An investigation of processes that occur during the rebinding of carbon monoxide to myoglobin

The binding of small ligands to myoglobin at room temperature appears to be a simple, one-step process. However, experiments performed over a large range in time and temperature have shown that the situation is much more complex. Between 60 K and 160 K, the rebinding kinetics are non-exponential in time and are described by a distribution of enthalpy barriers, g(H), between a bound and pocket state. Above 160 K, the structure of the low-temperature photoproduct of myoglobin relaxes towards the deoxy structure. The relaxation increases the enthalpy barriers for rebinding at the heme, and the rebinding kinetics slow down. Above 200 K, ligands can escape to the solvent, and the rebinding process becomes more complicated. Four peaks can be seen in the distribution of lifetimes in the dissociated state, f(log $\tau$): peaks I, 2, 3, and S. Peaks I and S are well understood. Peak I arises from rebinding to the unrelaxed or relaxing g(H) distribution. Peak S is the only process with rates that depend on the concentration of CO in the solvent and, therefore, represents ligands that have rebound from the solvent. Peaks 2 and 3 are geminate processes, but their cause is not yet unambiguously determined.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics, Molecular

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Lamb, Don Carroll

Contributors dc:contributor

• Frauenfelder, Hans

• Physics, Molecular
• Biophysics, General

Statement dc:rights

• Copyright 1993 Lamb, Don Carroll

Language dc:language

eng

Identifier

AAI9329090
(UMI)AAI9329090

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/23551