Informazioni e biochimica degli acidi folici
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Homepage > Biochemistry > Biosynthesis of p-aminobenzoic acid

Biochemistry:Biosynthesis of p-aminobenzoic acid


The acid p-amino benzoic acid or pABA is not synthesized in vertebrates; enzymes and, consequently, the pathways are only present in prokaryotes and in plant cells. The three precursors of p-amino benzoic acid, in order of distance from the pathway are the eritrosio, chorismate and pyruvate.

The pentose phosphate pathway leads to the formation of eritrosio-4-phosphate, a sugar aldotetrose who, along with phosphoenolpyruvate from glycolysis, goes to the metabolic pathway of the shikimate[5]. The chorismate is the end product of the shikimate pathway and is the essential precursor for the biogenesis of p-amino benzoic acid (4); generally speaking the shikimate pathway is a pathway for the synthesis of a large number of compounds, particularly aromatic with biological functions, such as important antioxidants (5).

In E. coli, p-amino benzoic acid is synthesized in a series of two enzymatically catalyzed reactions (6) starting from chorismate and L-glutamine. The enzymes involved are called pabA, pabB and pabC (Figure 3).

Biosintesi acido para-aminobenzoico


Figure 3 the formation of p-amino benzoic acid by chorismate

In plants, p-amino benzoic acid is synthesized in the chloroplast, and transported in mitochondria where it is used for folate biosynthesis. Most of the acid is, however, present in glycosylated (glu-pABA) form at the level of the vacuole, where is preserved (Figure 4).