Denatured states of proteins and their roles in folding and stability

Far from adopting featureless random coils, denatured states of proteins frequently exhibit significant amounts of persistent residual structure. Earlier studies that characterized this structure by methods of relatively low resolution are now being extended to significantly higher resolution using NMR spectroscopy. Although no description of the structure of a protein in a denatured state has been completed, trends in much of the data published to date suggest that the amount of structure depends critically on the solution conditions and that a significant fraction is native-like. Because of the recent realization of the importance of denatured states in a number of biochemical processes and in protein folding, a growing number of proteins are being submitted to structural analysis under a variety of denaturing conditions.