DYNAMICS OF HETEROPOLYMERS IN DILUTE-SOLUTION - EFFECTIVE EQUATION-OF-MOTION AND RELAXATION SPECTRUM

The dynamics of a heteropolymer chain in solution is studied iu the li mit of long chain length. Using a functional integral representation, we derive an effective equation of motion, in which the heterogeneity of the chain manifests itself as a time-dependent excluded-volume effe ct. At the mean-field level, the heteropolymer chain is therefore dyna mically equivalent to a homopolymer chain with both time-independent a nd time-dependent excluded volume effects. The perturbed relaxation sp ectrum is also calculated. We find that heterogeneity also renormalize s the relaxation spectrum. However, we find, to the lowest order in he terogeneity, that the relaxation spectrum does not exhibit any dynamic freezing at the point when static (equilibrium) ''freezing'' transiti on occurs in heteropolymer. Namely, the breaking of fluctuation-dissip ation theorem proposed for spin-glass dynamics does not have a dynamic effect on the heteropolymer as far as the relaxation spectrum is conc erned. The implication of this result is discussed.