Folic acid aspects

Cobalamin, 25 803 folic acid and, 25 802 Cobalt (Co), 7 207-228. See also Co-base superalloys 60Co isotope 60Co nucleus Fe-Ni-Co alloys Dicobalt octacarbonyl Tetracobalt dodecacarbonyl analysis, 7 215-216 in ceramic-matrix composites, 5 554t coke formation on, 5 266 colloidal suspensions, 7 275 economic aspects, 7 214-215 effect on copper resistivity, 7 676t environmental concerns, 7 216 health and safety factors, 7 216-218 in M-type ferrites, 11 66, 69 occurrence, 7 208... 

Coenzyme A (CoA), 20 249—250. See also Ace to acetyl- Co A in citric acid cycle, 6 633 Coenzyme Q10, 17 673 Coercivity, ofM-type ferrites, 11 70 Coextruded food packaging, 18 44, 45 Coextrusion techniques, for gelatin capsule preparation, 11 549 Cofactors, 10 253 11 4 folic acid, 25 801-802 for enzymes, 3 672-673 protein, 20 828-829 vitamin B12, 25 804 vitamins as, 25 781 Coffea arabica, 7 250 Cojfea Canephora, 7 250 Coffea liberica, 7 250 Coffee, 2 108 6 366 7 250-271 biotechnology, 7 265-267 decaffeinated, 7 263 economic aspects, 7 263-264 estimated maximum oxygen tolerance, 3 381t... 

The number of vitamin B 12-dependent reactions is not large. Most of these involve rearrangements of the carbon skeletons of metabolites. Such reactions are important in linking some aspects of fatty acid metabolism to the citric acid cycle. In another form, a vitamin Bi2-derived coenzyme is involved, along with folic acid coenzymes, in the metabolism of one-carbon fragments, including the biosynthesis of methionine. 

J. Ferre, F. Silva, M. D. Real, and J. L. Mensua, Chem. Biol. Pteridines, Proc. 7th Int. Symp. Pteridines Folic Acid Deriv., Chem. Biol. Clin. Aspects, Berlin, 1982, (J. A. Blair, ed.), p. 669 (1983). Berlin, 1982 (published in 1983). 

Coward, J. K. McGuire, J.J. Galivan, J. in Chemistry and Biology of Pteridines 1989. Pteridines and Folic Acid Derivatives. Proceedings of the Ninth International Symposium on Pteridines and Folic Acid Derivatives. Chemical, Biological and Clinical Aspects, Zurich, Switzerland, Sept 3-8, 1989 Curtius, H.-C. Ghisla, S. Blau, N Eds. dc Gruyter Berlin, 1990 pp 1198 1202. 

J.R. Piper, G.S. McCaleb, J.A. Montgomery and F.M. Sirotnak, 8th International Symposium on Pteridines and Folic Acid Derivatives Chemical, Biological and Clinical Aspects (June 15-20, 1986), Montreal, Canada. We thank Dr. J.R. Piper for providing us with a preprint of this work prior to publication. 

Some of the structural properties which have been ascribed to DA receptors appear to deserve attention for their heuristic value, but painfully few should engender much confidence in their reality. A sobering lesson is available from analysis of complexes of dihydrofolate reductase (], 8). Methotrexate is a very close analog of folic acid and is a potent inhibitor of the enzyme, but it is now almost certain that these ligands bind in the enzyme active site in aspects differing by a rota-... 

Aminopterin and amethopterin are 4-amino analogues of folic acid (Fig. 11.5) and as such are potent inhibitors of the enzyme dihydrofolate reductase (EC 1.5.1.3) (Blakley, 1969). This enzyme catalyses the reduction of folic acid and dihydrofolic acid to tetrahy-drofolic acid which is the level of reduction of the active coenzyme involved in many different aspects of single carbon transfer. As is clear from Fig. 11.6, tetrahydrofolate is involved in the metabolism of (a) the amino acids glycine and methionine (b) the carbon atoms at positions 2 and 8 of the purine ring (c) the methyl group of thymidine and (d) indirectly in the synthesis of choline and histidine. 

This knowledge subsequently initiated much work in isolating new natural pteridines as well as many synthetic approaches to this heterocyclic nucleus as exemplified by the vitamin folic acid and methotrexate, an antileukemia drug <49JA1753>. The importance of this interdisciplinary field was recognized as early as 1952 by Polonovski, who organized the first symposium. By 1995, 10 periodic international congresses and many more symposia on specific aspects of pteridines followed. 

Four of the amino acids, alanine, aspartate, glutamate, and serine, are formed by the transamination of their corresponding oxoacids. The other nonessential amino acids are then derived from these four amino acids. The syntheses of serine and tyrosine are described below because of either their importance in aspects of metabolism or their clinical significance the synthesis of serine is essential for folic acid metabolism, while deficiencies in the enzymes synthesizing tyrosine can lead to phenylketonuria. 

Eichholzer M, Luthy J, Moser U, Stahehn HB, Gutzwiller F. Sicherheitsaspekte der Folsaure fur die Gesamtbevolkerung. [Safety aspects of folic acid for the general population.] Schweiz Rundsch Med Prax 2002 91(l-2) 7-16. 

Reynolds E.H., 1979. Fohc acid, vitamin B and the nervous system historical aspects. In Botez, M.I., and Reynolds, E.H. (ed.) Folic Acid in Neurology, Psychiatry, and Internal Medicine. Raven Press, New York, USA, pp. 1-5. 

Fluoroquinolones, 12.250, 18.271 Fluorouracil, adverse reactions, 23.476 Folic acid, dietary supplementation, 19.369 safety aspects, 27.407 Formoterol, tolerance, 24.187 Fragrances, contact allergy, 20.149... 

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