Biosynthesis of Folate Coenzymes in Riboflavin-deficient Rats

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Abstract
The effects of riboflavin deficiency on folic acid metabolism, particularly on distribution of liver folate coenzymes and on enzymic activities involved in the synthesis of these structures, were studied. In the liver of riboflavin-deficient rats the storage of folate derivatives, and in particular of the reduced forms, is lower than that in control rats. Furthermore in the same experimental conditions, H4 folate dehydrogenase, the enzymic activity responsible for the overall conversion of folate to H4 folate and HCO-H4 folate synthetase, are markedly decreased. On the other hand, no significant differences were observed in the liver levels of serine hydroxymethyl transferase and 5,10-CH2-H4 folate dehydrogenase. The results demonstrate the influence of riboflavin on the utilization of folic acid for the biosynthesis of coenzymic derivatives. Such influence occurs mainly in the reduction steps responsible for the conversion of folate to H4 folate.