Pyridoxal phosphate (Vitamin B6 phosphate) is the active form of vitamin B6 and a coenzyme for many pyridoxal phosphate (PLP)-dependent enzymes. PLP is involved in numerous enzymatic transamination, decarboxylation and deamination reactions; it is necessary for the synthesis of amino acids and amino acid metabolites, and for the synthesis and/or catabolism of certain neurotransmitters, including the conversion of glutamate into gamma-aminobutyric acid (GABA) and levodopa into dopamine. PLP can be used as a dietary supplement in cases of vitamin B6 deficiency. Reduced levels of PLP in the brain can cause neurological dysfunction.

Pyridoxal phosphate 会立即降低 DNA 的合成速度。Pyridoxal 5′-phosphate 严重抑制 DNA 聚合酶和 RNase H。在各种酶/底物比率下，与Pyridoxal phosphate共轭的 NEIL2 的活性都比完整的酶低得多。Pyridoxal phosphate共轭后，NEIL2 完全丧失了与 THF 配体结合的能力。