We test a theory for the long time conformational dynamics of the penta-peptide Met-enkephalin by comparison with the explicit solvent molecular dynamics and implicit solvent Langevin dynamics simulations described earlier. Using the requisite equilibrium averages computed from these simulations and friction coefficients evaluated from shorter simulations obtained with the Pastor-Karplus scheme, the generalized Rouse and mode-coupling theory (MCT) generate a variety of time-correlation functions that probe both local and global dynamics. The comparison between different levels of MCT calculations demonstrates that the smallest eigenvalues (corresponding to the relaxation rates of the slowest modes) are insensitive to the choice of the high frequency coupled modes. Compared with the direct simulations, the MCT time correlation functions for the dynamics involving the motion of certain rigid groups, such as end-to-end, interphenyl vector or certain vectors between bonded backbone atoms, often exhibit a too rapid short time decay but an excellent representation of the long time relaxation rate. Thus, the MCT demonstrates its ability to predict the long time dynamics of solvated peptides using only atom friction coefficients and equilibrium averages, which are easier to simulate than the long time trajectories that are usually employed for probing dynamics with either explicit or implicit solvent descriptions. (C) 2003 American Institute of Physics.