Hydrolysis of glucose-6-phosphate in aged, acid-forced hydrolysed nanomolar inorganic iron solutions—an inorganic biocatalyst?

Abstract

Phosphate ester hydrolysis is one of the most important chemical processes in biological systems. Although catalysis by the natural phosphoesterases, e.g., purple acid phosphatase (PAP) and its biomimetics, are well known in biochemistry, it has been reported that some metals and mineral phases can significantly facilitate the hydrolysis of phosphate ester. Here we report for the first time that aged, acid-forced hydrolysed nanomolar inorganic iron solutions significantly promoted the hydrolysis of glucose-6-phosphate (G6P), and that the reaction kinetics followed the Michaelis–Menten equation. The catalysis was inhibited by tetrahedral oxyanions in an order of WO₄ > MoO₄ > PO₄. The newly formed oxo-bridge or hydroxo-bridge during the iron-aging process might contribute to this biocatalytic effect, though the detailed mechanism is still unclear. Further studies are needed in order to understand the (hydr)oxo-bridged Fe–Fe structure in water and its role in organic phosphorus transformation. This catalyst might be one of many ubiquitous sets of inorganic enzymes yet to be discovered in nature that act as a bridge between the inorganic and organic worlds, and would have played a critical role in the origin of life.