Impact of naturally occurring osmolytes on protein structure and energetics

描述(由申请人提供)：保护渗透压是肾髓质处理高达1.5米的细胞内尿素浓度的非凡能力的原因。这些小有机分子普遍存在于许多组织的细胞中，它们在肾脏中作用的一个重要部分是稳定细胞内蛋白质，使其免受尿素的有害影响。除了对我们的生存至关重要之外，渗透激素水平的失衡在多囊肾病、糖尿病和脑水肿等疾病中也起着关键作用。虽然渗透分子的许多生物学作用是由它们对蛋白质的溶剂化作用产生的，但蛋白质溶剂化是如何促进这些作用的尚不清楚。这种知识上的差距阻碍了对渗透调节效应及其在正常和疾病状态下的作用的全面了解。我们的长期目标是了解渗透分子、水和生物分子之间的相互作用如何一方面引起渗透应激反应，另一方面引起疾病。通过测量蛋白质侧链和肽主链基团(GTFEs)从水到渗透分子溶液的转移自由能，我们最近在如何预测渗透分子中蛋白质稳定性的能量学方面取得了令人瞩目的发现。我们的目标是巩固和使用这一能力来确定负责蛋白质稳定性的潜在作用力，并预测渗透分子对变性系综结构收缩和增加的能量效应。我们将扩大GTFE的使用范围，以预测蛋白质-蛋白质相互作用自由能，更好地了解渗透分子浓度波动如何影响对细胞反应至关重要的关键蛋白质-蛋白质相互作用，并确定肾脏渗透分子在影响蛋白质性质方面协同、负面或独立作用的程度。我们的目标是将我们预测蛋白质稳定性和溶剂化效应的能量学的能力与Kirkwood-Buff方法相结合，后者在结构上将水*渗透分子*蛋白质相互作用与能量学联系起来，从而对蛋白质溶剂化提供比目前存在的更详细的机制理解。相关性：该项目将有助于更好地了解渗透膜如何保护蛋白质在恶劣条件下不被展开，以及渗透膜水平的不平衡如何导致多囊肾病、糖尿病和脑肿胀等疾病的病理。我们的工作将在制药业的疫苗和蛋白质/多肽药物的稳定方面有实际应用。

DESCRIPTION (provided by applicant): Protecting osmolytes are responsible for the kidney medulla's extraordinary ability to cope with intracellular urea concentration as high as 1.5M. These small organic molecules are common in cells of many tissues, and an important part of their action in kidney is to stabilize intracellular proteins against the deleterious effects of urea. Besides being essential for our survival, imbalances in osmolyte levels play key roles in such conditions as polycystic kidney disease, diabetes mellitus, and brain edema. Though many biological roles of osmolytes arise from their solvation of proteins, it is unknown how protein solvation facilitates these roles. This gap in knowledge prevents a complete understanding of osmolyte effects and their roles in normal and disease states. Our long-term goal is to understand how interactions among osmolytes, water, and biomolecules give rise to osmotic stress response on the one hand, and disease on the other. Using measurements of the transfer free energy of protein side-chain and peptide backbone groups (GTFEs) from water to osmolyte solution, we recently made the remarkable discovery of how to predict the energetics of protein-stability in osmolytes. Our aims are to consolidate and use this ability to determine the underlying forces responsible for protein stability, and to the predict energetic effects of osmolytes on contraction and accretion of structure in denatured ensembles. We will extend our use of GTFEs to enable predictions of protein-protein interaction free energies, to better understand how fluctuating osmolyte concentrations affect key protein-protein interactions vital to cellular responses, and determine the extent to which kidney osmolytes act synergistically, negatively, or independently in affecting the properties of proteins. We aim to merge our ability to predict the energetics of protein stability and solvation effects with Kirkwood-Buff approaches that structurally relate water*osmolyte*protein interaction with the energetics, to give a considerably more detailed mechanistic understanding of protein solvation than currently exists. Relevance: This project will lead to a better understanding of how osmolytes protect proteins from unfolding under harsh condition, and how imbalances in osmolyte levels can contribute to the pathology of such conditions as polycystic kidney disease, diabetes mellitus, and brain swelling. Our work will have practical applications in the pharmaceutical industry for stabilization of vaccines and protein/ peptide drugs.