Using ¹ H^N amide temperature coefficients to define intrinsically disordered regions: An alternative NMR method

This report describes a cost-effective experimental method for determining an intrinsically disordered protein (IDP) region in a given protein sample. In this area, the most popular (and conventional) means is using the amide (¹ H^N ) NMR signal chemical shift distributed in the range of 7.5-8.5 ppm. For this study, we applied an additional step: analysis of ¹ H^N chemical shift temperature coefficients (¹ H^N -CSTCs) of the signals. We measured ¹ H-¹⁵ N two-dimensional NMR spectra of model IDP samples and ordered samples at four temperatures (288, 293, 298, and 303 K). We derived the ¹ H^N -CSTC threshold deviation, which gives the best correlation of ordered and disordered regions among the proteins examined (below -3.6 ppb/K). By combining these criteria with the newly optimized chemical shift range (7.8-8.5 ppm), the ratios of both true positive and true negative were improved by approximately 19% (62-81%) compared with the conventional "chemical shift-only" method.