The measurement and interpretation of relaxation data on macromolecules present special problems. The required instrumental conditions and extensions of relaxation theory are outlined and illustrated by the analysis of <sup>13</sup>C and <sup>1</sup>H relaxation data on a small protein (bovine pancreatic trypsin inhibitor).
A. Ribeiro, N. G. Wade-Jardetzky, R. King, and O. Jardetzky, "The Study of Macromolecular Dynamics by High Resolution NMR," Appl. Spectrosc. 34, 299-305 (1980)