism is sequential ordered Bi Uni Uni Bi, with NADPH binding first and NADP+ released last, and internal conversion of the first ternary complex, i.e. that associated with the first hydride transfer, is rate-limiting
-
-
?
additional information
?
-
in the presence of excess NADP+, ANR acts as a flavan-3-ol C3-epimerase, but only with 2R-flavan-3-ols, not with 2S-flavan-3-ols produced by the enzyme in the forward reaction. C3-epimerization should be achieved by tautomerization between the two hydride transfers and this produces a quinone methide intermediate which serves as C4 target of the second hydride transfer, avoiding any stereospecific modification of carbon 3. The inversion of C2 stereochemistry required for reverse epimerization suggests that the 2S configuration induces an irreversible product dissociation
-
-
?
