The characterisation and catalytic properties of biomimetic metal-peptide complexes immobilised on mesoporous silica

The active core of the enzyme methane mono-oxygenase (MMO) contains an iron (or copper) dimer with histidine and glutamic acid ligands located on a His-x-x-Glu sequence of the peptide chain. We mimicked the active core of MMO by immobilising the His-Gly-Gly-Glu motif on a silica support, using the methods of solid phase peptide synthesis, and by allowing complexes with Cu and Fe cations to self-assemble. The dominating mode of coordination in the complexes was elucidated by a group fitting analysis of the extended X-ray absorption fine structure (EXAFS) spectra. The complexation of the metal cations by the short peptide significantly changed (improved) their catalytic properties in the oxidation of cyclohexane by H2O2 or by 3-chloro-perbenzoic acid.