Spin Labeled Ice Binding Proteins for Molecular Antifreeze Mechanistic Study

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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.