THE USE OF OSMOLYTES TO FACILITATE PROTEIN NMR-SPECTROSCOPY

A method of stabilizing folded proteins is described, which allows NMR studies under conditions where a protein would normally be unfolded. This enables stable proteins to be examined at elevated temperatures, or spectra recorded on samples that are insufficiently stable under no rmal conditions. Up to two molar perdeuterated glycine, a potent osmol yte, can be added to aqueous protein NMR samples without altering the folded three-dimensional structure or function of the protein. However , the stability of the folded form is dramatically increased. This is illustrated for the protein lysozyme at high temperature (348 K) where the structural integrity is destroyed in standard aqueous solution, b ut is retained in the osmolyte solution. We hope that the technique wi ll be of value to those studying by NMR the structural biology of prot ein fragments and mutants, which are often of reduced stability compar ed with the original proteins.