FIG 1.

PLP biosynthesis and salvage. In S. enterica, PLP can be synthesized de novo via the DXP-dependent pathway (black box) or salvaged from other B₆ vitamers (green box). Other organisms, such as Saccharomyces cerevisiae, use the DXP-independent pathway (blue box) to synthesize PLP in addition to salvage. Animals, including humans, lack the biosynthetic pathway and rely exclusively on salvage to acquire this cofactor. Relevant enzymes involved in biosynthesis and salvage of PLP are shown next to the arrows, each of which represents a biochemical reaction catalyzed by the corresponding enzyme.