Methyltetrahydrofolic acid

Table 6.3.1 Reference cerebrospinal fluid 5-methyltetrahydrofolic acid (5MTHF) values...

Belz S, Frickel C, Wolfrom C, Nau H, Henze G (1994) High-performance liquid chromatographic determination of methotrexate, 7-hydroxymethotrexate, 5-methyltetrahydrofolic acid and folinic acid in serum and cerebrospinal fluid. J Chromatogr Biomed Appl 661 109-118... 

Corona, G., Giannini, F., Fabris, M., Toffoli, G., and Boiocchi, M. (1998). Role of folate receptor and reduced folate carrier in the transport of 5-methyltetrahydrofolic acid in human ovarian carcinoma cells. Int. ]. Cancer 75(1), 125-133. 

The one-carbon unit required for the formation of the /8-carboline tricycle is derived from 5-methyltetrahydrofolic acid, a cofactor present in platelets ( ). This finding led to a diagnostic assay which allows for the measurement of the enzyme activity of human platelets in terms of their ability to produce, on addition of tryptamine, TBC 25. This alkaloid, when given to rats, led to two metabolites hydroxylated in the aromatic ring at C-6 and C-7, respectively (59). The formation of these metabolites may proceed via an arene oxide. 

Lankelma, J. VanDerKleijn, E. Jansen, M.J.T. Determination of 5-methyltetrahydrofolic acid in plasma and spinal fluid by high-performance liquid chromatography, using on-column concentration and electrochemical detection. J. Chromatogr. 1980, 182, 35 5. 

The (3R)- and (3S)-[3- Hi,3- Hi]serines 60, Hj, = H, H = H, and 60, H = H, Hj = H, respectively, were also used with the coupled enzymes serine hydroxymethyltransferase and methylenetetrahydrofolate reductase (EC 1.1.1.171) (100). Enzymic reduction of the labeled samples of the intermediate 5,10-methylenetetrahydrofolic acid 56b gave samples of 5-methyltetrahydrofolic acid 91 (Scheme 26). These were degraded to acetate by a sequence that involved one inversion of configuration, and assay of the acetates showed that the overall stereochemistry of the reduction was as in Scheme 26 (100). 

Excess NaBH4 in water added at room temp, under to a stirred soln. of folic acid in Tris buffer at pH 7.8, after 15 min. excess NaBH4 decomposed with 5 N acetic acid, the soln. adjusted to pH 7.8, aq. 37%-formaldehyde added immediately followed by excess NaBH4 in water, and kept 1 hr. at 45 in a slow Ng-stream 5-methyltetrahydrofolic acid. Y ca. 70%. J. A. Blair and K. J. Saunders, Anal. Biodiem. 34, 376 (1970). 

L-Methionine originates from L-homoserine, a product of L-aspartic acid metabolism (D 16). Key intermediates are 0-phospho-L-homoserine (plants) and 0-acyl-L-homoserine (microorganisms). Cystathionine is formed with L-cysteine as sulfur donor. It may be degraded to L-homocysteine, which, however, may also directly be formed with the participation of sulfide, a reaction resembling the formation of L-cysteine from 0-acetyl-L-serine (D 11). 5-Methyltetrahydrofolic acid acts as donor of the L-methionine methyl group (C 3.2). 

It was revealed previously that BCD was well-suited for the analysis of 5-methyltetrahydrofolic acid (5MeTHF) in plasma, in which only a relatively low voltage was required to attain a peak height (thus being fairly independent... 

Lucock, M.D., Hartley, R., and Smithells, R.W., 1989. A rapid and specific hplc-electrochemical method for the determination of endogenous 5-methyltetrahydrofolic acid in plasma using solid-phase sample preparation with internal standardization. Biomedical Chromatography. 3 58-63. 

Pawlosky, R.J., Flanagan, V.P., and Pfeiffer, C.M., 2001. Determination of 5-methyltetrahydrofolic acid in human serum by stable-isotope dilution high-performance liquid chromatography-mass spectrometry. Analytical Biochemistry. 298 299-305. 

A Schultz, K Wiedemann, I Bitsch. Stabilization of 5-methyltetrahydrofolic acid and subsequent analysis by reversed-phase high-performance liquid chromatography. J Chromatogi 328 417-421, 1985. 

Thomas PM, Flanagan VP, Pawlosky RJ. Determination of 5-methyltetrahydrofolic acid and folic acid in citrus juices using stable isotope dilution—mass spectrometry. J Agri Food Chem 2003 51 1293-6. 

The formidable-looking molecule 5-methyltetrahydrofolic acid (abbreviated 5-methyl-FH4) is the product of sequences of biological reactions that convert carbon atoms from a variety of simple molecules, such as formic acid and the amino acid histidine, into methyl groups. 

The simplest synthesis of 5-methyltetrahydrofolic acid is from tetrahydrofolic acid (FH4) and trimethylsulfonium ion, a reaction carried out by microorganisms in the soil. 

Figure 2.16 Reaction between 5-methyltetrahydrofolic acid and S-adenosylhomocysteine gives S-adenosylmethionine which can react with an alcohol, phenol, or carboxylic acid to give a methyl ether, a phenolic methyl ether or a methyl ester respectively, regenerating S-adenosylhomocysteine...

---