5- Methyltetrahydro folate

Ramaekers VT, Hausler M, Opladen T, Heimann G, Blau N (2002) Psychomotor retardation, spastic paraplegia, cerebellar ataxia and dyskinesia associated with low 5-methyltetrahydro-folate in cerebrospinal fluid a novel neurometabolic condition responding to folinic acid substitution. Neuropediatrics 33 301-308... 

Nutrition The effect of warfarin therapy for 6 months on folate status has been studied in 114 patients, using measurements of erythrocyte folate and 5-methyltetrahydro-folate and plasma folate, total homocysteine, phylloquinone, vitamin B12, and methylmalonic acid [ll. There were significant falls in total erythrocyte folate and 5-methyltetrahydrofolate and a concurrent increase in plasma phylloquinone, attributed to altered vitamin K metabolism. 

One form of methionine synthase common in bacteria uses lV -methyltetrahydrofolate as a methyl donor. Another form of the enzyme present in some bacteria and mammals uses A/ -methyltetrahydro-folate, but the methyl group is first transferred to cobalamin, derived from coenzyme B12, to form methylcobalamin as the methyl donor in methionine formation. This reaction and the rearrangement of L-methyl-malonyl-CoA to succinyl-CoA (see Box 17-2, Fig. la) are the only known coenzyme Bi2-dependent reactions in mammals. In cases of vitamin B12 deficiency, some symptoms can be alleviated by administering not only vitamin B12 but folate. As noted above, the methyl group of methylcobalamin is derived from W -methyltetrahy-drofolate. Because the reaction converting the methylene form to the 7V -methyl form of tetrahydrofo-... 

Zhao, S. Y Ragsdale, S. W. A conformational change in the methyltransferase from Clostridium thermoaceticum facilitates the methyl transfer from (6S)-methyltetrahydro-folate to the corrinoid iron-sulfur protein in the acetyl-CoA pathway. Biochemistry, 1996, 35(7), 2476-2481. 

Buchanan and his collaborators [96] have studied the role of coenzyme B12 in methionine synthesis. They have demonstrated that methionine is synthesized by transfer of the methyl group of 5,10-methyltetrahydro-folate to homocysteine (see Folic Acid). 

All organisms have recycling pathtvays for byproducts arising from reactions involving SAM. One recycling pathway leads to hydrolysis products L-homocysteine 8 and adenosine catalyzed by SAH-hydrolase (pathway ii). Subsequently, homocysteine is methylated to build L-Met 7 catalyzed by Met synthase (also called L-homocystdne methyltransferase) with N5-methyltetrahydro folate as cofactor (pathway iii). 

Folate and five related compounds (tetrahydro-, 5-methyltetrahydro-, 5-fomtyl-tetrahydro-, 10-formyl-, and 10-formyldihydrofolate) were extracted fitom foods and analyzed on a Cjg column (A = 280 nm). A complex 20-min 95/5 - 90/10 water (33 mM phosphate bulfer at pH 2.1)/acetonitrile gradient was used [1118]. Elution was complete in 18min. Tetrahydropfolate was incompletely resolved from,coextracted materials. Calibration standards ran from 8 to lOOng/mL. 

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