Metabolic functions of vitamin B6
Pyridoxal phosphate is a coenzyme in three main areas of metabolism:
● in a wide variety of reactions of amino acids, espe-cially transamination, in which it functions as the intermediate carrier of the amino group, and decar-boxylation to form amines
● as the cofactor of glycogen phosphorylase in muscle and liver, where it is the phosphate group that is catalytically important
● in the regulation of the action of steroid hormones. Pyridoxal phosphate acts to remove the hormone–receptor complex from DNA binding, and so ter-minate the action of the hormones. In vitamin B6 deficiency there is increased sensitivity and respon-siveness of target tissues to low concentrations of steroid hormones, including estrogens, androgens, cortisol, and vitamin D.