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Spectroscopic Studies of Bacterial Iron-Sulfur Proteins (Electron Paramagnetic Resonance, Magnetic Circular Dichroism)

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Spectroscopic Studies of Bacterial Iron-Sulfur Proteins (Electron Paramagnetic Resonance, Magnetic Circular Dichroism) Louisiana State University LSU Digital Commons LSU Historical Dissertations and Theses Graduate School 1986 Spectroscopic Studies of Bacterial Iron-Sulfur Proteins (Electron Paramagnetic Resonance, Magnetic Circular Dichroism). Deborah Ellen Bennett Louisiana State University and Agricultural & Mechanical College Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_disstheses Recommended Citation Bennett, Deborah Ellen, "Spectroscopic Studies of Bacterial Iron-Sulfur Proteins (Electron Paramagnetic Resonance, Magnetic Circular Dichroism)." (1986). LSU Historical Dissertations and Theses. 4173. https://digitalcommons.lsu.edu/gradschool_disstheses/4173 This Dissertation is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Historical Dissertations and Theses by an authorized administrator of LSU Digital Commons. For more information, please contact [email protected]. INFORMATION TO U SERS This reproduction was made from a copy of a manuscript sent to us for publication and microfilming. While the most advanced technology has been used to pho­ tograph and reproduce this manuscript, the quality of the reproduction is heavily dependent upon the quality of the material submitted. Pages in any manuscript may have indistinct print. In all cases the best available copy has been filmed. The following explanation of techniques is provided to help clarify notations which may appear on this reproduction. 1. Manuscripts may not always be complete. When it is not possible to obtain missing pages, a note appears to indicate this. 2. When copyrighted materials are removed from the manuscript, a note ap­ pears to indicate this. 3. 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Zeeb Road, Ann Arbor, Michigan 48106 V I 8625324 Bennett, Deborah Ellen SPECTROSCOPIC STUDIES OF BACTERIAL IRON-SULFUR PROTEINS The Louisiana State University and Agricultural and Mechanical Col.Ph.D. 1986 University Microfilms International300 N. Zeeb Road, Ann Arbor, Ml 48106 PLEASE NOTE: In all cases this material has been filmed in the best possible way from the available copy. Problems encountered with this document have been identified here with a check mark V . 1. Glossy photographs or pages _____ 2. Colored illustrations, paper or print ______ 3. Photographs with dark background ____ 4. Illustrations are poor copy ______ 5. Pages with black marks, not original copy _____ 6. Print shows through as there is text on both sides of page ______ 7. Indistinct, broken or smallprint on several pages \J 8. Print exceeds margin requirements _____ 9. Tightly bound copy with print lost in spine ______ 10. Computer printout pages with indistinct print ______ 11. Page(s) __________ lacking when material received, and not available from school or author. 12. Page(s) __________ seem to be missing in num bering only as text follows. 13. Two pages numbered . Text follows. 14. Curling and wrinkled pages _____ 15. Dissertation contains pages with print at a slant, filmed as received ________ 16. Other__________________________________________________________________ University Microfilms International SPECTROSCOPIC STUDIES OF BACTERIAL IRON-SULFUR PROTEINS A Dissertation Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Chemistry by Deborah E. Bennett B.S., Duke University, 1980 August 1986 ACKNOWLEDGEMENTS I wish to express my sincere gratitude to Dr. Michael Johnson for his patient instruction and invaluable guidance. To Dr. Brian Hales for many helpful discussions, and for the generous use of his equipment. To Joyce Morningstar, Isabel Zambrano, Barbara Dixon, Yvonne Onate, Andrzej Kowal, and Melinda Oliver for making the work enjoyable. To Robert Zinn for his assistance with the computer applications. To the staff of the office, electronics, machine, and glass shops without whom research would not be possible. To Dr. James Fee, Dr. William Sweeney, and Dr. Michael Adams and Dr. Leonard Mortenson for kindly supplying the Tt Fd, Av Fd I, and the EL. coli nitrate reductase, respectively. To my parents for believing in me. And to Gene and Jennifer for standing by me. This work was supported by the National Institute of Health, the Louisiana State University Center for Energy Studies, and the Petroleum Research Fund. ii Table of Contents Acknowledgements........................... ii Abstract................................... iv I. Introduction.................................... 1 1.1 General Introduction.................... 1 1.2 Besearch Ojectives...................... 8 1.3 Beferences............................. 11 1.4 Figures................................ 13 II. Theory..........................................17 2.1 MCD.................................... 17 2.2 EPB.................................... 34 2.3 Beferences............................. 48 2.4 Figures................. •....... -......50 III.Materials and Methods........................... 57 3.1 Instrumentation.........................57 3.1.1 MCD............................. 57 3.1.2 EPB............................. 64 3.1.3 DV-visible and CD spectroscopy 65 3.2 Sample Preparation and Handling......... 65 3.2.1 pasteurianum.................. 68 3.2.2 Is. thermophilus Fd............75 3.2.3 As. vinelandii Fd 1............... 76 3.2.4 Is. coli nitrate reductase........ 78 3.3 Beferences............................. 79 3.4 Figures................................ 80 IV. Clostridial proteins............................ 83 4.1 fit pasteur ianum Bd...................... 83 4.1.1 Introduction..................... 83 4.1.2 Besults......................... 91 4.1.3 Discussion............... ....... 96 4.2 Ct pasteurianum Fd...................... 100 4.2.1 Introduction..................... 100 4.2.2 Besults..........................105 4.2.3 Discussion....................... Ill 4.3 Beferences............................. 117 4.4 Figures..................... s.......... 121 V. The Seven Iron Ferredoxins....................... 138 5.1 Introduction........................... 138 5.2 Besults................................ 145 5.3 Discussion............................. 161 5.4 Beferences............................. 169 5.5 Figures................................ 173 VI. |i coli nitrate reductase....................... 192 6.1 Introduction........................... 192 6.2 Besults................................ 199 6.3 Discussion............................. 212 6.4 Beferences............................. 217 6.5 Figures................................ 220 VII. Appendix A ..................................... 234 Appendix B ..................................... 244 Vita.......................................... 249 iii Abstract Iron-sulfur proteins play a vital role in metabolism; mediating such life-sustaining processes as aerobic and anaerobic respiration, nitrogen fixation, and photosynthesis. This work employs low temperature magnetic circular diohroism (MCD), electron paramagnetic resonance (EPR), and UV-visible spectroscopy to characterize the iron-sulfur clusters of the following bacterial proteins: Azotobaoter vinelandii ferredoxinl, Thermus therroophilus ferredoxin, EBSh.PEi.ghift gali nitrate reductase and the rubredoxin and ferredoxin from Clostridium Eftg.fegur.iflQUm- Novel [3Fe-xS] clusters were identified in A. vinelandii Fdl, 2L thermophilus Fd, ferricyanide treated C. pasteurianum Fd, and EL. coli nitrate reductase. The uniformity of the magnetic and electronic properties of these clusters in both the oxidized and the reduced states indicates a common iron-sulfur core'structure for this type of cluster. EL coli nitrate reductase is the first example of an active enzyme which contains a [3Fe-xS] cluster. This argues against the currently prevailing hypothesis that all such clusters are isolation artifacts. This work has also developed the potential of low i v temperature MCD for the detection and characterization of iron-sulfur clusters in multicluster enzymes. Studies on the well-characterized Clostridial proteins demonstrated that MCD magnetization curves provide a selective method of obtaining ground state g-values, spin states, and estimations of the polarizations of the electronic transitions for randomly oriented samples. Moreover, zero field splitting parameters were obtained by a detailed study of the temperature dependence of individual MCD transitions. This has led to a more detailed understanding of the oomplex Kramer's and non-Kramer's ground states exhibitied by reduced [3Fe-xS] clusters (S=2) and oxidized and reduced rubredoxin
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