Folic acid biochemical function

Folic acid and its metabolites called folates are essential to the cell s functions. They act as coenzymes in many biochemical processes. Folate-dependent enzymes are vital to rapidly dividing cell populations, such as the neoplastic or normal-stem cells. Therefore, they are a target for anti-folates in anti-cancer treatment. 

Most vitamins function either as a hormone/ chemical messenger (cholecalciferol), structural component in some metabolic process (pantothenic acid), or a coenzyme (phytonadi-one, thiamine, riboflavin, niacin, pyridoxine, biotin, folic acid, cyanocobalamin). At least one vitamin has more than one biochemical role. Vitamin A as an aldehyde (retinal) is a structural component of the visual pigment rhodopsin and, in its acid form (retinoic acid), is a regulator of cell differentiation. The precise biochemical functions of ascorbic acid and a-tocopherol still are not well defined. 

Thymidylate synthetase is an important enzyme, which is responsible for the reductive methylation of deoxyuridylic acid (dUMP, 7) to deoxythymidylic acid (dTMP, 8). The methylation of the uracil moiety (present in RNA) to 5-methyl uracil (thymine, present in DNA) requires participation of a folic acid coenzyme, N, methylenetetrahydrofolate as a methyl donor. The functioning of thymidylate synthetase is coupled with the activity of DHF reductase. That is why this biochemical target is usually referred to as thymidylate synthetase/ DHF reductase. 

Jaenicke, L. Vitamin and coenzyme function Vitamin Bj2 and folic acid. Annu. Rev. Biochem. 33, 287-312 (1964)... 

Vitamins have diverse biochemical and physiological functions. Most vitamins e.g. the B complex vitamins) function as precursors for enzyme cofaetors, which help enzymes in their work as catalysts in the metabolism. In this role, vitamins may be tightly bound to enzymes as part of prosthetic groups. Vitamins may also be less tightly bound to enzyme catalysts as coenzymes i.e. detachable molecules that carry chemical groups or electrons between molecules) such as folic acid, which carries various forms of carbon groups—methyl, formyl and methylene— in the cell (Fenech 2001). 

FUNCTIONS. The specific biochemical functions of vitamin C are not clearly understood. Nevertheless, it is established as a very important substance for body welfare because of being implicated in the following roles (1) formation and maintenance of collagen, which makes for more rapid and sound healing of wounds and burns (2) metabolism of the amino acids tyrosine and tryptophan (3) absorption and movement of iron (4) metabolism of fats and lipids, and cholesterol control (5) as an antioxidant in the protection of vitamins A and E and the polyunsaturated fatty acids (6) sound teeth and bones (7) strong capillary walls and healthy blood vessels (8) metabolism of folic acid and perhaps in a number of other roles. Details follow ... 

A particularly active field of biochemical research deals with the manner in which folic add functHms in intomediary metabolism as a corollary of such studies has come knowledge of the conversion of foUc add to its functional forms. It was recognized eariy that folic acid must be concerned in some manner with the biosynthesis of purine bases and thymine. Later it was also shown to be involved in the formation of methionine, serine, and histidine. Subsequently it was learned that folic acid was the carrier of a single-carbon unit needed at a point in the synthesis of these metabo-... 

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