Flexibility vs Thermal Stability in Rubredoxin Proteins

描述（由申请人提供）：微生物的最新表征 生活在90摄氏度以上的极端嗜热生物， 提供了一组越来越多的蛋白质， 比从生活在典型环境中的生物体中获得的同源蛋白质 温度（即嗜温菌）。有了大量的基因组序列信息 目前可用的基于酶的工业过程和药物疗法 利用生物活性蛋白质被定位为大大扩展的发展。 超嗜热蛋白的物理研究受到 期望与同源嗜温蛋白质的详细比较将 深入了解如何系统地提高热稳定性 被改造成蛋白质。不幸的是，迄今为止的物理研究 很明显，热稳定性的结构基础在细节上是微妙的。 此外，超嗜热酶被一致发现活性低得多 在相同的环境下测试时， 条件热稳定性和降低的催化活性 超嗜热蛋白通常归因于增加的构象 刚度 理解自然状态下的灵活性与 全球稳定需要确定 运动之间的不同嗜温和超嗜热蛋白质，以及 一种系统地改变这些影响的方法。来自 激烈热球菌和巴氏梭菌提供了一个很好的模型系统， 其中所有骨架酰胺的酰胺交换可以在宽的范围内监测， pH值、温度和变性剂的范围， 构象转变快于和慢于1秒（-1）。双氧 顺磁弛豫测量提供了时间平均的测量， O2在整个蛋白质结构中的空间分布。而且 两种红细胞毒素之间序列变异的空间分布 提供了一个系统的相互转换的路径， 交互.

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.