Determination of copper binding sites in peptides containing basic residues: a combined experimental and theoretical study

The energetics of monodentate Cu+ binding to model systems representing amino acid side chains and bidentate Cu+ binding in amino acid residues are investigated using electronic structure methods. Results from these calculations are compared with mass spectral data to determine Cu+ binding sites for gas-phase [M+Cu](+) peptide ions. Calculated monodentate Cu+ binding energies for amino acid models predict a relative Cu+ affinity ordering: arg > his > lys > cys > ser, whereas bidentate Cu+ binding energies give a relative Cut affinity ordering of arg > lys > his > gin > asn > glu> asp. Calculated results are in agreement with current and published experimental results. (C) 2001 Elsevier Science B.V.