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Gennis, Robert B. Hacker, Beth Marie 2011-05-07T13:20:35Z 2011-05-07T13:20:35Z 10000-01-01 1994 The cytochrome $bc\sb1$ complex is a multisubunit integral membrane protein. This enzyme is a central component in electron transport where it oxidizes quinol while forming a transmembrane proton gradient. The cytochrome b subunit is the locus of two distinct quinol binding sites as well as the heme groups. Despite the its importance, little is known about the $bc\sb1$ complex structure. The focus of this thesis is to identify the residues that comprise the quinol reductase (Q$\sb{\rm i}$) site in the photosynthetic bacteria Rhodobacter sphaeroides. These residues were identified by using site-directed mutagenesis and spectroscopic analysis. Since no crystal structure exists for the $bc\sb1$ complex, proposed mutations were based on sequence and inhibitor resistance data from other species. Initial results proved that the Q$\sb{\rm i}$ site function could be perturbed by the mutants and that the change in electron flow can be monitored spectroscopically. Totally conserved residues along the cytoplasmic interface were found to be essential for Q$\sb{\rm i}$ site structure. The only residues found in the cytoplasm that help define the Q$\sb{\rm i}$ site are those that can form hydrogen bonds. From this information, a helical wheel model as well as a topological map of the cytochrome b subunit were created to visualize the putative Q$\sb{\rm i}$ site domain. This represents the first experimentally-based model of the Q$\sb{\rm i}$ site. Made available in DSpace on 2011-05-07T13:20:35Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9503202.pdf: 3073492 bytes, checksum: e7ed39c58053d22e9b3248de8907e292 (MD5) Previous issue date: 1994 Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T14:53:32Z Item is restricted indefinitely. Restriction data tranferred 2014-07-01T11:24:46-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: ETDs are only available to UIUC Users without author permission ETDs are only available to UIUC Users without author permission U of I Only AAI9503202 (UMI)AAI9503202 http://hdl.handle.net/2142/21836 eng Copyright 1994 Hacker, Beth Marie Biology, Molecular Chemistry, Biochemistry Mutational studies of the cytochrome bc(1) complex of Rhodobacter sphaeroides text Biochemistry Biochemistry University of Illinois at Urbana-Champaign Dissertation Ph.D.