SIDE-CHAIN MOTION WITH 2 DEGREES OF FREEDOM IN PEPTIDES - AN NMR-STUDY OF PHENYLALANINE SIDE-CHAINS IN ANTAMANIDE

The potential of relaxation measurements for the detailed study of sid e-chain dynamics of peptides is explored. As a test case, the phenylal anine side chains with two rotational degrees of freedom in the cyclic decapeptide antamanide have been selected for the study. Various comb inations of motional models, such as discrete jump and rotational diff usion models, have been considered for the two degrees of freedom. Alt hough some ambiguity in the assignment of the different motional model s remains, valuable information on the detailed side-chain dynamics ca n be obtained.