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X-band EPR Spectroscopy of Spin-labeled Membrane Biomolecules Incorporated into Magnetically Aligned Phospholipid Bilayers

Cardon, Thomas B
http://rave.ohiolink.edu/etdc/view?acc_num=miami1154747640

Abstract Details

2006, Doctor of Philosophy, Miami University, Chemistry and Biochemistry.
The orientation, structure and dynamics of spin-labeled integral membrane peptides/proteins can be obtained directly from the orientation-dependent hyperfine splittings of the spin-labeled EPR spectra. Various spin-labeled biomolecules were incorporated into magnetically alignable phospholipid bilayers called bicelles. Bicelles are a binary mixture of long-chain and short-chain phospholipids. Dimyristoyl phosphatidylcholine (DMPC) and dihexanoyl phosphatidylcholine (DHPC) were used as the long-chain and short-chain phospholipids, respectively. The mole ratio of DMPC/DHPC is referred to as the q-ratio. The normal to the phospholipid bilayers, n, magnetic field, Bo, when the bicelles are doped with either Tm3+ or Dy3+ cations, respectively (Chapters 1 and 2). The affects on the relaxation rates of the spin label and the magnetic alignment behavior of bicelles caused by doping the bicelles with strong paramagnetic lanthanide cations were investigated in Chapters 1 and 3. Chapters 4 and 5 illustrate how varying the experimental conditions and sample composition affect the magneitc alignment behavior of the bicelles and the molecular ordering, Smol, of the spin label. Smol and the temperature range over which the magnetic alignment was stable increased as the q-ratio increased. The magnetic alignment of samples having a q-ratio of 9.5 was stable at temperatures between 298 K (gel phase) to 318 K (liquid crystalline phase), whereas the magnetic alignment of samples having a q-ratio of 2.5 was stable at temperatures between 308 K and 318 K. For the first time, highly orientation-dependent hyperfine splittings were observed for a spin-labeled peptide (TOAC18 AChR M2), corresponding to the pore-lining transmembrane domain of the nicotinic acetylcholine receptor, reconstituted into magnetically aligned bicelles (Chapter 6). The EPR spectra of TOAC18 AChR M2 was found to be transmembrane with a helical tilt of 10 degrees and the principal z-axis of the TOAC spin label made a 18.9 degree angle with the helical axis, which agrees very well with results from solid-state NMR spectroscopic and X-ray crystallographic studies. Thus, spin-labeled EPR spectroscopy could be a powerful structural biology tool that is more efficient and less expensive than solid-state NMR spectroscopy.
Gary Lorigan (Advisor)
150 p.
Chemistry, General
bicelles; EPR; DMPC; PHOSPHOLIPID BILAYERS; bicelle disks

Recommended Citations

Citations

  • Cardon, T. B. (2006). X-band EPR Spectroscopy of Spin-labeled Membrane Biomolecules Incorporated into Magnetically Aligned Phospholipid Bilayers [Doctoral dissertation, Miami University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=miami1154747640

    APA Style (7th edition)

  • Cardon, Thomas. X-band EPR Spectroscopy of Spin-labeled Membrane Biomolecules Incorporated into Magnetically Aligned Phospholipid Bilayers. 2006. Miami University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=miami1154747640.

    MLA Style (8th edition)

  • Cardon, Thomas. "X-band EPR Spectroscopy of Spin-labeled Membrane Biomolecules Incorporated into Magnetically Aligned Phospholipid Bilayers." Doctoral dissertation, Miami University, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=miami1154747640

    Chicago Manual of Style (17th edition)

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© 2006, all rights reserved.
This open access ETD is published by Miami University and OhioLINK.