Myoglobin Microsperes and Metalloporphyrin -Peptide Complexes

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.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Chemistry

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Rosenblatt, Michael Maurice

Contributors dc:contributor

• Kenneth S. Suslick

• Chemistry, Analytical

Language dc:language

eng

Identifier

(MiAaPQ)AAI9990126

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/84495