Regioselective protein oxidative cleavage enabled by enzyme-like recognition of an inorganic metal oxo cluster ligand

Oxidative modifications of proteins are key to many applications in biotechnology. Metal-catalyzed oxidation reactions efficiently oxidize proteins but with low selectivity, and are highly dependent on the protein surface residues to direct the reaction. Herein, we demonstrate that discrete inorganic ligands such as polyoxometalates enable an efficient and selective protein oxidative cleavage. In the presence of ascorbate (1 mM), the Cu-substituted polyoxometalate K-8[Cu2+(H2O)(alpha(2)-P2W17O61)], ((CuWD)-W-II, 0.05 mM) selectively cleave hen egg white lysozyme under physiological conditions (pH =7.5, 37 degrees C) producing only four bands in the gel electropherogram (12.7, 11, 10, and 5 kDa). Liquid chromatography/mass spectrometry analysis reveals a regioselective cleavage in the vicinity of crystallographic (CuWD)-W-II/lysozyme interaction sites. Mechanistically, polyoxometalate is critical to position the Cu at the protein surface and limit the generation of oxidative species to the proximity of binding sites. Ultimately, this study outlines the potential of discrete, designable metal oxo clusters as catalysts for the selective modification of proteins through radical mechanisms under non-denaturing conditions. Metal-catalysed oxidation of proteins varies in selectivity and depends on the surface residues to direct the reaction. Here, the authors use polyoxometalate clusters as inorganic ligands for Cu ions, enabling the regioselective oxidative cleavage of a protein via reactive oxygen species in the vicinity of its binding sites.

Automated summary

Oxidative modifications of proteins play a crucial role in biotechnology, and metal-catalyzed oxidation reactions have low selectivity. However, the use of discrete inorganic ligands such as polyoxometalates enables efficient and selective protein oxidative cleavage by directing the reaction to specific sites on the protein surface.