Tuning the selectivity and reactivity of metal-substituted polyoxometalates as artificial proteases by varying the nature of the embedded Lewis acid metal ion

The hydrolysis of horse heart cytochrome c (cytC) protein by two isostructural Keggin-type polyoxometalates (POMs), (Me2NH2)10[Ce(α-PW11O39)2] (Ce1–K2) and (Et2NH2)10[Zr(PW11O39)2] (Zr1–K2), which differ in the nature of the embedded Lewis acid metal ion, has been investigated. In the presence of Ce1–K2, selective hydrolysis of cytC was observed at the Trp60-Lys61 and Gly78-Thr79 peptide bonds at pH 7.4 and 37 °C. However, the isostructural Zr1–K2 exhibited a lower reactivity and different selectivity, cleaving cytC at the Asp3-Val4, Asp51-Ala52 and Gly78-Thr79 peptide bonds. Different spectroscopic techniques were used to verify the molecular interactions between cytC and each metal-substituted Keggin POM to elucidate the role of the Lewis acid metal ion in directing the selectivity of protein hydrolysis.status: publishe