| Autor: |
Lau, Show-Jy, Kruck, Theo P.A., Sarkar, Bibudhendra |
| Zdroj: |
Journal of Biological Chemistry; September 1974, Vol. 249 Issue: 18 p5878-5884, 7p |
| Abstrakt: |
Diglycyl-l-histidine is a peptide molecule designed to mimic the specific Cu(II) transport site of human albumin. The equilibria involved in the Cu(II)-diglycyl-l-histidine system have been investigated by analytical potentiometry in aqueous solution (0.15 mNaCl, 25°). The synthetic peptide molecule bound Cu(II) exclusively as a 1:1 complex in the pH range of 6.50 to 11.00. The results further showed that the complex has the same ligand atoms binding to Cu(II) as those suggested for the specific Cu(II) binding site of human albumin. The interaction of peptide with Cu(II) in the presence of albumin, studied by equilibrium dialysis at pH 7.53 and ionic strength 0.16, indicates that this tripeptide is able to compete with albumin for Cu(II). The dissociation constant of the Cu(II)-peptide complex has a value of 1.18 x10-16as compared with 6.61 x10-17for Cu(II)-albumin. The lower Cu(II) binding strength of the peptide may reflect the influence of either the COOH-terminal free carboxyl group of the peptide or the side chain residues of the Cu(II) binding site in the native protein or both. In the presence of equimolar concentrations of albumin and peptide, and approximately 20-fold excess of l-histidine, there is about 18% of Cu(II) present in the forms of Cu(II)-albumin and l-histidine-Cu(II)-albumin, 36% in the forms of Cu(II)-peptide and l-histidine-Cu(II)-peptide, and 46% as Cu(II)-l-histidine2. The biomedical implications of designing a small molecule to mimic certain functions of a biologically important macromolecule are discussed. |
| Databáze: |
Supplemental Index |
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