Studies on transition-metal–peptide complexes. Part 7. Copper(II) complexes of dipeptides containingL-histidine
- 1 January 1982
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc., Dalton Trans.
- No. 11,p. 2159-2163
- https://doi.org/10.1039/dt9820002159
Abstract
The copper(II) complexes of three dipeptides (HA) containing L-histidine residues [L-carnosine, L-histidylglycine (HisGly), and glycyl-L-histidine (GlyHis)] have been studied by pH-metric, spectrophotometric, and, in part, 1H n.m.r. and calorimetric methods. With L-carnosine and HisGly, the formation of a dimeric complex [Cu2A2H–2] was found, in which the co-ordination of copper(II) is glycylglycine-like, while the fourth co-ordination site is occupied by the imidazole N3 nitrogen atom, forming a bridge between two copper(II) ions. An excess of HisGly suppresses the deprotonation of the peptide linkage and the complex [CuA2] is formed with histidine-like co-ordination. It is found that deprotonation of the peptide group is the easiest in the copper(II) complexes of GlyHis. The effect of co-ordination on deprotonation of the pyrrole-NH group is discussed.Keywords
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