transmethylation


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transmethylation

[¦tranz‚meth·ə′lā·shən]
(biochemistry)
A metabolic reaction in which a methyl group is transferred from one compound to another; methionine and choline are important donors of methyl groups.
References in periodicals archive ?
Cystathionine was generated by transmethylation in the process of Met metabolism [23], and then cystathionine transsulfuration produced cysteine [24], and cysteine finally transformed into taurine [25], which plays important roles in antioxidant [24].
After transmethylation reactions, SAM is converted into S-adenosylhomocysteine (SAH) and then hydrolyzed to adenosine and Hcy.
A metabolic disorder of vitamin B12 dependent transmethylation pathway induced by HIV or cytokine activation is considered the possible cause of vacuolar myelopathy associated with AIDS.
The authors would like to thank Funcap, CNPq and Capes for their financial support and scholarships; to the Chemistry Laboratory of Natural Products and Biotechnology of the Federal University of Ceara, for GC/MS of esters obtained by transmethylation of fish fatty acids, were analyzed.
The fatty acid composition of the frying oils was determined by gas chromatography (GC) of fatty acid methyl esters (FAME) prepared by transmethylation with BF3/methanol at 100[degrees]C for 45 min [12].
Methyl esters were prepared by transmethylation, using KOH 2 mol/L in methanol and n-heptane, according to method 5509 of the ISO (1978).
In Parkinson's disease (PD) patients undergoing levodopa (LD) therapy, plasma homocysteine (Hcy) levels are elevated as a result of the transmethylation of LD via catechol O-methyl transferase (COMT) [4, 5].
SAM2 encodes an enzyme that catalyzes the formation of S-adenosylmethionine, an important cofactor in cellular transmethylation reactions.
Homocysteine is a by-product formed in the biologic transmethylation reactions and detoxified with the methionine synthetase, which is the enzyme depending on vitamin B12, B6, and folate as coenzymes for proper functioning S-adenosylmethionine and methylation.
Both an increase in SAH levels and a decrease in the SAMe-to-SAH ratio can inhibit transmethylation reactions (Lu 2000).