The dynamic properties of melittin in solution. Investigations by NMR and molecular dynamics

Molecular dynamics simulations are described for the peptide melittin. The atomic trajectories are calculated both with normal potential energy functions and with additional distance restraints deduced from nuclear Overhauser effects observed in NMR experiments. The results are compared with NMR data on coupling constants and amide exchange rates and with B-factors from X-ray crystallography. The observed correlations between experiment and molecular dynamics simulations suggest a relatively mobile C-terminus and relatively high flexibility around residue 11. It is noted that the high conformational variation around residue 11 is due in part to the presence of a proline at position 14 which results in a "missing" H-bond in the largely alpha-helical structure. It is also noted that a proline is a common feature of many putative membrane spanning helices. A role for such prolines is suggested.