STRUCTURAL STUDIES ON ANTIFREEZE PROTEINS

零度以下的温度严重威胁到 生活在极地和亚极地环境中的有机体。许多生物体， 包括植物、昆虫和鱼类在内的物种已经适应和发展 降低冰冻风险的保护机制。某些鱼 产生抗冻蛋白，即降低冰冻程度的物质 通过与其结合并抑制其生长来抑制其体液的点数 结成冰晶。类似的化合物(热滞蛋白)是 目前正从植物和昆虫中分离出来。另外，蛋白质- 晶体相互作用在生物学上是常见的，在过程中也很重要 例如生物矿化和钙化。这项研究项目 计划研究几种结构与功能的关系 抗冻蛋白，表征其独特的活性并鉴定 活动所需的结构特征或共同主题。长的- 学期目标是提高我们对动力学和 蛋白质吸附到冰上的热力学方面 确定观察到的高结合亲和力的来源，并 降低凝固点的机理。这些研究将增加我们的 对蛋白质表面和蛋白质晶体的基本认识 相互作用，并旨在促进防冻剂的工程 用于细胞、血液和器官的低温储存的化合物， 还用于提高作物和食物的抗冻性。我的实验室 致力于从结构和机制上描述 不同类别的抗冻蛋白的数量。具体目标 该项目的这一阶段将利用同核和 异核多维核磁共振波谱与核磁共振 定点突变、计算方法和结晶 实验：I)确定类型的三维结构 2)鲱鱼抗冻蛋白，II)测定溶液结构 从海鸦中提取2型抗冻蛋白，III)测定 黄粉虫热滞蛋白的结构研究 以及iv)研究蛋白质-水和蛋白质-冰 这些蛋白质的相互作用。

Subfreezing temperatures pose a severe threat to the survival of organisms inhabiting polar and subpolar environments. Many organisms, including plants, insects and fish, have adapted and developed protective mechanisms which lower the risk of freezing. Certain fish produce antifreeze proteins, i.e. substances which lower the freezing points of their body fluids by binding to and inhibiting the growth of seed ice crystals. Similar compounds (thermal hysteresis proteins) are currently being isolated from plants and insects. Also, protein- crystal interactions are biologically common and important in processes such as biomineralization and calcification. This research project plans to investigate the structure-function relationship of several antifreeze proteins, characterize their unique activity and identify structural features or common motifs required for activity. The long- term objectives are to improve our understanding of the kinetic and thermodynamic aspects of the protein adsorption to ice in order to identify the source for the observed high binding affinity and mechanism of freezing point depression. The studies will increase our basic understanding on protein-surface and protein-crystal interactions, and are aimed to facilitate the engineering of antifreeze compounds for use in the cryogenic storage of cells, blood and organs, and for conferring freezing resistance to crop and food. My laboratory is dedicated to the structural and mechanistic characterization of a number of distinct classes of antifreeze proteins. The specific aims of this stage of the project will be to utilize homonuclear and heteronuclear multi-dimensional NMR-spectroscopy in combination with site-specific mutagenesis, computational methods and crystallization experiments to: i) determine the three dimensional structure of Type 2 antifreeze protein from herring, ii) determine the solution structure of Type 2 antifreeze protein from sea raven, iii) to determine the structure of a thermal hysteresis protein from the beetle Tenebrio molitor, and iv) to investigate the protein-water and protein-ice interactions of these proteins.