NUCLEAR MAGNETIC RESONANCE--NEW METHODS AND MOLECULAR STRUCTURE DETERMINATION

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We have continued our study of biological macromolecules dissolved in a very dilute, nematic liquid crystalline (LC)phase. Various improvements to the original phospho lipid based medium have been made which extend the original 5.5-7.5 pH range to 2-11, and the temperature range which originally was 30-40Chas been increased to 20-50C, which makes the technology applicable to the majority of systems of interest. We have shown that measurement of dipolar couplings in the LC phase provides extremely precise structural information, which allows characterization of the relative, libration-averaged effective internuclear distances and angles. We have shown that measurement of dipolar couplings can provide a rapid means for evaluating the agreement between the prevalent solution structure and a structural model, and have also developed methods for improving the accuracy of structures calculated from NMR data. Most of this work has focused on a small model protein, ubiquitin, which has been well characterized by crystallographic and previous NMR studies. The methodology is also being tested on a variety of other systems, including a DNA dodecamer, the V-alpha domain of the human T-cell receptor, and DinI, a protein involved in shutting down the SOS response. - NMR, protein structure, liquid crystal, micelle, bicelle, magnetic alignment