Free Energies of Electron Transfer, Electrochemical Properties, Electron Transfer Kinetic Theoretical and Quantitative Structural Relationship Studies of Cn@X-[HbA] (HbA=Hemoglobin A; X= - and -Fumarate Crosslinked Hemoglobins ( XL & XL)) Nanostructure Complexes

Abstract

The binding, release and oxidation of oxygen occur at the heme group iron ion. Hemoglobin<br />oxidation-reduction studies have been previously performed using spectroelectrochemistry (SEC) and<br />have provided insight into the hemoglobin electron transfer process and more specifically, into the<br />heme group electronic factor and subunit interaction influences. In this study, the number of fullerene<br />carbon atoms was used as an index to establish a relationship between the structures of hemoglobin A<br />and - and -fumarate crosslinked hemoglobins, which were designated as HbA, XL and XL-<br />[HbA] 1-3, respectively. These compounds represent the most well-known blood molecular systems<br />and fullerenes (Cn, where n = 60, 70, 76, 82 or 86), which generated the following complexes:<br />Cn@[HbA], A-1 to A-5; Cn@DXL-[HbA], B-1 to B-5 and Cn@EXL-[HbA], C-1 to C-5. The<br />relationship between the carbon atom number and electron transfer free energies ( Get) were assessed<br />using the Rehm-Weller equation for A-1 to A-5, B1 to B-5 and C-1 to C-5 supramolecular Cn@X-<br />[HbA] (where HbA = hemoglobin A; X = - and -fumarate crosslinked hemoglobins ( XL & XL))<br />and complexes 4-57, which possessed different electrochemical properties. Calculations were<br />presented for the first Cn oxidation potentials (Ox.E1). The results were used to calculate the electron<br />transfer first free energies ( Get(1)) of supramolecular complexes A-1 to A-5, B1 to B-5 and C-1 to C-<br />5 for fullerenes C60 to C300. The first free activation energies and kinetic rate constants of the electron<br />transfers, G#<br />et(n) ( Get(1)<br />#) and ket, respectively, were also calculated in this study for A-1 to A-7, B1<br />to B-7 and C-1 to C-7 (compounds 4-24) in accordance with the Marcus theory.