Folic Coenzymes in Catabolism

A vitamin may participate in synthesizing cellular catalysts and in degrading major substrates. Assumingi that the turnover numbers—the wear and tear—of the vitamin as well as the enzyme affinities are about the same for both activities, then a major substrate reaction should demand much more folic enzyme than would the syntheses of quantitatively minor cell constituents. Substrates dissimilated anaerobically would be especially favorable for study when a Ci unit is concerned autoxidative destruction of folic enzymes is minimal. Clostridial fermentations, as will be seen, have furthered folic studies remarkably. 

Formylglutamic acid can be formed in liver in the readily reversible reaction (Silverman et al, 1958b) 5-formyl-FH4 + glutamic acid FH4-N-formylglutamic acid, a reaction also observed by Miller and Waelsch (1957). 

Glycine degradation by bovine spermatozoa is thought to go through glyoxylate, formate, and CO2 (Flipse and Benson, 1957). A folic coenzyme, if required here, should be extraordinarily interesting Does the spermatozoon retain the folic coenzyme used in the synthesis of its DNA  

Bacteria can make formate in many ways. A preliminary note by Chin et al. (1957) reports that the phosphoroclastic splitting of pyruvate to HCOOH -h CH3COOH by Escherichia coli was stimulated by FH4. Huen-nekens et al. (1958) refer to similar unpublished results (Whitely, 1958) with Micrococcus aerogenes and M, lactilyticus-, serine was not an intermediate. If the reaction HCOOH H2 + CO2, also carried out by E. coli, turns out to be folic-catalyzed, the presumption would be greatly strengthened that all formate-C02 reactions require FA, as might perhaps also formate-oxalate reactions. 

Formiminoglutamic acid (FGA) accumulates in the urine of folic-deficient animals because of the blocking of the FH -mediated reaction needed for its 

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