EC 2.1.1.352     
Accepted name: 3-O-acetyl-4′-O-demethylpapaveroxine 4′-O-methyltransferase
Reaction: S-adenosyl-L-methionine + 3-O-acetyl-4′-O-demethylpapaveroxine = S-adenosyl-L-homocysteine + 3-O-acetylpapaveroxine
Glossary: 3-O-acetyl-4′-O-demethylpapaveroxine = 6-{(S)-acetoxy[(5R)-4-hydroxy-6-methyl-5,6,7,8-tetrahydro[1,3]dioxolo[4,5-g]isoquinolin-5-yl]methyl}-2,3-dimethoxybenzaldehyde
3-O-acetylpapaveroxine = 6-{(S)-acetoxy[(5R)-4-methoxy-6-methyl-5,6,7,8-tetrahydro[1,3]dioxolo[4,5-g]isoquinolin-5-yl]methyl}-2,3-dimethoxybenzaldehyde
Systematic name: S-adenosyl-L-methionine:3-O-acetyl-4′-O-demethylpapaveroxine 4′-O-methyltransferase
Comments: This activity is part of the noscapine biosynthesis pathway, as characterized in the plant Papaver somniferum (opium poppy). It is catalysed by heterodimeric complexes of the OMT2 gene product and the product of either OMT3 or 6OMT. OMT2 is the catalytic subunit in both complexes.
References:
1.  Li, Y. and Smolke, C.D. Engineering biosynthesis of the anticancer alkaloid noscapine in yeast. Nat. Commun. 7:12137 (2016). [PMID: 27378283]
2.  Park, M.R., Chen, X., Lang, D.E., Ng, K.KS. and Facchini, P.J. Heterodimeric O-methyltransferases involved in the biosynthesis of noscapine in opium poppy. Plant J. 95 (2018) 252–267. [PMID: 29723437]
[EC 2.1.1.352 created 2018]
 
 
EC 3.1.1.105     
Accepted name: 3-O-acetylpapaveroxine carboxylesterase
Reaction: 3-O-acetylpapaveroxine + H2O = narcotine hemiacetal + acetate
Glossary: 3-O-acetylpapaveroxine = 6-{(S)-acetoxy[(5R)-4-methoxy-6-methyl-5,6,7,8-tetrahydro[1,3]dioxolo[4,5-g]isoquinolin-5-yl]methyl}-2,3-dimethoxybenzaldehyde
narcotine hemiacetal = (3S)-6,7-dimethoxy-3-[(5R)-4-methoxy-6-methyl-5,6,7,8-tetrahydro[1,3]dioxolo[4,5-g]isoquinolin-5-yl]-1,3-dihydroisobenzofuran-1-ol
Other name(s): CXE1 (gene name)
Systematic name: 3-O-acetylpapaveroxine acetatehydrolase
Comments: The enzyme, characterized from the plant Papaver somniferum (opium poppy), participates in the biosynthesis of the isoquinoline alkaloid noscapine.
References:
1.  Dang, T.T., Chen, X. and Facchini, P.J. Acetylation serves as a protective group in noscapine biosynthesis in opium poppy. Nat. Chem. Biol. 11 (2015) 104–106. [PMID: 25485687]
2.  Park, M.R., Chen, X., Lang, D.E., Ng, K.KS. and Facchini, P.J. Heterodimeric O-methyltransferases involved in the biosynthesis of noscapine in opium poppy. Plant J. 95 (2018) 252–267. [PMID: 29723437]
[EC 3.1.1.105 created 2019]