Accepted name: dihydroflavonol 4-reductase
Reaction: a (2R,3S,4S)-leucoanthocyanidin + NADP+ = a (2R,3R)-dihydroflavonol + NADPH + H+
Other name(s): dihydrokaempferol 4-reductase; dihydromyricetin reductase; NADPH-dihydromyricetin reductase; dihydroquercetin reductase; DFR (gene name); cis-3,4-leucopelargonidin:NADP+ 4-oxidoreductase; dihydroflavanol 4-reductase (incorrect)
Systematic name: (2R,3S,4S)-leucoanthocyanidin:NADP+ 4-oxidoreductase
Comments: This plant enzyme, involved in the biosynthesis of anthocyanidins, is known to act on (+)-dihydrokaempferol, (+)-taxifolin, and (+)-dihydromyricetin, although some enzymes may act only on a subset of these compounds. Each dihydroflavonol is reduced to the corresponding cis-flavan-3,4-diol. NAD+ can act instead of NADP+, but more slowly.
1.  Heller, W., Forkmann, G., Britsch, L. and Grisebach, H. Enzymatic reduction of (+)-dihydroflavonols to flavan-3,4-cis- diols with flower extracts from Matthiola incana and its role in anthocyanin biosynthesis. Planta 165 (1985) 284–287. [PMID: 24241054]
2.  Stafford, H.A. and Lester, H.H. Flavan-3-ol biosynthesis the conversion of (+)-dihydromyricetin to its flavan-3,4-diol (leucodelphinidin) and to (+)-gallocatechin by reductases extracted from tissue-cultures of Ginkgo biloba and Pseudotsuga-menziesii. Plant Physiol. 78 (1985) 791–794. [PMID: 16664326]
3.  Fischer, D., Stich, K., Britsch, L. and Grisebach, H. Purification and characterization of (+)dihydroflavonol (3-hydroxyflavanone) 4-reductase from flowers of Dahlia variabilis. Arch. Biochem. Biophys. 264 (1988) 40–47. [PMID: 3293532]
4.  Li, H., Qiu, J., Chen, F., Lv, X., Fu, C., Zhao, D., Hua, X. and Zhao, Q. Molecular characterization and expression analysis of dihydroflavonol 4-reductase (DFR) gene in Saussurea medusa. Mol. Biol. Rep. 39 (2012) 2991–2999. [PMID: 21701830]
[EC created 1989, modified 2016]
Accepted name: anthocyanidin reductase [(2R,3R)-flavan-3-ol-forming]
Reaction: a (2R,3R)-flavan-3-ol + 2 NAD(P)+ = an anthocyanidin with a 3-hydroxy group + 2 NAD(P)H + H+
Other name(s): ANR (gene name) (ambiguous); flavan-3-ol:NAD(P)+ oxidoreductase; anthocyanidin reductase (ambiguous)
Systematic name: (2R,3R)-flavan-3-ol:NAD(P)+ 3,4-oxidoreductase
Comments: The enzyme participates in the flavonoid biosynthesis pathway found in plants. It catalyses the double reduction of anthocyanidins, producing (2R,3R)-flavan-3-ol monomers required for the formation of proanthocyanidins. While the enzyme from the legume Medicago truncatula (MtANR) can use both NADPH and NADH as reductant, that from the crucifer Arabidopsis thaliana (AtANR) uses only NADPH. Also, while the substrate preference of MtANR is cyanidin>pelargonidin>delphinidin, the reverse preference is found with AtANR. cf. EC, anthocyanidin reductase [(2S)-flavan-3-ol-forming].
1.  Xie, D.Y., Sharma, S.B., Paiva, N.L., Ferreira, D. and Dixon, R.A. Role of anthocyanidin reductase, encoded by BANYULS in plant flavonoid biosynthesis. Science 299 (2003) 396–399. [PMID: 12532018]
2.  Xie, D.Y., Sharma, S.B. and Dixon, R.A. Anthocyanidin reductases from Medicago truncatula and Arabidopsis thaliana. Arch. Biochem. Biophys. 422 (2004) 91–102. [PMID: 14725861]
3.  Pang, Y., Abeysinghe, I.S., He, J., He, X., Huhman, D., Mewan, K.M., Sumner, L.W., Yun, J. and Dixon, R.A. Functional characterization of proanthocyanidin pathway enzymes from tea and their application for metabolic engineering. Plant Physiol. 161 (2013) 1103–1116. [PMID: 23288883]
[EC created 2004, modified 2016]
Accepted name: leucoanthocyanidin reductase
Reaction: (2R,3S)-catechin + NADP+ + H2O = 2,3-trans-3,4-cis-leucocyanidin + NADPH + H+
Other name(s): leucocyanidin reductase
Systematic name: (2R,3S)-catechin:NADP+ 4-oxidoreductase
Comments: The enzyme catalyses the synthesis of catechin, catechin-4β-ol (leucocyanidin) and the related flavan-3-ols afzelechin and gallocatechin, which are initiating monomers in the synthesis of plant polymeric proanthocyanidins or condensed tannins. While 2,3-trans-3,4-cis-leucocyanidin is the preferred flavan-3,4-diol substrate, 2,3-trans-3,4-cis-leucodelphinidin and 2,3-trans-3,4-cis-leucopelargonidin can also act as substrates, but more slowly. NADH can replace NADPH but is oxidized more slowly.
1.  Tanner, G.J. and Kristiansen, K.N. Synthesis of 3,4-cis-[3H]leucocyanidin and enzymatic reduction to catechin. Anal. Biochem. 209 (1993) 274–277. [PMID: 8470799]
2.  Tanner, G.J., Francki, K.T., Abrahams, S., Watson, J.M., Larkin, P.J. and Ashton, A.R. Proanthocyanidin biosynthesis in plants: Purification of legume leucoanthocyanidin reductase and molecular cloning of its cDNA. J. Biol. Chem. 278 (2003) 31647–31656. [PMID: 12788945]
[EC created 2003]
Accepted name: flavonoid 3′,5′-methyltransferase
Reaction: (1) S-adenosyl-L-methionine + a 3′-hydroxyflavonoid = S-adenosyl-L-homocysteine + a 3′-methoxyflavonoid
(2) S-adenosyl-L-methionine + a 5′-hydroxy-3′-methoxyflavonoid = S-adenosyl-L-homocysteine + a 3′,5′-dimethoxyflavonoid
Glossary: delphinidin = 3,3′,4′,5,5′,7-hexahydroxyflavylium
cyanidin = 3,3′,4′,5,7-pentahydroxyflavylium
myricetin = 3,3′,4′,5,5′,7-hexahydroxyflavone
quercetin = 3,3′,4′,5,7-pentahydroxyflavone
Other name(s): AOMT; CrOMT2
Systematic name: S-adenosyl-L-methionine:flavonoid 3′-O-methyltransferase
Comments: Isolated from Vitis vinifera (grape) [2]. Most active with delphinidin 3-glucoside but also acts on cyanidin 3-glucoside, cyanidin, myricetin, quercetin and quercetin 3-glucoside. The enzyme from Catharanthus roseus was most active with myricetin [1].
1.  Cacace, S., Schröder, G., Wehinger, E., Strack, D., Schmidt, J. and Schröder, J. A flavonol O-methyltransferase from Catharanthus roseus performing two sequential methylations. Phytochemistry 62 (2003) 127–137. [PMID: 12482447]
2.  Hugueney, P., Provenzano, S., Verries, C., Ferrandino, A., Meudec, E., Batelli, G., Merdinoglu, D., Cheynier, V., Schubert, A. and Ageorges, A. A novel cation-dependent O-methyltransferase involved in anthocyanin methylation in grapevine. Plant Physiol. 150 (2009) 2057–2070. [PMID: 19525322]
[EC created 2013, modified 2014]
Accepted name: anthocyanin 6′′-O-malonyltransferase
Reaction: malonyl-CoA + an anthocyanidin 3-O-β-D-glucoside = CoA + an anthocyanidin 3-O-(6-O-malonyl-β-D-glucoside)
Systematic name: malonyl-CoA:anthocyanidin-3-O-β-D-glucoside 6′′-O-malonyltransferase
Comments: Acts on pelargonidin 3-O-glucoside in dahlia (Dahlia variabilis), delphinidin 3-O-glucoside, and on cyanidin 3-O-glucoside in transgenic petunia (Petunia hybrida).
1.  Suzuki, H., Nakayama, T., Yonekura-Sakakibara, K., Fukui, Y., Nakamura, N., Yamaguchi, M.A., Tanaka, Y., Kusumi, T. and Nishino, T. cDNA cloning, heterologous expressions, and functional characterization of malonyl-coenzyme A:anthocyanidin 3-O-glucoside-6′′-O-malonyltransferase from dahlia flowers. Plant Physiol. 130 (2002) 2142–2151. [PMID: 12481098]
[EC created 2004]
Accepted name: anthocyanin 5-O-glucoside 6′′′-O-malonyltransferase
Reaction: malonyl-CoA + pelargonidin 3-O-(6-caffeoyl-β-D-glucoside) 5-O-β-D-glucoside = CoA + 4′′′-demalonylsalvianin
Glossary: salvianin = pelargonidin 3-O-(6-caffeoyl-β-D-glucoside) 5-O-(4,6-di-O-malonyl-β-D-glucoside)
4′′′-demalonylsalvianin = pelargonidin 3-O-(6-caffeoyl-β-D-glucoside) 5-O-(6-O-malonyl-β-D-glucoside)
pelargonidin = 3,4′,5,7-tetrahydroxyflavylium
Systematic name: malonyl-CoA:pelargonidin-3-O-(6-caffeoyl-β-D-glucoside)-5-O-β-D-glucoside 6′′′-O-malonyltransferase
Comments: Specific for the penultimate step in salvianin biosynthesis. The enzyme also catalyses the malonylation of shisonin to malonylshisonin [cyanidin 3-O-(6′′-O-p-coumaryl-β-D-glucoside)-5-(6′′′-O-malonyl-β-D-glucoside)]. The compounds 4′′′-demalonylsalvianin, salvianin, pelargonidin 3,5-diglucoside and delphinidin 3,5-diglucoside cannot act as substrates.
1.  Suzuki, H., Nakayama, T., Yonekura-Sakakibara, K., Fukui, Y., Nakamura, N., Nakao, M., Tanaka, Y., Yamaguchi, M.A., Kusumi, T. and Nishino, T. Malonyl-CoA:anthocyanin 5-O-glucoside-6′′′-O-malonyltransferase from scarlet sage (Salvia splendens) flowers. J. Biol. Chem. 276 (2001) 49013–49019. [PMID: 11598135]
[EC created 2004]
Accepted name: anthocyanidin 3-O-glucoside 6′′-O-acyltransferase
Reaction: 4-hydroxycinnamoyl-CoA + an anthocyanidin 3-O-β-D-glucoside = CoA + an anthocyanidin 3-O-[6-O-(4-hydroxycinnamoyl)-β-D-glucoside]
Glossary: 4-hydroxycinnamoyl-CoA = 4-coumaroyl-CoA
3,4-dihydroxycinnamoyl-CoA = caffeoyl-CoA
cyanidin = 3,3′,4′,5,7-pentahydroxyflavylium
delphinidin = 3,3′,4′,5,5′,7-hexahydroxyflavylium
Systematic name: 4-hydroxycinnamoyl-CoA:anthocyanin-3-O-glucoside 6′′-O-acyltransferase
Comments: Isolated from the plants Perilla frutescens and Gentiana triflora (clustered gentian). Acts on a range of anthocyanidin 3-O-glucosides, 3,5-di-O-glucosides and cyanidin 3-rutinoside. It did not act on delphinidin 3,3′,7-tri-O-glucoside. Recombinant Perilla frutescens enzyme could utilize caffeoyl-CoA but not malonyl-CoA as alternative acyl donor.
1.  Fujiwara, H., Tanaka, Y., Fukui, Y., Ashikari, T., Yamaguchi, M. and Kusumi, T. Purification and characterization of anthocyanin 3-aromatic acyltransferase from Perilla frutescens. Plant Sci. 137 (1998) 87–94.
2.  Yonekura-Sakakibara, K., Tanaka, Y., Fukuchi-Mizutani, M., Fujiwara, H., Fukui, Y., Ashikari, T., Murakami, Y., Yamaguchi, M. and Kusumi, T. Molecular and biochemical characterization of a novel hydroxycinnamoyl-CoA: anthocyanin 3-O-glucoside-6"-O-acyltransferase from Perilla frutescens. Plant Cell Physiol. 41 (2000) 495–502. [PMID: 10845463]
[EC created 2013]
Accepted name: anthocyanidin 3-O-glucosyltransferase
Reaction: UDP-D-glucose + an anthocyanidin = UDP + an anthocyanidin-3-O-β-D-glucoside
Other name(s): uridine diphosphoglucose-anthocyanidin 3-O-glucosyltransferase; UDP-glucose:anthocyanidin/flavonol 3-O-glucosyltransferase; UDP-glucose:cyanidin-3-O-glucosyltransferase; UDP-glucose:anthocyanidin 3-O-D-glucosyltransferase; 3-GT
Systematic name: UDP-D-glucose:anthocyanidin 3-O-β-D-glucosyltransferase
Comments: The anthocyanidin compounds cyanidin, delphinidin, peonidin and to a lesser extent pelargonidin can act as substrates. The enzyme does not catalyse glucosylation of the 5-position of cyanidin and does not act on flavanols such as quercetin and kaempferol (cf. EC flavonol 3-O-glucosyltransferase). In conjunction with EC, anthocyanidin oxygenase, it is involved in the conversion of leucoanthocyanidin into anthocyanidin 3-glucoside. It may act on the pseudobase precursor of the anthocyanidin rather than on the anthocyanidin itself [3].
1.  Kamsteeg, J., van Brederode, J. and van Nigtevecht, G. Identification and properties of UDP-glucose: cyanidin-3-O-glucosyltransferase isolated from petals of the red campion (Silene dioica). Biochem. Genet. 16 (1978) 1045–1058. [PMID: 751640]
2.  Ford, C.M., Boss, P.K. and Høj, P.B. Cloning and characterization of Vitis vinifera UDP-glucose:flavonoid 3-O-glucosyltransferase, a homologue of the enzyme encoded by the maize Bronze-1 locus that may primarily serve to glucosylate anthocyanidins in vivo. J. Biol. Chem. 273 (1998) 9224–9233. [PMID: 9535914]
3.  Nakajima, J., Tanaka, Y., Yamazaki, M. and Saito, K. Reaction mechanism from leucoanthocyanidin to anthocyanidin 3-glucoside, a key reaction for coloring in anthocyanin biosynthesis. J. Biol. Chem. 276 (2001) 25797–25803. [PMID: 11316805]
[EC created 1984 (EC created 2004, incorporated 2005), modified 2005]
Accepted name: cyanidin 3-O-rutinoside 5-O-glucosyltransferase
Reaction: UDP-α-D-glucose + cyanidin-3-O-rutinoside = UDP + cyanidin 3-O-rutinoside 5-O-β-D-glucoside
Glossary: cyanidin 3-O-rutinoside = cyanidin-3-O-α-L-rhamnosyl-(1→6)-β-D-glucoside
cyanidin = 3,3′,4′,5,7-pentahydroxyflavylium
Other name(s): uridine diphosphoglucose-cyanidin 3-rhamnosylglucoside 5-O-glucosyltransferase; cyanidin-3-rhamnosylglucoside 5-O-glucosyltransferase; UDP-glucose:cyanidin-3-O-D-rhamnosyl-1,6-D-glucoside 5-O-D-glucosyltransferase
Systematic name: UDP-α-D-glucose:cyanidin-3-O-α-L-rhamnosyl-(1→6)-β-D-glucoside 5-O-β-D-glucosyltransferase
Comments: Isolated from the plants Silene dioica (red campion) [1], Iris ensata (Japanese iris) [2] and Iris hollandica (Dutch iris) [3]. Also acts on the 3-O-rutinosides of pelargonidin, delphinidin and malvidin, but not the corresponding glucosides or 6-acylglucosides. The enzyme does not catalyse the glucosylation of the 5-hydroxy group of cyanidin 3-glucoside.
1.  Kamsteeg, J., van Brederode, J. and van Nigtevecht, G. Identification, properties, and genetic control of UDP-glucose: cyanidin-3-rhamnosyl-(1→6)-glucoside-5-O-glucosyltransferase isolated from petals of the red campion (Silene dioica). Biochem. Genet. 16 (1978) 1059–1071. [PMID: 751641]
2.  Yabuya, T., Yamaguchi, M., Imayama, T., Katoh, K. and Ino I. Anthocyanin 5-O-glucosyltransferase in flowers of Iris ensata. Plant Sci. 162 (2002) 779–784.
3.  Imayama, T., Yoshihara, Y., Fukuchi-Mizutani, M., Tanaka, Y., Ino, I. and Yabuya, T. Isolation and characterization of a cDNA clone of UDP-glucose:anthocyanin 5-O-glucosyltransferase in Iris hollandica. Plant Sci. 167 (2004) 1243–1248.
[EC created 1984 (EC created 2004, incorporated 2006), modified 2006, modified 2013]
Accepted name: delphinidin 3,5-di-O-glucoside 3′-O-glucosyltransferase
Reaction: UDP-α-D-glucose + delphinidin 3,5-di-O-β-D-glucoside = UDP + delphinidin 3,3′,5-tri-O-β-D-glucoside
Glossary: delphinidin = 3,3′,4′,5,5′,7-hexahydroxyflavylium
Other name(s): UDP-glucose:anthocyanin 3′-O-glucosyltransferase; 3’GT
Systematic name: UDP-α-D-glucose:delphinidin-3,5-di-O-β-D-glucoside 3′-O-glucosyltransferase
Comments: Isolated from the plant Gentiana triflora (clustered gentian).
1.  Fukuchi-Mizutani, M., Okuhara, H., Fukui, Y., Nakao, M., Katsumoto, Y., Yonekura-Sakakibara, K., Kusumi, T., Hase, T. and Tanaka, Y. Biochemical and molecular characterization of a novel UDP-glucose:anthocyanin 3′-O-glucosyltransferase, a key enzyme for blue anthocyanin biosynthesis, from gentian. Plant Physiol. 132 (2003) 1652–1663. [PMID: 12857844]
[EC created 2004, modified 2013]
Accepted name: delphinidin 3′,5′-O-glucosyltransferase
Reaction: 2 UDP-glucose + delphinidin 3-O-(6′′-O-malonyl)-β-D-glucoside = 2 UDP + delphinidin 3-O-(6′′-O-malonyl)-β-D-glucoside-3′,5′-di-O-β-D-glucoside (overall reaction)
(1a) UDP-glucose + delphinidin 3-O-(6′′-O-malonyl)-β-D-glucoside = UDP + delphinidin 3-O-(6′′-O-malonyl)-β-D-glucoside-3′-O-β-D-glucoside
(1b) UDP-glucose + delphinidin 3-O-(6′′-O-malonyl)-β-D-glucoside-3′-O-β-D-glucoside = UDP + delphinidin 3-O-(6′′-O-malonyl)-β-D-glucoside-3′,5′-di-O-β-D-glucoside
Glossary: delphinidin 3-O-(6′′-O-malonyl)-β-D-glucoside-3′,5′-di-O-β-D-glucoside = ternatin C5
Other name(s): UDP-glucose:anthocyanin 3′,5′-O-glucosyltransferase; UA3′5’GZ
Systematic name: UDP-glucose:delphinidin 3-O-(6′′-O-malonyl)-β-D-glucoside 3′-O-glucosyltransferase
Comments: Ternatins are a group of polyacetylated delphinidin glucosides that confer blue color to the petals of Clitoria ternatea (butterfly pea). This enzyme catalyses two reactions in the biosynthesis of ternatin C5: the conversion of delphinidin 3-O-(6′′-O-malonyl)-β-D-glucoside to delphinidin 3-O-(6′′-O-malonyl)-β-D-glucoside-3′-O-β-D-glucoside, followed by the conversion of the later to ternatin C5, by transferring two glucosyl groups in a stepwise manner [1].
1.  Kogawa, K., Kato, N., Kazuma, K., Noda, N. and Suzuki, M. Purification and characterization of UDP-glucose: anthocyanin 3′,5′-O-glucosyltransferase from Clitoria ternatea. Planta 226 (2007) 1501–1509. [PMID: 17668234]
[EC created 2009]
Accepted name: anthocyanidin 3-O-glucoside 2′′′-O-xylosyltransferase
Reaction: UDP-α-D-xylose + an anthocyanidin 3-O-β-D-glucoside = UDP + an anthocyanidin 3-O-β-D-sambubioside
Glossary: anthocyanidin 3-O-β-D-sambubioside = anthocyanidin 3-O-(β-D-xylosyl-(1→2)-β-D-glucoside)
Other name(s): uridine 5′-diphosphate-xylose:anthocyanidin 3-O-glucose-xylosyltransferase; UGT79B1
Systematic name: UDP-α-D-xylose:anthocyanidin-3-O-β-D-glucoside 2′′′-O-xylosyltransferase
Comments: Isolated from the plants Matthiola incana (stock) [1] and Arabidopsis thaliana (mouse-eared cress) [2]. The enzyme has similar activity with the 3-glucosides of pelargonidin, cyanidin, delphinidin, quercetin and kaempferol as well as with cyanidin 3-O-rhamnosyl-(1→6)-glucoside and cyanidin 3-O-(6-acylglucoside). There is no activity with other UDP-sugars or with cyanidin 3,5-diglucoside.
1.  Teusch, M. Uridine 5′-diphosphate-xylose:anthocyanidin 3-O-glucose-xylosyltransferase from petals of Matthiola incana R.Br. Planta 169 (1986) 559–563. [PMID: 24232765]
2.  Yonekura-Sakakibara, K., Fukushima, A., Nakabayashi, R., Hanada, K., Matsuda, F., Sugawara, S., Inoue, E., Kuromori, T., Ito, T., Shinozaki, K., Wangwattana, B., Yamazaki, M. and Saito, K. Two glycosyltransferases involved in anthocyanin modification delineated by transcriptome independent component analysis in Arabidopsis thaliana. Plant J. 69 (2012) 154–167. [PMID: 21899608]
[EC created 2013]