Peptide Models for Type III Copper Sites in Proteins

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DESCRIPTION (provided by applicant): The proposed study involves examining the binding sites of copper (I) and copper (ll) in three peptides with a view to establishing the coordination environment of the metal ion. In the first stage of the project, the solution conformation of the prepared peptides will be examined with and without the presence of copper (I) and copper (ll) ions in order to establish the extent of conformational change that is necessary for complexation of copper. The binding sites of copper in the copper-peptide complexes will be further determined with EPR, ENDOR, ESEEM, NMR and FTIR spectroscopy. Two of the prepared peptides will be reacted with an appropriate copper salt in a 2:1 copper (I)/peptide ratio in order to produce a dicopper complex. The dicopper complex will be transformed into a dioxygen adduct through reaction with molecular oxygen. The dioxygen complex for each ligand will be investigated by the use of electronic absorption spectroscopy and NMR spectroscopy. Stability of the dioxygen complex towards water and other protic solvents will be examined. Physical studies, including X-ray structural analysis, are proposed for all isolated complexes of the oxy or deoxy forms.