The conformations and dynamics of four tryptophan side-chains in the membrane polypeptide gramicidin A have been investigated by solid state nuclear magnetic resonance. It has been found, through the analyses of the $\sp{15}$N NMR data of fast frozen unoriented and oriented samples in lipid bilayers at various temperatures, that side-chain motions of tryptophans are dominated by the librational motion about the C$\sb\beta$-C$\sb\gamma$ bond. The librational amplitudes have been determined for four tryptophans, and the time scale of such librational motion has been obtained. Motionally averaged side-chain conformations have been achieved from orientational constraints using $\sp2$H and $\sp{15}$N NMR spectra of oriented samples of d$\sb5$-TrpxgA and $\sp{15}$N$\sb{\varepsilon1}$-Trp$\rm\sb x$gA (x = 9, 11, 13, 15). Based on the dynamic and conformational characterization, the interaction between tryptophans and lipid, the effects of tryptophans on gramicidin A secondary structure, and the relationship between the indole dipole moments and the channel conductance have been discussed. Through this study, it is demonstrated that a high resolution characterization of dynamics and structure for important sites in membrane bound proteins and polypeptides can be uniquely achieved by solid state NMR. Such characterizations require method development to separate the entwined effects of structure and dynamics on the nuclear spin interactions. The combined synergetic effect of structure and dynamics yields detailed functional understanding. / Source: Dissertation Abstracts International, Volume: 56-01, Section: B, page: 0218. / Major Professor: Timothy A. Cross. / Thesis (Ph.D.)--The Florida State University, 1994.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_77343 |
| Contributors | Hu, Weidong., Florida State University |
| Source Sets | Florida State University |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | 245 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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