Rotating frame spin-lattice relaxation experiments and the problem of intramolecular motions of peptides in solution

The application of rotating frame spin-lattice relaxtion to the determination of the intramolecular motions in peptides is discussed, and results are presented on the application of ¹³C T_1p to peptide microdynamics in solution. The effective molecular rotational reorientation times at the amide and amino nitrogens may be derived from appropriate data onT_1p of the carbons adjacent to them. We also show by theoretical caculations that ¹H and ¹³C T_1p experiments of suitable ²H and ¹⁵N substituted peptides will allow intramolecular main- and sidechain motions, characterized by times in the range 10^?1–10^?6 sec, to be investigated.