The Enzyme Database

Nomenclature Committee of the International Union of Biochemistry and Molecular Biology (NC-IUBMB)

Proposed Changes to the Enzyme List

The entries below are proposed additions and amendments to the Enzyme Nomenclature list. They were prepared for the NC-IUBMB by Kristian Axelsen, Richard Cammack, Ron Caspi, Masaaki Kotera, Andrew McDonald, Gerry Moss, Dietmar Schomburg, Ida Schomburg and Keith Tipton. Comments and suggestions on these draft entries should be sent to Dr Andrew McDonald (Department of Biochemistry, Trinity College Dublin, Dublin 2, Ireland). The date on which an enzyme will be made official is appended after the EC number. To prevent confusion please do not quote new EC numbers until they are incorporated into the main list.

An asterisk before 'EC' indicates that this is an amendment to an existing enzyme rather than a new enzyme entry.


Contents

EC 1.1.1.295 momilactone-A synthase
EC 1.3.7.6 phycoerythrobilin synthase
EC 1.3.99.24 2-amino-4-deoxychorismate dehydrogenase
EC 2.3.1.185 tropine acyltransferase
EC 2.3.1.186 pseudotropine acyltransferase
EC 2.6.1.86 2-amino-4-deoxychorismate synthase
EC 2.7.1.161 CTP-dependent riboflavin kinase
EC 2.7.1.162 N-acetylhexosamine 1-kinase
EC 3.2.1.165 exo-1,4-β-D-glucosaminidase
EC 4.2.3.28 ent-cassa-12,15-diene synthase
EC 4.2.3.29 ent-sandaracopimaradiene synthase
EC 4.2.3.30 ent-pimara-8(14),15-diene synthase
EC 4.2.3.31 ent-pimara-9(11),15-diene synthase
EC 4.2.3.32 levopimaradiene synthase
EC 4.2.3.33 stemar-13-ene synthase
EC 4.2.3.34 stemod-13(17)-ene synthase
EC 4.2.3.35 syn-pimara-7,15-diene synthase
EC 5.5.1.14 syn-copalyl-diphosphate synthase


EC 1.1.1.295
Accepted name: momilactone-A synthase
Reaction: 3β-hydroxy-9β-pimara-7,15-diene-19,6β-olide + NAD(P)+ = momilactone A + NAD(P)H + H+
For diagram of the biosynthesis of diterpenoids from syn-copalyl diphosphate, click here
Other name(s): momilactone A synthase; OsMAS
Systematic name: 3β-hydroxy-9β-pimara-7,15-diene-19,6β-olide:NAD(P)+ oxidoreductase
Comments: The rice phytoalexin momilactone A is a diterpenoid secondary metabolite that is involved in the defense mechanism of the plant. Momilactone A is produced in response to attack by a pathogen through the perception of elicitor signal molecules such as chitin oligosaccharide, or after exposure to UV irradiation. The enzyme, which catalyses the last step in the biosynthesis of momilactone A, can use both NAD+ and NADP+ but activity is higher with NAD+ [1].
Links to other databases: BRENDA, EXPASY, IUBMB, KEGG
References:
1.  Atawong, A., Hasegawa, M. and Kodama, O. Biosynthesis of rice phytoalexin: enzymatic conversion of 3β-hydroxy-9β-pimara-7,15-dien-19,6β-olide to momilactone A. Biosci. Biotechnol. Biochem. 66 (2002) 566–570. [PMID: 12005050]
2.  Shimura, K., Okada, A., Okada, K., Jikumaru, Y., Ko, K.W., Toyomasu, T., Sassa, T., Hasegawa, M., Kodama, O., Shibuya, N., Koga, J., Nojiri, H. and Yamane, H. Identification of a biosynthetic gene cluster in rice for momilactones. J. Biol. Chem. 282 (2007) 34013–34018. [PMID: 17872948]
[EC 1.1.1.295 created 2008]
 
 
EC 1.3.7.6
Accepted name: phycoerythrobilin synthase
Reaction: (3Z)-phycoerythrobilin + 2 oxidized ferredoxin = biliverdin IXα + 2 reduced ferredoxin
Other name(s): PebS
Systematic name: (3Z)-phycoerythrobilin:ferredoxin oxidoreductase (from biliverdin IXα)
Comments: This enzyme, from a cyanophage infecting oceanic cyanobacteria of the Prochlorococcus genus, uses a four-electron reduction to carry out the reactions catalysed by EC 1.3.7.2 (15,16-dihydrobiliverdin:ferredoxin oxidoreductase) and EC 1.3.7.3 (phycoerythrobilin:ferredoxin oxidoreductase). 15,16-Dihydrobiliverdin is formed as a bound intermediate. Free 15,16-dihydrobiliverdin can also act as a substrate to form phycoerythrobilin.
Links to other databases: BRENDA, EXPASY, IUBMB, KEGG, PDB
References:
1.  Dammeyer, T., Bagby, S.C., Sullivan, M.B., Chisholm, S.W. and Frankenberg-Dinkel, N. Efficient phage-mediated pigment biosynthesis in oceanic cyanobacteria. Curr. Biol. 18 (2008) 442–448. [PMID: 18356052]
[EC 1.3.7.6 created 2008]
 
 
EC 1.3.99.24
Accepted name: 2-amino-4-deoxychorismate dehydrogenase
Reaction: (2S)-2-amino-4-deoxychorismate + FMN = 3-(1-carboxyvinyloxy)anthranilate + FMNH2
For diagram of enediyne antitumour antibiotic biosynthesis, click here
Glossary: (2S)-2-amino-4-deoxychorismate = (2S,3S)-3-(1-carboxyvinyloxy)-2,3-dihydroanthranilate
3-enolpyruvoylanthranilate = 3-(1-carboxyvinyloxy)anthranilate
Other name(s): ADIC dehydrogenase; 2-amino-2-deoxyisochorismate dehydrogenase; SgcG
Systematic name: (2S)-2-amino-4-deoxychorismate:FMN oxidoreductase
Comments: The sequential action of EC 2.6.1.86, 2-amino-4-deoxychorismate synthase and this enzyme leads to the formation of the benzoxazolinate moiety of the enediyne antitumour antibiotic C-1027 [1,2].
Links to other databases: BRENDA, EXPASY, IUBMB, KEGG
References:
1.  Van Lanen, S.G., Lin, S. and Shen, B. Biosynthesis of the enediyne antitumor antibiotic C-1027 involves a new branching point in chorismate metabolism. Proc. Natl. Acad. Sci. USA 105 (2008) 494–499. [PMID: 18182490]
2.  Yu, L., Mah, S., Otani, T. and Dedon, P. The benzoxazolinate of C-1027 confers intercalative DNA binding. J. Am. Chem. Soc. 117 (1995) 8877–8878.
[EC 1.3.99.24 created 2008]
 
 
EC 2.3.1.185
Accepted name: tropine acyltransferase
Reaction: an acyl-CoA + tropine = CoA + an O-acyltropine
For diagram of tropane alkaloid biosynthesis, click here
Glossary: tropine = tropan-3α-ol = 3α-hydroxytropane
Other name(s): tropine:acyl-CoA transferase; acetyl-CoA:tropan-3-ol acyltransferase; tropine acetyltransferase; tropine tigloyltransferase; TAT
Systematic name: acyl-CoA:tropine O-acyltransferase
Comments: This enzyme exhibits absolute specificity for the endo/3α configuration found in tropine as pseudotropine (tropan-3β-ol; see EC 2.3.1.186, pseudotropine acyltransferase) is not a substrate [3]. Acts on a wide range of aliphatic acyl-CoA derivatives, with tigloyl-CoA and acetyl-CoA being the best substrates. It is probably involved in the formation of the tropane alkaloid littorine, which is a precursor of hyoscyamine [4].
Links to other databases: BRENDA, EXPASY, IUBMB, KEGG, CAS registry number: 138440-79-6, 162535-29-7
References:
1.  Robins, R.J., Bachmann, P., Robinson, T., Rhodes, M.J. and Yamada, Y. The formation of 3α- and 3β-acetoxytropanes by Datura stramonium transformed root cultures involves two acetyl-CoA-dependent acyltransferases. FEBS Lett. 292 (1991) 293–297. [PMID: 1959620]
2.  Robins, R.J., Bachmann,P., Peerless, A.C.J. and Rabot, S. Esterification reactions in the biosynthesis of tropane alkaloids in transformed root cultures. Plant Cell, Tissue Organ Cult. 38 (1994) 241–247.
3.  Boswell, H.D., Dräger, B., McLauchlan, W.R., Portsteffen, A., Robins, D.J., Robins, R.J. and Walton, N.J. Specificities of the enzymes of N-alkyltropane biosynthesis in Brugmansia and Datura. Phytochemistry 52 (1999) 871–878. [PMID: 10626376]
4.  Li, R., Reed, D.W., Liu, E., Nowak, J., Pelcher, L.E., Page, J.E. and Covello, P.S. Functional genomic analysis of alkaloid biosynthesis in Hyoscyamus niger reveals a cytochrome P450 involved in littorine rearrangement. Chem. Biol. 13 (2006) 513–520. [PMID: 16720272]
[EC 2.3.1.185 created 2008]
 
 
EC 2.3.1.186
Accepted name: pseudotropine acyltransferase
Reaction: an acyl-CoA + pseudotropine = CoA + an O-acylpseudotropine
For diagram of tropane alkaloid biosynthesis, click here
Glossary: tropine = tropan-3β-ol = 3β-hydroxytropane
Other name(s): pseudotropine:acyl-CoA transferase; tigloyl-CoA:pseudotropine acyltransferase; acetyl-CoA:pseudotropine acyltransferase; pseudotropine acetyltransferase; pseudotropine tigloyltransferase; PAT
Systematic name: acyl-CoA:pseudotropine O-acyltransferase
Comments: This enzyme exhibits absolute specificity for the exo/3β configuration found in pseudotropine as tropine (tropan-3α-ol; see EC 2.3.1.185, tropine acyltransferase) and nortropine are not substrates [1]. Acts on a wide range of aliphatic acyl-CoA derivatives, including acetyl-CoA, β-methylcrotonyl-CoA and tigloyl-CoA [1].
Links to other databases: BRENDA, EXPASY, IUBMB, KEGG, CAS registry number: 138440-78-5, 162535-26-4
References:
1.  Rabot, S., Peerless, A.C.J. and Robins, R.J. Tigloyl-CoA:pseudotropine acyltransferase — an enzyme of tropane alkaloid biosynthesis. Phytochemistry 39 (1995) 315–322.
2.  Robins, R.J., Bachmann, P., Robinson, T., Rhodes, M.J. and Yamada, Y. The formation of 3α- and 3β-acetoxytropanes by Datura stramonium transformed root cultures involves two acetyl-CoA-dependent acyltransferases. FEBS Lett. 292 (1991) 293–297. [PMID: 1959620]
3.  Robins, R.J., Bachmann,P., Peerless, A.C.J. and Rabot, S. Esterification reactions in the biosynthesis of tropane alkaloids in transformed root cultures. Plant Cell, Tissue Organ Cult. 38 (1994) 241–247.
4.  Boswell, H.D., Dräger, B., McLauchlan, W.R., Portsteffen, A., Robins, D.J., Robins, R.J. and Walton, N.J. Specificities of the enzymes of N-alkyltropane biosynthesis in Brugmansia and Datura. Phytochemistry 52 (1999) 871–878. [PMID: 10626376]
[EC 2.3.1.186 created 2008]
 
 
EC 2.6.1.86
Accepted name: 2-amino-4-deoxychorismate synthase
Reaction: (2S)-2-amino-4-deoxychorismate + L-glutamate = chorismate + L-glutamine
For diagram of enediyne antitumour antibiotic biosynthesis, click here
Glossary: (2S)-2-amino-4-deoxychorismate = (2S,3S)-3-(1-carboxyvinyloxy)-2,3-dihydroanthranilate
Other name(s): ADIC synthase; 2-amino-2-deoxyisochorismate synthase; SgcD
Systematic name: (2S)-2-amino-4-deoxychorismate:2-oxoglutarate aminotransferase
Comments: Requires Mg2+. The reaction occurs in the reverse direction to that shown above. In contrast to most anthranilate-synthase I (ASI) homologues, this enzyme is not inhibited by tryptophan. In Streptomyces globisporus, the sequential action of this enzyme and EC 1.3.99.24, 2-amino-4-deoxychorismate dehydrogenase, leads to the formation of the benzoxazolinate moiety of the enediyne antitumour antibiotic C-1027 [1,2]. In certain Pseudomonads the enzyme participates in the biosynthesis of phenazine, a precursor for several compounds with antibiotic activity [3,4].
Links to other databases: BRENDA, EXPASY, IUBMB, KEGG
References:
1.  Van Lanen, S.G., Lin, S. and Shen, B. Biosynthesis of the enediyne antitumor antibiotic C-1027 involves a new branching point in chorismate metabolism. Proc. Natl. Acad. Sci. USA 105 (2008) 494–499. [PMID: 18182490]
2.  Yu, L., Mah, S., Otani, T. and Dedon, P. The benzoxazolinate of C-1027 confers intercalative DNA binding. J. Am. Chem. Soc. 117 (1995) 8877–8878.
3.  McDonald, M., Mavrodi, D.V., Thomashow, L.S. and Floss, H.G. Phenazine biosynthesis in Pseudomonas fluorescens: branchpoint from the primary shikimate biosynthetic pathway and role of phenazine-1,6-dicarboxylic acid. J. Am. Chem. Soc. 123 (2001) 9459–9460. [PMID: 11562236]
4.  Laursen, J.B. and Nielsen, J. Phenazine natural products: biosynthesis, synthetic analogues, and biological activity. Chem. Rev. 104 (2004) 1663–1686. [PMID: 15008629]
[EC 2.6.1.86 created 2008]
 
 
EC 2.7.1.161
Accepted name: CTP-dependent riboflavin kinase
Reaction: CTP + riboflavin = CDP + FMN
Other name(s): Methanocaldococcus jannaschii Mj0056; Mj0056
Systematic name: CTP:riboflavin 5′-phosphotransferase
Comments: This archaeal enzyme differs from EC 2.7.1.26, riboflavin kinase, in using CTP as the donor nucleotide. UTP, but not ATP or GTP, can also act as a phosphate donor but it is at least an order of magnitude less efficient than CTP.
Links to other databases: BRENDA, EXPASY, IUBMB, KEGG, PDB
References:
1.  Ammelburg, M., Hartmann, M.D., Djuranovic, S., Alva, V., Koretke, K.K., Martin, J., Sauer, G., Truffault, V., Zeth, K., Lupas, A.N. and Coles, M. A CTP-dependent archaeal riboflavin kinase forms a bridge in the evolution of cradle-loop barrels. Structure 15 (2007) 1577–1590. [PMID: 18073108]
[EC 2.7.1.161 created 2008]
 
 
EC 2.7.1.162
Accepted name: N-acetylhexosamine 1-kinase
Reaction: ATP + N-acetyl-D-hexosamine = ADP + N-acetyl-α-D-hexosamine 1-phosphate
Other name(s): NahK; LnpB; N-acetylgalactosamine/N-acetylglucosamine 1-kinase
Systematic name: ATP:N-acetyl-D-hexosamine 1-phosphotransferase
Comments: This enzyme is involved in the lacto-N-biose I/galacto-N-biose degradation pathway in the probiotic bacterium Bifidobacterium longum. Differs from EC 2.7.1.157, N-acetylgalactosamine kinase, as it can phosphorylate both N-acetylgalactosamine and N-acetylglucosamine at similar rates. Also has some activity with N-acetyl-D-mannosamine, D-talose and D-mannose as substrate. ATP can be replaced by GTP or ITP but with decreased enzyme activity. Requires a divalent cation, with Mg2+ resulting in by far the greatest stimulation of enzyme activity.
Links to other databases: BRENDA, EXPASY, IUBMB, KEGG
References:
1.  Nishimoto, M. and Kitaoka, M. Identification of N-acetylhexosamine 1-kinase in the complete lacto-N-biose I/galacto-N-biose metabolic pathway in Bifidobacterium longum. Appl. Environ. Microbiol. 73 (2007) 6444–6449. [PMID: 17720833]
[EC 2.7.1.162 created 2008]
 
 
EC 3.2.1.165
Accepted name: exo-1,4-β-D-glucosaminidase
Reaction: Hydrolysis of chitosan or chitosan oligosaccharides to remove successive D-glucosamine residues from the non-reducing termini
Glossary: GlcN = D-glucosamine = 2-amino-2-deoxy-D-glucopyranose
GlcNAc = N-acetyl-D-glucosamine
Other name(s): CsxA; GlcNase; exochitosanase; GlmA; exo-β-D-glucosaminidase; chitosan exo-1,4-β-D-glucosaminidase
Systematic name: chitosan exo-(1→4)-β-D-glucosaminidase
Comments: Chitosan is a partially or totally N-deacetylated chitin derivative that is found in the cell walls of some phytopathogenic fungi and comprises D-glucosamine residues with a variable content of GlcNAc residues [4]. Acts specifically on chitooligosaccharides and chitosan, having maximal activity on chitotetraose, chitopentaose and their corresponding alcohols [1]. The enzyme can degrade GlcN-GlcNAc but not GlcNAc-GlcNAc [3]. A member of the glycoside hydrolase family 2 (GH-2) [4].
Links to other databases: BRENDA, EXPASY, IUBMB, KEGG
References:
1.  Nanjo, F., Katsumi, R. and Sakai, K. Purification and characterization of an exo-β-D-glucosaminidase, a novel type of enzyme, from Nocardia orientalis. J. Biol. Chem. 265 (1990) 10088–10094. [PMID: 2351651]
2.  Nogawa, M., Takahashi, H., Kashiwagi, A., Ohshima, K., Okada, H. and Morikawa, Y. Purification and characterization of exo-β-D-glucosaminidase from a cellulolytic fungus, Trichoderma reesei PC-3-7. Appl. Environ. Microbiol. 64 (1998) 890–895. [PMID: 16349528]
3.  Fukamizo, T., Fleury, A., Côté, N., Mitsutomi, M. and Brzezinski, R. Exo-β-D-glucosaminidase from Amycolatopsis orientalis: catalytic residues, sugar recognition specificity, kinetics, and synergism. Glycobiology 16 (2006) 1064–1072. [PMID: 16877749]
4.  Côté, N., Fleury, A., Dumont-Blanchette, E., Fukamizo, T., Mitsutomi, M. and Brzezinski, R. Two exo-β-D-glucosaminidases/exochitosanases from actinomycetes define a new subfamily within family 2 of glycoside hydrolases. Biochem. J. 394 (2006) 675–686. [PMID: 16316314]
5.  Ike, M., Isami, K., Tanabe, Y., Nogawa, M., Ogasawara, W., Okada, H. and Morikawa, Y. Cloning and heterologous expression of the exo-β-D-glucosaminidase-encoding gene (gls93) from a filamentous fungus, Trichoderma reesei PC-3-7. Appl. Microbiol. Biotechnol. 72 (2006) 687–695. [PMID: 16636831]
[EC 3.2.1.165 created 2008]
 
 
EC 4.2.3.28
Accepted name: ent-cassa-12,15-diene synthase
Reaction: ent-copalyl diphosphate = ent-cassa-12,15-diene + diphosphate
For diagram of the biosynthesis of diterpenoids from ent-copalyl diphosphate, click here
Other name(s): OsDTC1; OsKS7
Systematic name: ent-copalyl-diphosphate diphosphate-lyase (ent-cassa-12,15-diene-forming)
Comments: This class I diterpene cyclase produces ent-cassa-12,15-diene, a precursor of the rice phytoalexins (-)-phytocassanes A-E. Phytoalexins are diterpenoid secondary metabolites that are involved in the defense mechanism of the plant, and are produced in response to pathogen attack through the perception of elicitor signal molecules such as chitin oligosaccharide, or after exposure to UV irradiation.
Links to other databases: BRENDA, EXPASY, IUBMB, KEGG
References:
1.  Cho, E.M., Okada, A., Kenmoku, H., Otomo, K., Toyomasu, T., Mitsuhashi, W., Sassa, T., Yajima, A., Yabuta, G., Mori, K., Oikawa, H., Toshima, H., Shibuya, N., Nojiri, H., Omori, T., Nishiyama, M. and Yamane, H. Molecular cloning and characterization of a cDNA encoding ent-cassa-12,15-diene synthase, a putative diterpenoid phytoalexin biosynthetic enzyme, from suspension-cultured rice cells treated with a chitin elicitor. Plant J. 37 (2004) 1–8. [PMID: 14675427]
[EC 4.2.3.28 created 2008]
 
 
EC 4.2.3.29
Accepted name: ent-sandaracopimaradiene synthase
Reaction: ent-copalyl diphosphate = ent-sandaracopimara-8(14),15-diene + diphosphate
For diagram of the biosynthesis of diterpenoids from ent-copalyl diphosphate, click here
Other name(s): OsKS10; ent-sandaracopimara-8(14),15-diene synthase
Systematic name: ent-copalyl-diphosphate diphosphate-lyase [ent-sandaracopimara-8(14),15-diene-forming]
Comments: ent-Sandaracopimaradiene is a precursor of the rice oryzalexins A-F. Phytoalexins are diterpenoid secondary metabolites that are involved in the defense mechanism of the plant, and are produced in response to pathogen attack through the perception of elicitor signal molecules such as chitin oligosaccharide, or after exposure to UV irradiation. As a minor product, this enzyme also forms ent-pimara-8(14),15-diene, which is the sole product of EC 4.2.3.30, ent-pimara-8(14),15-diene synthase. ent-Pimara-8(14),15-diene is not a precursor in the biosynthesis of either gibberellins or phytoalexins [2].
Links to other databases: BRENDA, EXPASY, IUBMB, KEGG
References:
1.  Otomo, K., Kanno, Y., Motegi, A., Kenmoku, H., Yamane, H., Mitsuhashi, W., Oikawa, H., Toshima, H., Itoh, H., Matsuoka, M., Sassa, T. and Toyomasu, T. Diterpene cyclases responsible for the biosynthesis of phytoalexins, momilactones A, B, and oryzalexins A-F in rice. Biosci. Biotechnol. Biochem. 68 (2004) 2001–2006. [PMID: 15388982]
2.  Kanno, Y., Otomo, K., Kenmoku, H., Mitsuhashi, W., Yamane, H., Oikawa, H., Toshima, H., Matsuoka, M., Sassa, T. and Toyomasu, T. Characterization of a rice gene family encoding type-A diterpene cyclases. Biosci. Biotechnol. Biochem. 70 (2006) 1702–1710. [PMID: 16861806]
[EC 4.2.3.29 created 2008]
 
 
EC 4.2.3.30
Accepted name: ent-pimara-8(14),15-diene synthase
Reaction: ent-copalyl diphosphate = ent-pimara-8(14),15-diene + diphosphate
For diagram of the biosynthesis of diterpenoids from ent-copalyl diphosphate, click here
Other name(s): OsKS5
Systematic name: ent-copalyl-diphosphate diphosphate-lyase [ent-pimara-8(14),15-diene-forming]
Comments: Unlike EC 4.2.3.29, ent-sandaracopimaradiene synthase, which can produce both ent-sandaracopimaradiene and ent-pimara-8(14),15-diene, this diterpene cyclase produces only ent-pimara-8(14),15-diene. ent-Pimara-8(14),15-diene is not a precursor in the biosynthesis of either gibberellins or phytoalexins.
Links to other databases: BRENDA, EXPASY, IUBMB, KEGG
References:
1.  Kanno, Y., Otomo, K., Kenmoku, H., Mitsuhashi, W., Yamane, H., Oikawa, H., Toshima, H., Matsuoka, M., Sassa, T. and Toyomasu, T. Characterization of a rice gene family encoding type-A diterpene cyclases. Biosci. Biotechnol. Biochem. 70 (2006) 1702–1710. [PMID: 16861806]
[EC 4.2.3.30 created 2008]
 
 
EC 4.2.3.31
Accepted name: ent-pimara-9(11),15-diene synthase
Reaction: ent-copalyl diphosphate = ent-pimara-9(11),15-diene + diphosphate
For diagram of the biosynthesis of diterpenoids from ent-copalyl diphosphate, click here
Other name(s): PMD synthase
Systematic name: ent-copalyl-diphosphate diphosphate-lyase [ent-pimara-9(11),15-diene-forming]
Comments: This enzyme is involved in the biosynthesis of the diterpenoid viguiepinol and requires Mg2+, Co2+, Zn2+ or Ni2+ for activity.
Links to other databases: BRENDA, EXPASY, IUBMB, KEGG
References:
1.  Ikeda, C., Hayashi, Y., Itoh, N., Seto, H. and Dairi, T. Functional analysis of eubacterial ent-copalyl diphosphate synthase and pimara-9(11),15-diene synthase with unique primary sequences. J. Biochem. 141 (2007) 37–45. [PMID: 17148547]
[EC 4.2.3.31 created 2008]
 
 
EC 4.2.3.32
Accepted name: levopimaradiene synthase
Reaction: (+)-copalyl diphosphate = abieta-8(14),12-diene + diphosphate
For diagram of abietadiene, abietate, isopimaradiene, labdadienol and sclareol biosynthesis, click here and for diagram of abietadiene, levopimaradiene and isopimara-7,15-diene biosynthesis, click here
Glossary: levopimaradiene = abieta-8(14),12-diene
Other name(s): PtTPS-LAS; LPS; copalyl-diphosphate diphosphate-lyase [abieta-8(14),12-diene-forming]
Systematic name: (+)-copalyl-diphosphate diphosphate-lyase [abieta-8(14),12-diene-forming]
Comments: In Ginkgo, the enzyme catalyses the initial cyclization step in the biosynthesis of ginkgolides, a structurally unique family of diterpenoids that are highly specific platelet-activating-factor receptor antagonists [1]. Levopimaradiene is widely distributed in higher plants. In some species the enzyme also forms abietadiene, palustradiene, and neoabietadiene [2].
Links to other databases: BRENDA, EXPASY, IUBMB, KEGG
References:
1.  Schepmann, H.G., Pang, J. and Matsuda, S.P. Cloning and characterization of Ginkgo biloba levopimaradiene synthase which catalyzes the first committed step in ginkgolide biosynthesis. Arch. Biochem. Biophys. 392 (2001) 263–269. [PMID: 11488601]
2.  Ro, D.K. and Bohlmann, J. Diterpene resin acid biosynthesis in loblolly pine (Pinus taeda): functional characterization of abietadiene/levopimaradiene synthase (PtTPS-LAS) cDNA and subcellular targeting of PtTPS-LAS and abietadienol/abietadienal oxidase (PtAO, CYP720B1). Phytochemistry 67 (2006) 1572–1578. [PMID: 16497345]
[EC 4.2.3.32 created 2008, modified 2012]
 
 
EC 4.2.3.33
Accepted name: stemar-13-ene synthase
Reaction: 9α-copalyl diphosphate = stemar-13-ene + diphosphate
For diagram of the biosynthesis of diterpenoids from 9alpha-copalyl diphosphate, click here
Glossary: syn-copalyl diphosphate = 9α-copalyl diphosphate
Other name(s): OsDTC2; OsK8; OsKL8; OsKS8; stemarene synthase; syn-stemar-13-ene synthase
Systematic name: 9α-copalyl-diphosphate diphosphate-lyase (stemar-13-ene-forming)
Comments: This diterpene cyclase produces stemar-13-ene, a putative precursor of the rice phytoalexin oryzalexin S. Phytoalexins are diterpenoid secondary metabolites that are involved in the defense mechanism of the plant, and are produced in response to pathogen attack through the perception of elicitor signal molecules such as chitin oligosaccharide, or after exposure to UV irradiation.
Links to other databases: BRENDA, EXPASY, IUBMB, KEGG
References:
1.  Mohan, R.S., Yee, N.K., Coates, R.M., Ren, Y.Y., Stamenkovic, P., Mendez, I. and West, C.A. Biosynthesis of cyclic diterpene hydrocarbons in rice cell suspensions: conversion of 9,10-syn-labda-8(17),13-dienyl diphosphate to 9β-pimara-7,15-diene and stemar-13-ene. Arch. Biochem. Biophys. 330 (1996) 33–47. [PMID: 8651702]
2.  Nemoto, T., Cho, E.M., Okada, A., Okada, K., Otomo, K., Kanno, Y., Toyomasu, T., Mitsuhashi, W., Sassa, T., Minami, E., Shibuya, N., Nishiyama, M., Nojiri, H. and Yamane, H. Stemar-13-ene synthase, a diterpene cyclase involved in the biosynthesis of the phytoalexin oryzalexin S in rice. FEBS Lett. 571 (2004) 182–186. [PMID: 15280039]
[EC 4.2.3.33 created 2008]
 
 
EC 4.2.3.34
Accepted name: stemod-13(17)-ene synthase
Reaction: 9α-copalyl diphosphate = stemod-13(17)-ene + diphosphate
For diagram of the biosynthesis of diterpenoids from 9alpha-copalyl diphosphate, click here
Glossary: syn-copalyl diphosphate = 9α-copalyl diphosphate
exo-stemodene = stemod-13(17)-ene
Other name(s): OsKSL11; stemodene synthase
Systematic name: 9α-copalyl-diphosphate diphosphate-lyase [stemod-13(17)-ene-forming]
Comments: This enzyme catalyses the committed step in the biosynthesis of the stemodane family of diterpenoid secondary metabolites, some of which possess mild antiviral activity. The enzyme also produces stemod-12-ene and stemar-13-ene as minor products.
Links to other databases: BRENDA, EXPASY, IUBMB, KEGG
References:
1.  Morrone, D., Jin, Y., Xu, M., Choi, S.Y., Coates, R.M. and Peters, R.J. An unexpected diterpene cyclase from rice: functional identification of a stemodene synthase. Arch. Biochem. Biophys. 448 (2006) 133–140. [PMID: 16256063]
[EC 4.2.3.34 created 2008]
 
 
EC 4.2.3.35
Accepted name: syn-pimara-7,15-diene synthase
Reaction: 9α-copalyl diphosphate = 9β-pimara-7,15-diene + diphosphate
For diagram of the biosynthesis of diterpenoids from 9alpha-copalyl diphosphate, click here
Glossary: syn-copalyl diphosphate = 9α-copalyl diphosphate
syn-pimara-7,15-diene = 9β-pimara-7,15-diene
Other name(s): 9β-pimara-7,15-diene synthase; OsDTS2; OsKS4
Systematic name: 9α-copalyl-diphosphate diphosphate-lyase (9β-pimara-7,15-diene-forming)
Comments: This enzyme is a class I terpene synthase [1]. 9β-Pimara-7,15-diene is a precursor of momilactones A and B, rice diterpenoid phytoalexins that are produced in response to attack (by a pathogen, elicitor or UV irradiation) and are involved in the defense mechanism of the plant. Momilactone B can also act as an allochemical, being constitutively produced in the root of the plant and secreted to the rhizosphere where it suppresses the growth of neighbouring plants and soil microorganisms [1].
Links to other databases: BRENDA, EXPASY, IUBMB, KEGG
References:
1.  Wilderman, P.R., Xu, M., Jin, Y., Coates, R.M. and Peters, R.J. Identification of syn-pimara-7,15-diene synthase reveals functional clustering of terpene synthases involved in rice phytoalexin/allelochemical biosynthesis. Plant Physiol. 135 (2004) 2098–2105. [PMID: 15299118]
2.  Otomo, K., Kanno, Y., Motegi, A., Kenmoku, H., Yamane, H., Mitsuhashi, W., Oikawa, H., Toshima, H., Itoh, H., Matsuoka, M., Sassa, T. and Toyomasu, T. Diterpene cyclases responsible for the biosynthesis of phytoalexins, momilactones A, B, and oryzalexins A-F in rice. Biosci. Biotechnol. Biochem. 68 (2004) 2001–2006. [PMID: 15388982]
[EC 4.2.3.35 created 2008]
 
 
EC 5.5.1.14
Accepted name: syn-copalyl-diphosphate synthase
Reaction: geranylgeranyl diphosphate = 9α-copalyl diphosphate
For diagram of diterpenoids from 9α-copalyl diphosphate, click here
Glossary: syn-copalyl diphosphate = 9α-copalyl diphosphate
Other name(s): OsCyc1; OsCPSsyn; syn-CPP synthase; syn-copalyl diphosphate synthase; 9α-copalyl-diphosphate lyase (decyclizing)
Systematic name: 9α-copalyl-diphosphate lyase (ring-opening)
Comments: Requires a divalent metal ion, preferably Mg2+, for activity. This class II terpene synthase produces syn-copalyl diphosphate, a precursor of several rice phytoalexins, including oryzalexin S and momilactones A and B. Phytoalexins are diterpenoid secondary metabolites that are involved in the defense mechanism of the plant, and are produced in response to pathogen attack through the perception of elicitor signal molecules such as chitin oligosaccharide, or after exposure to UV irradiation. The enzyme is constitutively expressed in the roots of plants where one of its products, momilactone B, acts as an allelochemical (a molecule released into the environment to suppress the growth of neighbouring plants). In other tissues the enzyme is upregulated by conditions that stimulate the biosynthesis of phytoalexins.
Links to other databases: BRENDA, EXPASY, IUBMB, KEGG
References:
1.  Otomo, K., Kenmoku, H., Oikawa, H., Konig, W.A., Toshima, H., Mitsuhashi, W., Yamane, H., Sassa, T. and Toyomasu, T. Biological functions of ent- and syn-copalyl diphosphate synthases in rice: key enzymes for the branch point of gibberellin and phytoalexin biosynthesis. Plant J. 39 (2004) 886–893. [PMID: 15341631]
2.  Xu, M., Hillwig, M.L., Prisic, S., Coates, R.M. and Peters, R.J. Functional identification of rice syn-copalyl diphosphate synthase and its role in initiating biosynthesis of diterpenoid phytoalexin/allelopathic natural products. Plant J. 39 (2004) 309–318. [PMID: 15255861]
[EC 5.5.1.14 created 2008]
 
 


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