Electron spin labeled ice binding compounds used for carrying paramagnetic centers for dynamic nuclear polarization

Abstract

Spin-labeled ice binding compounds (IBCs) including ice binding proteins (IBPs) or antifreeze proteins (AFPs) and their analogs may carry paramagnetic centers for dynamic nuclear polarization (DNP), for enhancing nuclear magnetic resonance (NMR) signal intensities. Use of spin-labeled IBCs to perform DNP exploits the IBCs' ability to homogeneously distribute the paramagnetic centers in frozen water solution at low temperature, leading to high DNP efficiency. Other advantages of using spin-labeled IBCs include cryo-protecting biological samples; cryo-preserving relative positions and orientations of the spin labeling groups; selecting positions and orientations of spin labeling groups with freedom and without technical barriers to making multiple spin labels in an IBC; and enabling use of a solvent that is primarily water for DNP at low temperatures in view of the potentially high water solubilities of spin-labeled IBCs.