Spin Labeled Ice Binding Proteins for Molecular Antifreeze Mechanistic Study

描述（由申请人提供）：冰结合蛋白（IBP），也称为抗冻蛋白（AFP），存在于某些生物体中，包括鱼、昆虫和植物，以保护活细胞免受零度以下环境中的冷冻损伤。因此，IBP有望用于生物医学应用，例如在低温储存条件下延长血小板、哺乳动物细胞、组织和器官的保质期。有趣的是，高浓度的IBPs在冷冻手术中被发现增强对恶性肿瘤的破坏。IBPs的作用机制是由于它们能够与特定的冰表面结合，从而抑制种子冰晶的生长。通过相同的机制，IBPs还可以抑制冰的重结晶，这可能会产生大的，组织损伤的冰晶。有趣的是，高浓度的IB也可以产生针状冰晶，从而损伤细胞。IBPs的作用机制与水中电解质凝固点降低的依数效应根本不同。电解质在凝固点降低中的缺点来自于改变活细胞的构象的结果。IBPs实际上对冰藻没有影响，因为冰藻生长抑制的机制要有效得多。虽然IBPs的结构和功能已被广泛研究，但在分子水平上的基本作用机制尚未被理解。水/IBP/冰复杂体系是研究分子机理的主要障碍。这种复杂性排除了许多常规光谱和衍射方法的使用。包括NMR和EPR在内的磁共振技术为表征液态和固态系统中从分子尺度到微观尺度的局部结构提供了通用的检测方法。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手段。在这项研究中，高灵敏度的磁共振方法将被开发和应用于研究的几个结构和动力学方面的IBP与冰/水在水-IBP-冰界面区域的相互作用。这项拟议研究的结果将提供分子知识，以了解IBPs的作用机制，反过来，这将为后续开发用于生物医学应用的新型防冻材料和方法奠定基础。该项目也将对CSULA的本科生和研究生的专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.