The objective is to understand the mechanism of biological electron transfer in molecular terms. Moreover, by the nature of the proposed studies a substantial understanding of biological specificity, the factors mediating protein-protein and protein-membrane interactions and structure-function relations in proteins will be obtained. Electron transfer and coupled energy conservation are fundamental to the life process thus an understanding of these phenomena is required if we are to fully understand the living cell. It is well established that driving force, electrostatics, distance/sterics, orientation, intervening media and protein dynamics all play a role in controlling the kinetics of electron transfer between molecules. In order to fully quantitate the role of each of these factors, we are proposing to exploit five specific redox proteins which have generally similar but distinct electron transfer properties. These systems were chosen as they each have different characteristics amenable to analysis in terms of the factors controlling biological electron transfer. The principal approaches are to use transient kinetics as an assay of function, interpretation of kinetics using available structural information and computer graphics, and using the techniques of molecular biology (site directed mutagenesis) to fully exploit these systems.
Our specific aims i nclude the following: a) characterization of examples of Class I c-type cytochromes (Rps. capsulata cytochrome c2), iron-sulfur proteins (white campion ferredoxin) and copper proteins (white campion plastocyanin) in terms of their interaction with physiological and non-physiological reactants to provide information on the factors mediating electron transfers in these systems, b) structural analysis of a group of high potential iron-sulfur proteins to obtain information on the control of oxidation-reduction potentials, protein folding, and phylogeny, c) characterization of cytochrome b/c1, from Rps. capsulata, an example of a complex (multichromophoric) membrane protein which will provide information on intracomplex electron transfer and interaction with cytochrome c2, and c) through comparison of the different protein studies derive a general understanding of biological electron transfer and the means to exploit other less well characterized systems.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM021277-16
Application #
3270384
Study Section
Physical Biochemistry Study Section (PB)
Project Start
1978-03-01
Project End
1992-03-31
Budget Start
1991-04-01
Budget End
1992-03-31
Support Year
16
Fiscal Year
1991
Total Cost
Indirect Cost
Name
University of Arizona
Department
Type
Schools of Arts and Sciences
DUNS #
City
Tucson
State
AZ
Country
United States
Zip Code
85721
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Cheng, Guilong; Cusanovich, Michael A; Wysocki, Vicki H (2006) Properties of the dark and signaling states of photoactive yellow protein probed by solution phase hydrogen/deuterium exchange and mass spectrometry. Biochemistry 45:11744-51
Van Driessche, Gonzalez; Devreese, Bart; Fitch, John C et al. (2006) GHP, a new c-type green heme protein from Halochromatium salexigens and other proteobacteria. FEBS J 273:2801-11
Meyer, T E; Bansal, A K (2005) Stabilization against hyperthermal denaturation through increased CG content can explain the discrepancy between whole genome and 16S rRNA analyses. Biochemistry 44:11458-65
Dumortier, C; Fitch, J; Van Petegem, F et al. (2004) Protein dynamics in the region of the sixth ligand methionine revealed by studies of imidazole binding to Rhodobacter capsulatus cytochrome c2 hinge mutants. Biochemistry 43:7717-24

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