Structure-Function Studies of Antifreeze Proteins

描述（由申请人提供）：世界上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，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，许多生物已经发展出保护它们免受冷冻或其负面影响的机制。其中一种机制是产生抗冻蛋白，其具体功能是抑制冰点和修饰或抑制冰晶生长。已经确定了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，但它们都通过直接晶体吸附和动力学生长抑制而起类似的作用。类似的蛋白质晶体相互作用在生物矿化过程中广泛存在。

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.