Structure determination of membrane proteins by solution nuclear magnetic resonance spectroscopy require that they can be incorporated into detergent micelles in order to ensure that they are maintained in a folded, water-soluble state. However, detergent molecules produce micelle-protein complexes that pose unique challenges for solution NMR studies. To improve the spectroscopic properties of these complexes, it is possible to use specific isotope labeling strategies developed for the study of large water-soluble proteins by solution NMR. Specifically, the use of a highly deuterated sample that retains protons only in the Val, Leu and Ile (delta1) methyl groups has the potential to be used to determine structures of polytopic helical membrane proteins. However, while the quality of structure that can be obtained from this approach has been examined for water-soluble proteins, its utility for this class of membrane proteins has not been systematically investigated. This thesis evaluates the utility of this method for structure determination of membrane proteins by exploring structure calculation strategies from simulated NMR data sets from membrane proteins of known structure. Here I present results for a set of membrane proteins that consist of pairs or bundles of hydrophobic alpha-helices. I analyzed the impact of intra- and inter-helical NOEs on structure quality for samples specifically labeled with protons only at the methyl and amide positions In addition, I also explored the role of dihedral angles and residual dipolar couplings in an effort to find general trends to improve the accuracy of structures for polytopic a-helical membrane proteins. Based on the results of these calculations it appears that obtaining a uniform distribution of inter-helical NOES and accurately identifying transmembrane helices for dihedral angle restraints are the most important factors determining the accuracy of these simulated membrane protein structures. These results should help to guide future structure determinations for polytopic alpha-helical membrane proteins of unknown structure.
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/27556 |
| Date | January 2007 |
| Creators | Shih, Steve Chao-Chung |
| Publisher | University of Ottawa (Canada) |
| Source Sets | Université d’Ottawa |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 100 p. |
Page generated in 0.0022 seconds