Date of Award

1-1-2009

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

College/School/Department

Department of Chemistry

Content Description

1 online resource (ix, 99 pages) : illustrations (some color)

Dissertation/Thesis Chair

Charles P Scholes

Committee Members

Li Niu, Alexander Shekhtman, Carla Theimer, Keith Earle

Keywords

Cytochrome c’, Electron Nuclear Double Resonance (ENDOR), Iso-1-Cytochrome c, Nitric oxide (NO), Soluble Guanylate Cyclase, Spin labeled folding, Cytochrome c, Nitric oxide

Subject Categories

Physical Chemistry

Abstract

Cytochrome c’ binds and transfers endogenous NO in the denitrifying variant of Rhodobacter sphaeroides 2.4.3 and the NO bound ferrous heme that forms 5-coordinate resembles regulatory site in soluble guanylate cyclase. The Arg127 is close to the 5-coordiate NO bound heme of the cytochrome c’. The mutant (R127A) that was overexpressed in a cytochrome c’ knock-out R. sphaeroides 2.4.3 provided the opportunity to research the functional role of Arg127 in the redox potential and NO binding. The mutant (R127A) showed lower redox potential and lower NO binding free energy than wild type. ERP and ENDOR showed that the mutant had less value of 14NO hyperfine coupling, which was closer to that of a 5-coordinate NO-heme model. Deuterium hyperfine coupling of NO wild type that showed the possibility of the hydrogen bonding with the O of the NO, disappeared at the mutant (R127A) with uncharged Ala127. Therefore wild type cytochrome c’ with Arg127 has a higher NO dissociation constant for the NO bound heme and keeps the internal NO physiological micromolar concentration in the cell. The wild type with Arg127 provides a higher redox potential to favor the ferrous heme form for NO binding.

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