Spin Labeled Ice Binding Proteins for Molecular Antifreeze Mechanistic Study

描述(申请人提供)：冰结合蛋白(IBPs)，也称为抗冻蛋白(AFP)，存在于某些生物中，包括鱼、昆虫和植物，以保护活细胞在零下环境中免受冰冻损害。因此，IBPs有望应用于生物医学领域，例如延长血液、哺乳动物细胞、组织和器官在低温下的保质期。矛盾的是，在冷冻手术中，发现高浓度的IBPs在摧毁恶性肿瘤方面有增强作用。IBPs的作用机制归因于它们与特定冰面结合的能力，从而抑制种子冰晶的生长。通过同样的机制，IBPs还可以抑制冰的重结晶，这可能会产生大的、对组织具有破坏性的冰晶。有趣的是，高浓度的IB还会产生针状冰晶，损害细胞。IBPS的作用机制与水中电解质降低凝固点的综合效应有根本的不同。电解液降低冰点的缺点源于改变活细胞的渗透膜的后果。由于抑制冰生长的机制要有效得多，所以IBPS对渗透膜几乎没有影响。尽管人们对IBPs的结构和功能进行了广泛的研究，但其在分子水平上的基本作用机制尚不清楚。水/IBP/冰的复杂体系是阻碍分子机理研究的主要障碍。这种复杂性已经排除了许多常规的光谱和衍射法的使用。包括核磁共振和电子顺磁共振在内的磁共振技术为表征液态和固态体系中从分子尺度到微尺度的局部结构提供了多种检测方法。此外，磁共振技术也是探测分子动力学和相互作用信息的有力工具。在这项研究中，我们将发展和应用高灵敏度的磁共振方法来研究IBPS在水-IBP-冰界面区与冰/水相互作用的几个结构和动力学方面的问题。这项研究的结果将为理解IBPs的作用机制提供分子知识，进而为后续开发生物医学应用的新型防冻材料和方法奠定基础。该项目还将对南加州大学本科生和研究生的职业发展产生重大影响。

DESCRIPTION (provided by applicant): Ice binding proteins (IBPs), also known as antifreeze proteins (AFPs), are found in certain organisms including fish, insects and plants, to protect the living cells from freezing damage in subzero environments. Therefore, IBPs are promising to be used in biomedical applications, such as in prolonging the shelf lives of blood platelets, mammalian cells, tissues and organs at low storage temperatures. Paradoxically, IBPs at high concentrations were found to enhance in destroying malignant tumors during cryosurgery. The mechanism of action of IBPs is attributed to their ability to bind to specific ice surfaces, thereb inhibiting the growth of seed- ice crystals. By the same mechanism, IBPs can also inhibit the recrystallization of ice, which can generate large, tissue-damaging ice crystals. Interestingly, IB at high concentration can also create needle like ice crystals to damage cells. IBPs' mechanism of action differs fundamentally from the colligative effect of freezing point depression by electrolytes in water. The drawback of electrolytes in freezing point depression arises from the consequence in altering the osmoses of living cells. IBPs have virtually no effect on the osmoses because of the mechanism of ice growth inhibition which is far more efficient. Although the structures and function of IBPs have been extensively studied, the fundamental mechanism of action at molecular level has yet to be understood. The major barrier to the study of the molecular mechanism arises from the complicated water/IBP/ice system. This complexity has ruled out the uses of many routine spectroscopic and diffraction methods. Magnetic resonance techniques including NMR and EPR provide versatile detection methods for characterizing local structures from molecular scale to microscale in both liquid and solid state systems. In addition, magnetic resonance techniques are also powerful to probe the information of molecular dynamics and interactions. In this study, high sensitive magnetic resonance methods will be developed and applied to study several structural and dynamic aspects of IBPs in interacting with ice/water in the water-IBP-ice interfacial region. The outcome of this proposed study will provide molecular knowledge to understand the mechanism of action of IBPs which, in turn, will lay the basis for the subsequent development of novel antifreeze materials and methods for biomedical applications. This project will also have significant impact on the professional developments of undergraduates and graduate students at CSULA.