RELATIONSHIP BETWEEN ENZYME STABILITY & ENZYME FUNCTION

我们提出了一个合作项目之间的德州农工大学和恩格尔哈特分子生物学研究所，俄罗斯科学院，在莫斯科在该地区的构象稳定性的酶。 具体来说，我们计划测试的假设，蛋白质残基催化不是最佳的蛋白质稳定性，使用微生物核糖核酸酶作为模型。 我们将使用来自中间芽孢杆菌的RNA酶、binase和金色链霉菌的RNA酶Sa来研究消除或减少酶的催化活性的活性位点残基的变化对酶的热稳定性的影响。 此外，我们将通过评估与蛋白质抑制剂芽孢杆菌RNA酶抑制剂及其突变体复合物中蛋白质的熔化来估计限制RNA酶活性sties中特定残基的流动性的稳定作用。 调查的主要目标是确定存在于RNases的蛋白质的热稳定性和催化效率所需的活性位点残基的构象灵活性之间的相互关系。 莫斯科研究组最近观察到，对于由芽孢杆菌RNA酶和双酶分子的不同部分组成的嵌合RNA酶，酶活性对热稳定性的反向依赖性。 该项目的意义在于，我们将学会预测活性位点残基的取代如何影响酶的功能、折叠和稳定性。 这可能具有重新设计酶以产生所需催化性质和稳定性的未来潜力。

We propose a collaborative project between Texas A and M University and the Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, in Moscow in the area of the conformational stability of enzymes. Specifically, we plan to test the hypothesis that protein residues contributing to catalysis are not optimal for protein stability, using microbial ribonucleases as models. We will study the effect of changes in the active site residues that abolish or diminish the enzyme's catalytic activity on the enzyme's thermostability using the RNases from Bacillus intermedius, binase, and Streptomyces aureofaciens, RNase Sa. In addition, we will estimate the stabilizing effect of restricting the mobility of particular residues in the RNase active sties by assessing the melting of proteins in complexes with the protein inhibitor barstar and its mutants. The primary goal of the investigation is to ascertain the existence in RNases of an interrelation between the thermostability of the protein and the conformational flexibility of active site residues required for catalytic efficiency. The Moscow group has recently observed an inverse dependence of enzymatic activity on thermal stability for chimeric RNases composed of different parts of barnase and binase molecules. The significance of the proposed project is that we will learn to predict how substitutions at active site residues will affect the function, folding, and stability of an enzyme. This can have future potential for redesign of enzymes to generate the desired catalytic properties and stability.