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MetaCyc Compound Class: a methylated methyl donor

Synonyms: a methylated methyl acceptor

Superclasses: an acceptor a methyl group donor

A methyl group donor is a compound that can donate a methyl group to another compound in a reaction catalyzed by enzymes that belong to the methyltransferase group. Prior to donating the methyl group the compound is a methylated methyl donor and after donating it the compound is a demethylated methyl donor.

Since methylation reactions are sometimes reversible, the distinction between a methyl group donor and a methyl group acceptor is not always determined by the actual chemical entity, but by the role it plays in a particular reaction. However, some compounds are often used as methyl group donors by the methyltransferases in reactions that are physiologically unidirectional.

By far, the most common methyl group donor in biology is S-adenosyl-L-methionine. However, other methyl donors exist, including methanol, N5-methyl tetrahydrofolate, N5-methyltetrahydromethanopterin, methylamine, dimethylamine, trimethylamine, and methanethiol.

This particular entry is used when the identity of the methyl group donor (or acceptor) is not known or cannot be defined.

a methylated methyl donor compound structure

glycine betaine


Reactions known to consume the compound:

beta-carboline biosynthesis :
harmol + a methylated methyl donor → harmine + a demethylated methyl donor
harmalol + a methylated methyl donor → harmaline + a demethylated methyl donor

caffeine degradation II :
1,3,7-trimethylurate + a methylated methyl donor → 1,3,7,9-tetramethylurate + a demethylated methyl donor

cocaine biosynthesis :
4-(1-methyl-2-pyrrolidinyl)-3-oxobutanoate + a methylated methyl donor + H+ → 4-(1-methyl-2-pyrrolidinyl)-3-oxobutanoate methyl ester + a demethylated methyl donor

dimethylsulfoniopropanoate biosynthesis III (algae) :
2-hydroxy-4-methylthiobutanoate + a methylated methyl donor + H+ → dimethylsulfonio-2-hydroxybutanoate + a demethylated methyl donor

K-252 biosynthesis :
K252b + a methylated methyl donor → K252a + a demethylated methyl donor

methiin metabolism :
glutathione + a methylated methyl donorS-methylglutathione + a demethylated methyl donor

sorgoleone biosynthesis :
dihydrosorgoleone + a methylated methyl donor → methoxydihydrosorgoleone + a demethylated methyl donor

Reactions known to produce the compound:

autoinducer AI-2 biosynthesis I , autoinducer AI-2 biosynthesis II (Vibrio) , L-methionine degradation I (to L-homocysteine) , S-adenosyl-L-methionine cycle I , S-adenosyl-L-methionine cycle II :
S-adenosyl-L-methionine + a demethylated methyl donor → S-adenosyl-L-homocysteine + a methylated methyl donor + H+

caffeine degradation I (main, plants) :
3-methylxanthine + a demethylated methyl donor → xanthine + a methylated methyl donor
theophylline + a demethylated methyl donor → 3-methylxanthine + a methylated methyl donor
caffeine + a demethylated methyl donor → theophylline + a methylated methyl donor

caffeine degradation II :
O(2),1,7,9-tetramethylurate + a demethylated methyl donor → O(2),1,9-trimethylurate + a methylated methyl donor

In Reactions of unknown directionality:

Not in pathways:
cycloartenol + a demethylated methyl donor = 4α,14α-dimethyl-9β,19-cyclo-5α-cholest-24-en-3β-ol + a methylated methyl donor
4α-methyl-5α-cholesta-7,24-dien-3β-ol + a demethylated methyl donor = 5α-cholesta-7,24-dien-3β-ol + a methylated methyl donor
24-methylenecycloartanol + a demethylated methyl donor = cycloeucalenol + a methylated methyl donor
24-methylenelophenol + a demethylated methyl donor = episterol + a methylated methyl donor
24-ethylidenelophenol + a demethylated methyl donor = avenasterol + a methylated methyl donor

Report Errors or Provide Feedback
Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
Page generated by SRI International Pathway Tools version 19.0 on Wed Sep 2, 2015, biocyc14.