Pteridine ring Pteroic acid

The pteroic acid moiety of tetrahydrofolate consists of a reduced pteridine ring and p-aminobenzoic acid. Folate from the diet is absorbed by the intestinal mucosa and in two enzymatic steps is reduced to tetrahydrofolate which is the active form of the coenzyme. Mammals cannot synthesize folate this normally does not present a problem because microorganisms of the intestinal tract readily do so. 

Folic acid is a conjugated molecule consisting of a pteridine ring structure linked to para-aminobenzoic acid (PABA) that forms pteroic acid. 

Folate and folic acid are generic terms for a family of compounds that function as coenzymes in the processing of one-carbon units and that are derived from pteroic acid (Pfe), to which one or more molecules of glutamic acid are attached. Pteroic acid is composed of a pteridine ring joined to a p-aminobenzoic acid residue (Figure 30-20). In basic solution, this substance has absorption maxima at 256, 282, and 365 nm and is fluorescent. When pteroic acid is conju-... 

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