folic acid(redirected from Streptococcus lactis R factor)
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folic acid:see coenzymecoenzyme
, any one of a group of relatively small organic molecules required for the catalytic function of certain enzymes. A coenzyme may either be attached by covalent bonds to a particular enzyme or exist freely in solution, but in either case it participates intimately in
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group of organic substances that are required in the diet of humans and animals for normal growth, maintenance of life, and normal reproduction. Vitamins act as catalysts; very often either the vitamins themselves are coenzymes, or they form integral parts of coenzymes.
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(vitamin Bc, pteroylglutamic acid), a vitamin of the B group. One folic-acid molecule is composed of a pteridine nucleus and para-aminobenzoic and glutamic-acid residues. The pale yellow hygroscopic crystals, which decompose at 250°C, are poorly soluble in water (0.001 percent). Folic acid is widely distributed in nature and is present in all animal, plant, and bacterial cells. It is synthesized by most microorganisms and lower and higher plants. It is not formed in the tissues of man, mammals, and birds and therefore should be obtained through food; however, it may be synthesized by microflora in the intestines.
Folic acid stimulates hematogenic functions in the organism. In animal and plant tissues it takes part—in reduced form, that is, in the form of tetrahydrofolic acid and its derivatives—in the synthesis of purine and pyrimidine bases, certain amino acids (se-rine, methionine, histidine), choline, and other compounds. The adult daily folic-acid requirement is 0.2–0.4 mg. The primary sources of the vitamin are leafy vegetables, liver, and yeast; strawberries are also a rich source.
Folic acid is effective in the treatment of certain forms of anemia and other diseases. It is prepared by the condensation of 2, 4, 5-triamino-6-hydroxy pirimidine, 1,1, 3-trichloroacetone, and para-aminobenzoyl glutamic acid. Aminopterin and methotrexate, which have a structure similar to that of folic acid, are used in the treatment of certain types of malignant tumors. These compounds are antimetabolites of folic acid and have a suppressive effect on cell growth and development.
REFERENCESAndreeva, N. A. Vitaminy gruppy folievoi kisloty. Moscow, 1963.
Berezovskii, V. M. Khimiia vitaminov, 2nd ed. Moscow, 1973.
Vitaminy. Edited by M. I. Smirnov. Moscow, 1974.
Blakley, R. L. The Biochemistry of Folic Acid and Related Pteridines. Amsterdam-London, 1969
E. M. BIRINBERG