Monoglutamate folate

J. R. Bertino, P. F. Nixon, and A. Nahas, Mechanism of uptake of folate monoglutamates and their metabolism. In Folic Acid Biochemistry and Physiology in Relation to Human Nutrition Requirements, National Academy of Sciences, Washington, D. C. 1977, p. 178. 

LT Vahteristo, V Ollilainen, P Varo. Liquid chromatographic determination of folate monoglutamates in fish, meat, egg, and dairy products consumed in Finland. J AOAC Int 80 373-378, 1997. 

LT Vahteristo, V Ollilainen, PE Koivistoinen, P Varo. Improvements in the analysis of reduced folate monoglutamates and folic acid in food by high-performance liquid chromatography. J Agric Food Chem 44 477-482, 1996. 

Occasionally, protein hinding of a vitamin on foods increases its absorption and hence its biological availability. For example, folate from milk is considerably better absorbed than that from either mixed food folates or free folic acid (Section 10.2.1). Folate bound to a specific binding protein in milk is absorbed in the Ueum, whereas free folate monoglutamate is absorbed in the (smaller) jejunum... 

Because conjugase is a zinc metallo-enzyme, zinc deficiency can impair the absorption of conjugated food folates, but not folate monoglutamate. 

Conjugase responds rapidly to zinc depletion and repletion, and it has been suggested that the absorption of a test dose of folate polyglutamates may provide a sensitive index of zinc nutritional status (Canton and Cremin, 1990). The absorption of folate monoglutamates (from pharmaceutical preparations or foods) is not affected. 

Scrum contains folate monoglutamates. The normal level of serum folate is 6-0 ng/ml or greater. A value of 3.0 ng/ml or less indicates a folate deficiency. Scrum folate levels are sensitive to recent dietary practices aitd hence may not accurately reflect the amount of folate in tissues. True folate status is closely related to the tissue or cellular level of folate, rather than the serum level. 

Folylpoly-7-glutamate hydrolase catalyzes the hydrolysis of the polyglutamate peptide from intracellular folate-generating folate monoglutamate (135), which can be transported out of the cell." The pteridine ring of the tetrahydrofolate (135) undergoes sequential oxidation to dihydrofolate (137) and... 

The findings of Stephens et al. (SI9) were similar, but they also reported that if tissues are saturated with folate before testing, folate polyglutamate absorption, as measured by rises in serum folate monoglutamate, was of the same degree in women using oral contraceptives and in those who were nonusers. 

Gregory, J. F., and Toth, J. P. (1988a). Chemical synthesis of deuterated folate monoglutamate and in vivo assessment of urinary excretion of deuterated folates in man. AnaL Biochan. ITU, 94-104. 

Stokes, P. and Webb, K. 1999. Analysis of some folate monoglutamates by high-performance hquid chromatography-mass spectrometry. I. J. Chromatogr. A. 864 59-67. 

The biochemical functions of folate were first determined with bacteria. Folate plays a major role in carrying one-carbon units within cells. In the brush border of mucosal cells, the polyglutamyl chain is removed by the enzyme folate conjugase and folate monoglutamate is subsequently absorbed. Folate acts as both a donor and receiver of one-carbon moieties in a variety of reactions. 

Folate polyglutamates are the preferred substrates for folate-dependent enzymes they are more active metabolically in cells and also better retained in cells than folate monoglutamates. Natural folates found in foods are all conjugated to a polyglutamyl chain containing different numbers of glutamic adds depending on the type of food. 

Kohashi, M., Inoue, K., Sotobayashi, H., and Iwai, K., 1986. Microdetermination of folate monoglutamates in serum by liquid-chromatography with electrochemical detection. Journal of Chromatography. 382 303-307. 

Table 1 Comparison of Detection Limits for Various HPLC and Microbiological Methods Used for Determination of Folate Monoglutamates in Foods and Biological Samples (ng per Injection)... 

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