a deeper insight
L-Methionine Reduces Oxidant Stress in Endothelial Cells: Role of Heme Oxygenase-1, Ferritin, and Nitric Oxide
Dietary methionine effects on plasma homocysteine and HDL metabolism in mice.2007
Methionine and dermatitis
Homocysteine --> methionine
from Serine, glycine and one-carbon units: cancer metabolism in full circle, 2013
OA fulltext
CH3MTHF (5-methyltetrahydrofolate-homocysteine methyltransferase (EC:2.1.1.13[]=Homo+sapiens&show_tm=0))
Betaine (betaine--homocysteine S-methyltransferase (EC:2.1.1.5))
Evidence for direct methyl transfer in betaine: homocysteine S-methyl-transferase. 1983
We described recently the purification and preliminary characterization of human hepatic betaine: homocysteins S-methyltransferase where it was shown that isovalerate and 3,3-dimethylbutyrate, analogs of dimethylglycine and betaine, respectively, were good inhibitors. ...omissis...*These findings support the hypothesis that methyl transfer in this enzyme occurs directly from one substrate to the other.*
Methionine Exposure Alters Glutamate Uptake and Adenine Nucleotide Hydrolysis in the Zebrafish Brain. 2016
Hypermethioninemic patients may exhibit different neurological dysfunctions, and the mechanisms underlying these pathologies remain obscure. Glutamate and ATP are important excitatory neurotransmitters co-released at synaptic clefts, and whose activities are intrinsically related. Adenosine-the final product of ATP breakdown-is also an important neuromodulator. Here, we investigated the effects of long-term (7-day) exposure to 1.5 or 3 mM methionine (Met) on glutamate uptake in brain tissues (telencephalon, optic tectum, and cerebellum) and on ATP, ADP, and AMP catabolism by ecto-nucleotidases found in brain membrane samples, using a zebrafish model. Also, we evaluated the expression of ecto-nucleotidase (ntdp1, ntdp2mg, ntdp2mq, ntdp2mv, ntdp3, and nt5e) and adenosine receptor (adora1, adora2aa, adora2ab, adora2b) genes in the brain of zebrafish exposed to Met. In animals exposed to 3.0 mM Met, glutamate uptake in the telencephalon decreased significantly. Also, ATP and ADP (but not AMP) catabolism decreased significantly at both Met concentrations tested. The messenger RNA (mRNA) levels of ntpd genes and of the adenosine receptors adora1 and adora2aa increased significantly after Met exposure. In contrast, adora2ab mRNA levels decreased after Met exposure. Our data suggest that glutamate and ATP accumulate at synaptic clefts after Met exposure, with potential detrimental effects to the nervous system. This phenomenon might explain, at least in part, the increased susceptibility of hypermethioninemic patients to neurological symptoms.
