Antifreeze Mechanistic Study of Ice Binding Proteins (IBPS) through VT Epr Study on Spin Labeled IBPs

Abstract

Ice binding proteins (IBPs) bind to the surfaces of seed ice crystals to inhibit their growths and recrystallizations which prevents cell damages in IBP producing organisms. We have studied the mechanism of ice growth inhibition by VT EPR techniques on spin labeled type I IBPs at different sites along its α-helical structure. The spin labeled IBPs were achieved through method of cysteine-substitution mutagenesis and alteration of the sulfhydryl groups with nitroxide spin labels. Combination of the EPR spectra at low temperatures and observation of their inhibitions to the growths of ice crystals gives us insight into their antifreeze mechanism on both a molecular scale and microscopic scale. This poster will focus on presenting the EPR experimental results, while another poster of my research lab will focus on the observation on ice crystals inhibited by the spin labeled IBPs. Categorization of molecular motion regimes of the spin labeling groups among fast, intermediate, slow and anisotropic tumblings were determined through the VT EPR spectra which in turn reveal the water/ice surroundings along the different sites of the spin labeled IBPs at various low temperatures.