Rate of hydrolysis of the phosphate esters of B vitamins is reduced by zinc deficiency: In vitro and in vivo.

Extracellular hydrolysis of the phosphate esters of B vitamins (B1, B2, and B6) is crucial for their cellular uptake and metabolism. Although a few zinc-dependent enzymes have been implicated in these processes, their exact mechanisms of action remain largely unknown. This study investigated the potential involvement of phosphate group hydrolyzing enzymes in the hydrolysis of B vitamin phosphate esters. We evaluated enzyme activity in membrane lysates prepared from cells transiently transfected with these enzymes or those endogenously expressing them. Specifically, we investigated how zinc deficiency affects the rate of hydrolysis of B vitamin phosphate esters in cellular lysates. Assessment of the activities of zinc-dependent ectoenzymes in the lysates prepared from cells cultured in zinc-deficient conditions and in the serum of rats fed zinc-deficient diets revealed that zinc deficiency reduced the extracellular hydrolysis activity of B vitamin phosphate esters. Furthermore, our findings explain the similarities between several symptoms of B vitamin and zinc deficiencies. Collectively, this study provides novel insights into the diverse symptoms of zinc deficiency and could guide the development of appropriate clinical strategies.