NUCLEAR MAGNETIC RESONANCE--NEW METHODS AND MOLECULAR STRUCTURE DETERMINATION

我们继续我们的研究，生物大分子溶解在一个非常稀，液晶（LC）相。 化学位移各向异性（CSA）的质子，碳和氮骨架原子的蛋白质泛素，溶解在LC介质中的研究，揭示了CSA和蛋白质二级结构之间的明显相关性。 已经开发了一种方法，定量预测已知形状的大分子的取向的情况下，其中的LC颗粒是近中性的。这一信息证实了溶液中抗HIV蛋白cyanovirin-N的单体形式。 已经开发出允许在缓慢翻滚的大分子中测量偶极耦合的方法。 我们已经表明，在有利的情况下，它是可以定义的蛋白质骨架的三维结构的基础上，它的偶极耦合，只要测量可以在两个不同的LC介质中进行。这一发展有可能显着减少蛋白质结构测定所需的时间。 偶极耦合被用于确定的RecA结合蛋白DinI的结构，并获得高分辨率的DNA十二聚体d（CGCGAATTCGCG）2的结构。

We have continued our study of biological macromolecules dissolved in a very dilute, nematic liquid crystalline (LC) phase. Study of chemical shift aniostropy (CSA) of proton, carbon and nitrogen backbone atoms in the protein ubiquitin, dissolved in a LC medium, revealed distinct correlations between CSA and protein secondary structure. A method has been developed that quantitatively predicts alignment of macromolecules of known shape for the case where the LC particles are nearly neutral. This information confirmed the monomeric form of the anti-HIV protein cyanovirin-N in solution. Methods have been developed that permit measurement of dipolar couplings in slowly tumbling macromolecules. We have shown that in favorable cases it is possible to define the three-dimensional structure of a protein backbone solely on the basis of its dipolar couplings, provided that measurements can be performed in two different LC media. This development holds potential to significantly decrease the time required for protein structure determination. Dipolar couplings were used for determination of the structure of the RecA binding protein DinI, and for obtaining a high-resolution structure of the DNA dodecamer d(CGCGAATTCGCG)2.