The Synthesis and Characterization of Model Complexes for the Metalloenzyme Quercetin Dioxygenase

Abstract

Metalloenzymes are proteins that catalyze a specific reaction and contain metals that are tightly bound at the active site. Dioxygenases, a subclass of metalloenzymes, transfer both oxygen atoms of O2 into substrate. They have the ability to cleave and degrade aromatic compounds and play an important role in many biological functions. Aromatic compounds are one of the most prevalent and persistent pollutants in the environment. Quercetin 2,3 Dioxygenase (QDO), is unique in that it is the only known dioxygenase that is copper dependent. The copper center is bound to three histidines, one glutamate, and the antioxidant quercetin. Bacillus subtilis is one of the known bacterial forms of QDO. The active site differs from the copper containing fungal form, Aspergillus japonicus, as first-row transition metals, such as Fe(II), Co(II), Zn(II), and Mn(II), can be coordinated.