Active Site Ligand Interactions in Galactose Oxidase

Abstract

Redox catalysis by metalloenzymes displays a remarkable diversity in chemistry and in catalytic structures. The highly evolved catalytic active sites revealed by recent spectroscopic^1–4 and crystallographic^5–8 studies serve as an inspiration to synthetic chemists turning from design of molecular architecture to the engineering of functional molecules. Key catalytic principles on which this type of biomimetic complex can be built are presently emerging from active site studies on metalloenzymes, using approaches that probe the reaction mechanisms for the biological metal complexes. X-ray crystallography now routinely reveals structures of metalloenzyme active sites at near atomic resolution, establishing the geometric features with unparalleled accuracy. However, crystallographic data is still low resolution compared to the electronic level of detail that relates directly to the origins of chemical reactivity. Spectroscopy provides the essential link between the geometric factors revealed by crystallography and theelectronic structures of metalloenzyme active sites. This role for spectroscopic studies, bridging between geometric and electronic structural descriptions, is particularly well represented by active site spectral studies on the fungal enzyme galactose oxidase.