Myoglobin Microsperes and Metalloporphyrin -Peptide Complexes
Rosenblatt, Michael Maurice
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https://hdl.handle.net/2142/84495
Description
Title
Myoglobin Microsperes and Metalloporphyrin -Peptide Complexes
Author(s)
Rosenblatt, Michael Maurice
Issue Date
2000
Doctoral Committee Chair(s)
Kenneth S. Suslick
Department of Study
Chemistry
Discipline
Chemistry
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Chemistry, Analytical
Language
eng
Abstract
Addition of disulfide bridges and ionic contacts. We have synthesized and characterized a new class of heme-peptide complexes using disulfide-linked tweezers and cyclic peptides. The binding affinities, helicities, and mechanism of binding of linear, tweezers, and cyclic peptides to [Fe III(coproporphyrin-I)]+ have been determined. We have incorporated disulfide bridges between amphiphilic peptides to make tweezers---and even cyclic-peptides that bind heme extremely strongly, roughly 5 x 106 times more strongly than histidine itself. CD studies show that the cyclic peptide heme complexes are completely a-helical. Paramagnetic NMR shows that the 15-mer peptides bind sequentially, with an observable mono-peptide, high-spin intermediate. In contrast, the cyclic peptide complexes ligate both imidazoles cooperatively to the heme, producing only a low spin complex. Electrochemical measurements of the E1/2 of the FeIII(coproporphyrin-I) complexes of these peptides are all a fairly low potentials, ranging from -215 to -252 mV vs. NHE at pH 7. Addition of salt contacts to the design, resulted in the production of a highly helical complex. This peptide, bound to a diamagnetic and water soluble CoIII(coproporphyrin-I), has a stability toward denaturation of 3 kcal/mole.
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