Novel small peptide polarizing agents for dynamic nuclear polarization (DNP) nuclear magnetic resonance (NMR) spectroscopy
Versatile small biradical peptide molecules that can serve as biradical polarizing agents for dynamic nuclear polarization (DNP) solid-state nuclear magnetic resonance spectroscopy.
DNP methodology offers dramatic sensitivity enhancements of NMR experiments (up to 1-2 orders of magnitude) by transferring the large electron spin polarization to the nuclei of interest, and is currently one of the research frontiers in the magnetic resonance field with numerous applications to biology, chemistry and material science. There is a need for polarizing agents that can be readily produced in large amounts and whose properties can be easily modified for specific applications, such as the study of interactions between biomolecules inside living cells.
Researchers at The Ohio State University, led by Christopher Jaroniec, have developed a series of small, biradical peptide molecules that can be synthesized using a facile and modular approach based on solid phase peptide synthesis. These molecules offer virtually unlimited opportunities for tuning their physicochemical properties, including solubility in water or organic solvents, ability to be covalently attached to large biomacromolecules or material surfaces, and ability to specifically target and bind non-covalently to certain receptor molecules (e.g. on the surface of cells). For initial demonstration purposes, the research group has synthesized a series of four biradical peptides, each containing two TOAC non-natural amino acids featuring stable nitroxide radicals. They have demonstrated that all four compounds outperform one of the gold standards in the DNP solid-state NMR field (TOTAPOL) in terms of the efficiency of the NMR signal enhancement. At the same time, the general route by which the biradical polarization agents have been prepared enables them to be easily modified for a variety of modifications in biology and materials science.