| Popis: |
Interest in the crystal structure of a copper complex of the growth factor, glycyl-L-histidyl-L-lysine has been stimulated by the tripeptide's ability to facilitate copper uptake in cultured hepatoma cells and by the copper complex's tendency to induce angiogenesis. The coordination polyhedron is a distorted square pyramid, CuN3O2, with the four basal ligating atoms bonded to the copper at about 2.00 A and the apical ligating atom at 2.49 A. One tripeptide furnishes three of the basal atoms, the glycine amino nitrogen atom, the peptide nitrogen atom of the histidine, and the imine nitrogen atom of the imidazole. A second tripeptide is involved via its terminal carboxyl oxygen atom while the fifth copper ligand is a carboxyl oxygen atom of a third tripeptide. The carboxyl oxygen atoms form bridges between copper centers and thus the system is polymeric in the solid state. The crystal structure can be used to propose a model for the first step in the transport of copper into cells via a copper-tripeptide complex. |
