| EC |
2.1.1.115 |
| Accepted name: |
(RS)-1-benzyl-1,2,3,4-tetrahydroisoquinoline N-methyltransferase |
| Reaction: |
S-adenosyl-L-methionine + (RS)-1-benzyl-1,2,3,4-tetrahydroisoquinoline = S-adenosyl-L-homocysteine + N-methyl-(RS)-1-benzyl-1,2,3,4-tetrahydroisoquinoline |
| Other name(s): |
norreticuline N-methyltransferase |
| Systematic name: |
S-adenosyl-L-methionine:(RS)-1-benzyl-1,2,3,4-tetrahydroisoquinoline N-methyltransferase |
| Comments: |
Broad substrate specificity for (RS)-1-benzyl-1,2,3,4-tetrahydroisoquinolines; including coclaurine, norcoclaurine, isococlaurine, norarmepavine, norreticuline and tetrahydropapaverine. Both R- and S-enantiomers are methylated. The enzyme participates in the pathway leading to benzylisoquinoline alkaloid synthesis in plants. The physiological substrate is likely to be coclaurine. The enzyme was earlier termed norreticuline N-methyltransferase. However, norreticuline has not been found to occur in nature and that name does not reflect the broad specificity of the enzyme for (RS)-1-benzyl-1,2,3,4-tetrahydroisoquinolines. |
| Links to other databases: |
BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 132084-82-3 |
| References: |
| 1. |
Frenzel, T., Zenk, M.H. Purification and characterization of three isoforms of S-adenosyl-L-methionine: (R,S)-tetrahydrobenzyl-isoquinoline N-methyltransferase from Berberis koetineana cell cultures. Phytochemistry 29 (1990) 3491–3497. |
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| [EC 2.1.1.115 created 1999] |
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| EC |
2.1.1.128 |
| Accepted name: |
(RS)-norcoclaurine 6-O-methyltransferase |
| Reaction: |
S-adenosyl-L-methionine + (RS)-norcoclaurine = S-adenosyl-L-homocysteine + (RS)-coclaurine |
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For diagram of reticuline biosynthesis, click here |
| Glossary: |
norcoclaurine = 6,7-dihydroxy-1-[(4-hydroxyphenyl)methyl]-1,2,3,4-tetrahydroisoquinoline |
| Systematic name: |
S-adenosyl-L-methionine:(RS)-norcoclaurine 6-O-methyltransferase |
| Comments: |
The enzyme will also catalyse the 6-O-methylation of (RS)-norlaudanosoline to form 6-O-methyl-norlaudanosoline, but this alkaloid has not been found to occur in plants. |
| Links to other databases: |
BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 89700-33-4 |
| References: |
| 1. |
Rueffer, M., Nagakura, N., Zenk, M.H. Partial purification and properties of S-adenosyl-L-methionine:(R),(S)-norlaudanosoline-6-O-methyltransferase from Argemone platyceras cell cultures. Planta Med. 49 (1983) 131–137. [PMID: 17405035] |
| 2. |
Sato, F., Tsujita, T., Katagiri, Y., Yoshida, S. and Yamada, Y. Purification and characterization of S-adenosyl-L-methionine:norcoclaurine 6-O-methyltransferase from cultured Coptis japonica cells. Eur. J. Biochem. 225 (1994) 125–131. [DOI] [PMID: 7925429] |
| 3. |
Stadler, R., Zenk, M.H. A revision of the generally accepted pathway for the biosynthesis of the benzyltetrahydroisoquinoline reticuline. Liebigs Ann. Chem. (1990) 555–562. [DOI] |
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| [EC 2.1.1.128 created 1999] |
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| EC |
2.1.1.140 |
| Accepted name: |
(S)-coclaurine-N-methyltransferase |
| Reaction: |
S-adenosyl-L-methionine + (S)-coclaurine = S-adenosyl-L-homocysteine + (S)-N-methylcoclaurine |
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For diagram of reticuline-biosynthesis pathway, click here |
| Systematic name: |
S-adenosyl-L-methionine:(S)-coclaurine-N-methyltransferase |
| Comments: |
The enzyme is specific for the (S)-isomer of coclaurine. Norcoclaurine can also act as an acceptor. |
| Links to other databases: |
BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 167398-06-3 |
| References: |
| 1. |
Loeffler, S., Deus-Neumann, B. and Zenk, M.H. S-Adenosyl-L-methionine: (S)-coclaurine-N-methyltransferase from Tinospora cordifolia. Phytochemistry 38 (1995) 1387–1395. [DOI] |
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| [EC 2.1.1.140 created 2001] |
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| EC |
2.1.1.291 |
| Accepted name: |
(R,S)-reticuline 7-O-methyltransferase |
| Reaction: |
(1) S-adenosyl-L-methionine + (S)-reticuline = S-adenosyl-L-homocysteine + (S)-laudanine
(2) S-adenosyl-L-methionine + (R)-reticuline = S-adenosyl-L-homocysteine + (R)-laudanine |
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For diagram of laudanine biosynthesis, click here |
| Glossary: |
(S)-reticuline = (1S)-1-[(3-hydroxy-4-methoxyphenyl)methyl]-6-methoxy-2-methyl-1,2,3,4-tetrahydroisoquinolin-7-ol
(R)-reticuline = (1R)-1-[(3-hydroxy-4-methoxyphenyl)methyl]-6-methoxy-2-methyl-1,2,3,4-tetrahydroisoquinolin-7-ol
(S)-laudanine = 5-[((1S)-6,7-dimethoxy-2-methyl-1,2,3,4-tetrahydroisoquinolin-1-yl)methyl]-2-methoxyphenol
(R)-laudanine = 5-[((1R)-6,7-dimethoxy-2-methyl-1,2,3,4-tetrahydroisoquinolin-1-yl)methyl]-2-methoxyphenol
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| Systematic name: |
S-adenosyl-L-methionine:(R,S)-reticuline 7-O-methyltransferase |
| Comments: |
The enzyme from the plant Papaver somniferum (opium poppy) methylates (S)- and (R)-reticuline with equal efficiency and is involved in the biosynthesis of tetrahydrobenzylisoquinoline alkaloids. |
| Links to other databases: |
BRENDA, EXPASY, KEGG, MetaCyc |
| References: |
| 1. |
Ounaroon, A., Decker, G., Schmidt, J., Lottspeich, F. and Kutchan, T.M. (R,S)-Reticuline 7-O-methyltransferase and (R,S)-norcoclaurine 6-O-methyltransferase of Papaver somniferum - cDNA cloning and characterization of methyl transfer enzymes of alkaloid biosynthesis in opium poppy. Plant J. 36 (2003) 808–819. [DOI] [PMID: 14675446] |
| 2. |
Weid, M., Ziegler, J. and Kutchan, T.M. The roles of latex and the vascular bundle in morphine biosynthesis in the opium poppy, Papaver somniferum. Proc. Natl. Acad. Sci. USA 101 (2004) 13957–13962. [DOI] [PMID: 15353584] |
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| [EC 2.1.1.291 created 2013] |
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| EC |
3.5.99.14 |
| Accepted name: |
(S)-norcoclaurine synthase |
| Reaction: |
(S)-norcoclaurine + H2O = dopamine + 4-hydroxyphenylacetaldehyde |
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For diagram of reaction, click here |
| Glossary: |
dopamine = 4-(2-aminoethyl)benzene-1,2-diol |
| Other name(s): |
(S)-norlaudanosoline synthase; 4-hydroxyphenylacetaldehyde hydro-lyase (adding dopamine); 4-hydroxyphenylacetaldehyde hydro-lyase [adding dopamine, (S)-norcoclaurine-forming] |
| Systematic name: |
(S)-norcoclaurine dopamine hydrolase (4-hydroxyphenylacetaldehyde-forming) |
| Comments: |
The reaction makes a six-membered ring by forming a bond between C-6 of the 3,4-dihydroxyphenyl group of the dopamine and C-1 of the aldehyde in the imine formed between the substrates. The product is the precursor of the benzylisoquinoline alkaloids in plants. The enzyme, formerly known as (S)-norlaudanosoline synthase, will also catalyse the reaction of 4-(2-aminoethyl)benzene-1,2-diol + (3,4-dihydroxyphenyl)acetaldehyde to form (S)-norlaudanosoline, but this alkaloid has not been found to occur in plants. |
| Links to other databases: |
BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 79122-01-3 |
| References: |
| 1. |
Stadler, R., Zenk, M.H. A revision of the generally accepted pathway for the biosynthesis of the benzyltetrahydroisoquinoline reticuline. Liebigs Ann. Chem. (1990) 555–562. [DOI] |
| 2. |
Stadler, R., Kutchan, T.M., Zenk, M.H. (S)-Norcoclaurine is the central intermediate in benzylisoquinoline alkaloid biosynthesis. Phytochemistry 28 (1989) 1083–1086. [DOI] |
| 3. |
Samanani, N. and Facchini, P.J. Purification and characterization of norcoclaurine synthase. The first committed enzyme in benzylisoquinoline alkaloid biosynthesis in plants. J. Biol. Chem. 277 (2002) 33878–33883. [DOI] [PMID: 12107162] |
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| [EC 3.5.99.14 created 1984 as EC 4.2.1.78, modified 1999, transferred 2024 to EC 3.5.99.14] |
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EC
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4.2.1.78
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| Transferred entry: | (S)-norcoclaurine synthase. Now 3.5.99.14, (S)-norcoclaurine synthase
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| [EC 4.2.1.78 created 1984, modified 1999, deleted 2024] |
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