NUCLEAR MAGNETIC RESONANCE--NEW METHODS AND MOLECULAR STRUCTURE DETERMINATION

前一年开发的产生共鸣的方法 在较大蛋白质中的指配已经得到了扩展和改进。这个 大共振线对新方法的影响较小 宽度大约与分子量成正比 蛋白质。一个四维核磁共振实验已经被开发出来 极大地减少了最拥挤的 NOE光谱的区域，现在允许研究相互作用 在相当大的蛋白质中的脂肪残基之间。新的 实验提供对大量参数的访问，例如 13C和15N化学位移和耦合常数，以及比较 结晶学数据表明，这些参数包含 结构上重要的信息。新的技术已经被 应用于钙调素与α-氨基丁酸相互作用的研究 肌球蛋白轻链激酶26个残基片段。发生戏剧性的变化 钙调素的两个结构域在细胞上的相对定位 观察到与多肽的络合作用，多肽从 络合时由无规卷曲转变为α螺旋构象。一个 目前正在进行详细的结构表征。

Approaches developed in the previous year for making resonance assignments in larger proteins have been extended and improved. The new methods are affected to a lesser degree by the large resonance line widths which are approximately proportional to the molecular weight of the protein. A four-dimensional NMR experiment has been developed that dramatically reduces spectral overlap in one of the most crowded regions of the NOE spectrum, now permitting the study of interactions between aliphatic residues in proteins of a substantial size. The new experiments provide access to a large number of parameters, such as 13C and 15N chemical shifts and coupling constants, and comparison with crystallographic data indicates that these parameters contain structurally important information. The new techniques have been applied to the study of the interaction between calmodulin and a 26-residue fragment of myosin light chain kinase. A dramatic change in the relative orientation of the two domains of calmodulin upon complexation with the peptide is observed and the peptide changes from a random coil to an alpha-helical conformation upon complexation. A detailed structural characterization is currently in progress.