METAL-BINDING PROPERTIES OF SYNTHETIC METALLOPROTEINS
Abstract (Summary)This dissertation describes the metal-binding properties of synthetic self-assembled metalloproteins. A family of the synthetic metalloproteins was prepared based on the de novo designed peptide C16C19-GGY having the sequence Ac-K(IEALEGK)2(CEACEGK)(IEALEGK)GGY-amide. This sequence is based on the IEALEKG heptad repeat known to form two-stranded á-helical coiled coils, but was modified to contain the Cys-X-X-Cys thiolato metal binding motif found in a variety natural of metalloproteins. This cysteine-containing random coil apopeptide is capable of binding a variety of soft metal ions such as, Cu(I), Cd(II), Ag(I), Hg(II), Au(I), and Pt(II) which results in the formation of a metal-bridged self-organized á-helical bundles. It has been shown that such binding produces metal-specific oligomerization states of the resulting metalloproteins: synthetic Cu(I), Ag(I), Au(I), and Pt(II)-metalloproteins have an oligomerization state which differs from the one predicted by original design. These inorganic cofactors not only induce peptide self-assembly, but direct and transform the oligomerization state of the peptide. This illustrates how the structures of metalloproteins may be controlled by the coordination chemistry of their inorganic cofactors. A 1:1 metal:peptide stoichiometry is observed for the Cu(I) and Ag(I) adducts but the Cd(II) and Hg(II) complexes show a metal:peptide stoichiometry of 1:2. It is also shown that the Cu(I)-metalloprotein described here displays an intense room temperature long-lived (microsecond) luminescence at 600 nm. Such incorporated chemical functionality allows using this synthetic metalloprotein as a photoinduced electron-transfer agent in future studies.
School Location:USA - Ohio
Source Type:Master's Thesis
Date of Publication:01/01/2005