Designed High Affinity Cu2+-Binding α-Helical Foldamer
| Autor: | David James Miller, Klaus Fütterer, Rudolf Konrad Allemann, Raymond Ravelli, Andrew J. Nicoll |
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| Rok vydání: | 2006 |
| Předmět: |
Models
Molecular chemistry.chemical_classification Protein Folding Circular dichroism Chemistry Stereochemistry Foldamer Peptide General Chemistry Biochemistry Protein Structure Secondary Catalysis Dissociation constant Colloid and Surface Chemistry Metalloprotein Peptides Protein secondary structure Copper Histidine Protein Binding Coordination geometry |
| Zdroj: | Journal of the American Chemical Society. 128:9187-9193 |
| ISSN: | 1520-5126 0002-7863 |
| Popis: | The design, synthesis, and characterization of a folded high-affinity metal-binding peptide is described. Based on the previously described folded peptide NTH-18, in which an alpha-helix was constrained through two disulfide bonds to a C-terminal extension of noncanonical secondary structure, a peptide (1) was designed to contain two histidine residues in positions 3 and 7. Air oxidation of 1 led to the formation of peptide 2, which contained two intramolecular disulfide bonds. The presence of the two histidines significantly destabilized the alpha-helical structure of 2 when compared to NTH-18. However, CD spectroscopy revealed that the addition of certain transition metal ions allowed the reformation of a stable alpha-helix. CD, NMR, and EPR spectroscopy as well as MALDI-TOF mass spectrometry indicated that 2 bound to Cu2+ to form a 1:1 complex via the imidazoles of the two histidine side chains. A glycine displacement assay revealed a dissociation constant for this complex of 5 nM at pH 8, which is the lowest reported value for a designed Cu2+-binding peptide. This peptide displayed more than 100-fold selectivity for Cu2+ over Zn2+, Ni2+, and Co2+. The 1.05 A crystal structure of the Cu(II)-complex of 2 revealed a square-pyramidal coordination geometry and confirmed that 2 bound to copper in an alpha-helical conformation via its two histidine side chains. The high affinity metal binding of peptide 2 demonstrates that metals can be used for the selective nucleation of alpha-helices. |
| Databáze: | OpenAIRE |
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