Structure-Function Studies of Antifreeze Proteins

描述（由申请人提供）：世界大部分地区的环境温度接近或低于水的冰点。冰冻对大多数高等生物是致命的，并对生活在极地和亚极地环境中的鱼类、植物和昆虫等生物的生存构成严重威胁。作为回应，许多生物体已经发展出保护它们免受冷冻或其负面影响的机制。这些机制之一是产生抗冻蛋白，其特定功能是抑制冰点和修改或抑制冰晶生长。已经鉴定出几种结构非常不同的抗冻蛋白。尽管它们的序列和结构多样性，但它们都通过直接的晶体吸附和动力学生长抑制来发挥相似的功能。类似的蛋白质晶体相互作用在自然界的生物矿化过程中广泛存在。 我们的项目旨在表征这些独特蛋白质的性质，确定关键的结构和动力学特性，并研究蛋白质与水和冰的相互作用。对AFP作用机制的期望理解将促进具有限定性质的防冻剂化合物的工程化，以有效地用于细胞、血液和器官的低温储存，并赋予作物和食物抗冻性。该提案的目的集中在两种具有代表性的鱼类抗冻蛋白。具体地说， 1)III型AFP的动力学性质将通过在环境温度和生理温度下的NMR光谱弛豫实验来表征。2）三种I型AFP同种型的冰结合表面将被定位并在系统的结构-功能研究中表征。3）AFP-水相互作用将通过NMR光谱来表征，并且将开发方法来研究过冷溶液中的蛋白质和与冰结合时的蛋白质。

DESCRIPTION (provided by applicant): Ambient temperatures in wide regions of the world are close to or below the freezing point of water. Freezing is lethal to most higher organisms, and poses a severe threat to the survival of organisms such a fish, plants and insects inhabiting polar and subpolar environments. In response, many organisms have developed mechanisms that protect them from freezing or its negative consequences. One of these mechanisms is the production of antifreeze proteins, whose specific function is the suppression of the freezing point and the modification or inhibition of ice-crystal growth. Several structurally very diverse antifreeze proteins have been identified. Despite their sequence and structural diversity they all function similarly through a direct crystal adsorption and kinetic growth inhibition. Analogous protein crystal interactions are widespread through nature in bio-mineralization processes. Our project aims are to characterize the nature of these unique proteins, to identify critical structural and dynamic properties, and to study the protein interactions with water and ice. The desired understanding of the AFP mechanism of action will facilitate the engineering of antifreeze compounds with defined properties for the efficient use in cryogenic storage of cells, blood and organs, and for conferring freezing resistance to crop and food. The aims of this proposal focus on two representative types of fish antifreeze proteins. Specifically, 1) the dynamic properties of Type III AFP will be characterized by NMR spectroscopy relaxation experiments at ambient and physiological temperatures.2) the ice-binding surfaces of three Type I AFP isoforms will be localized and characterized in systematic structure-function studies.3) the AFP-water interactions will be characterized by NMR spectroscopy, and methods will be developed to study the protein in supercooled solution and upon binding to ice.