EC 2.1.1.69     
Accepted name: 5-hydroxyfuranocoumarin 5-O-methyltransferase
Reaction: (1) S-adenosyl-L-methionine + a 5-hydroxyfurocoumarin = S-adenosyl-L-homocysteine + a 5-methoxyfurocoumarin (general reaction)
(2) S-adenosyl-L-methionine + bergaptol = S-adenosyl-L-homocysteine + bergapten
Glossary: bergaptol = 5-hydroxypsoralen
O-methylbergaptol = bergapten = 5-methoxypsoralen
Other name(s): furanocoumarin 5-methyltransferase; furanocoumarin 5-O-methyltransferase; bergaptol 5-O-methyltransferase; bergaptol O-methyltransferase; bergaptol methyltransferase; S-adenosyl-L-methionine:bergaptol O-methyltransferase; BMT; S-adenosyl-L-methionine:5-hydroxyfuranocoumarin 5-O-methyltransferase
Systematic name: S-adenosyl-L-methionine:5-hydroxyfurocoumarin 5-O-methyltransferase
Comments: Converts bergaptol into bergapten, which has therapeutic potential in the treatment of psoriasis as it has photosensitizing and antiproliferative activities [4]. The enzyme methylates the 5-hydroxy group of some hydroxy- and methylcoumarins, such as 5-hydroxyxanthotoxin [3], but has little activity on non-coumarin phenols [1]. Caffeate, 5-hydroxyferulate and daphnetin are not substrates [4]. Cu2+, Zn2+ and Co2+ cause enzyme inhibition [4]. (see also EC 2.1.1.70, 8-hydroxyfuranocoumarin 8-O-methyltransferase)
References:
1.  Thompson, H.J., Sharma, S.K. and Brown, S.A. O-Methyltransferases of furanocoumarin biosynthesis. Arch. Biochem. Biophys. 188 (1978) 272–281. [PMID: 28084]
2.  Sharma, S.K., Garrett, J.M. and Brown, S.A. Separation of the S-adenosylmethionine: 5- and 8-hydroxyfuranocoumarin O-methyltransferases of Ruta graveolens L. by general ligand affinity chromatography. Z. Naturforsch. [C] 34C (1979) 387–391. [PMID: 156999]
3.  Hauffe, K.D., Hahlbrock, K. and Scheel, D. Elicitor-stimulated furanocoumarin biosynthesis in cultured parsley cells - S-adenosyl-L-methionine-bergaptol and S-adenosyl-L-methionine-xanthotoxol O-methyltransferases. Z. Naturforsch. C: Biosci. 41 (1986) 228–239.
4.  Hehmann, M., Lukačin, R., Ekiert, H. and Matern, U. Furanocoumarin biosynthesis in Ammi majus L. Cloning of bergaptol O-methyltransferase. Eur. J. Biochem. 271 (2004) 932–940. [PMID: 15009205]
[EC 2.1.1.69 created 1984 (EC 2.1.1.92 created 1989, incorporated 2006), modified 2006]
 
 
EC 2.1.1.92      
Deleted entry: bergaptol O-methyltransferase. Now included with EC 2.1.1.69, 5-hydroxyfuranocoumarin 5-O-methyltransferase. The reaction with bergaptol is a specific example of the general reaction associated with EC 2.1.1.69
[EC 2.1.1.92 created 1989, deleted 2006]