Flexibility vs Thermal Stability in Rubredoxin Proteins

描述(由申请人提供)：生物体的最新特征 生活在90摄氏度以上的动物，也就是所谓的嗜热者 提供了一组不断增加的蛋白质，这些蛋白质的热稳定性要好得多 从生活在典型环境中的生物体中获得的同源蛋白 温度(即中温菌)。拥有海量的基因组序列信息 目前已有基于酶的工业工艺和药物疗法 利用生物活性蛋白质为极大地扩展开发做好了准备。 超嗜热性蛋白质的物理研究是由 期望与同源的中亲蛋白质进行详细的比较 深入了解如何系统性地提高热稳定性 被改造成蛋白质。不幸的是，迄今为止的物理研究已经取得了 显然，热稳定的结构基础在细节上是微妙的。 此外，人们一致发现，超嗜热酶的活性要低得多。 当在相同的环境下测试时，它们的中温对应物比 条件。其热稳定性和降低的催化活性 超嗜热性蛋白质通常被归因于构象增加 僵硬。 理解原生状态中的灵活性和 全球稳定需要确定时间框架和规模 中温和超嗜热蛋白质之间的不同运动以及 一种系统地改变这些影响的方法。来自印度的红豆素 狂热杆菌和巴氏梭菌提供了一个很好的模型系统 所有主链酰胺的酰胺交换可以在广泛的范围内监测 酸碱度、温度和变性剂的范围 构象转变的速度和速度都快于1秒(-1)。氧气 顺磁松弛测量提供了一种时间平均的测量 氧在整个蛋白质结构中的空间分布。此外， 两种Rubredoxin之间序列变异的空间分布 提供了一种系统的相互转换路径，保留了本机风格 互动。

DESCRIPTION (provided by applicant): The recent characterizations of organisms that live at temperatures above 90oC, so-called hyperthermophiles, have provided an ever-increasing set of proteins which are far more thermostable than the homologous proteins obtained from organisms living at typical ambient temperatures (i.e. mesophiles). With the massive genomic sequence information now available, enzyme-based industrial processes and pharmacological therapies utilizing bioactive proteins are positioned for greatly expanded development. Physical studies of the hyperthermophile proteins are stimulated by the expectation that detailed comparison to the homologous mesophile proteins will provide insight into how increased thermal stability can be systematically engineered into proteins. Unfortunately, the physical studies to date have made it clear that the structural bases of thermostabilization are subtle in detail. Furthermore, hyperthermophile enzymes are uniformly found to be far less active than their mesophile counterparts when tested under the same ambient conditions. Both thermal stability and reduced catalytic activities of hyperthermophile proteins are commonly ascribed in increased conformational rigidity. Understanding the relationship between flexibility in the native state and global stability requires determination of the timeframe and magnitude of motions which differ between mesophile and hyperthermophile protein as well as an approach to systematic alteration of these effects. The rubredoxins from Pyrococcus furiosus and Clostridium pasteurianum offer a good model system in which the amide exchange for all backbone amides can be monitored over a wide range of pH, temperature and denaturant in a fashion which distinguishes conformational transitions both faster and slower than 1 sec(-1). Dioxygen paramagnetic relaxation measurements provide a time averaged measure of the spatial distribution of O2 throughout the protein structure. Furthermore, the spatial distribution of the sequence variations between the two rubredoxins provides a systematic path of interconversion which preserves native-like interactions.