INFLUENCE OF SOLVATION ON HELIX FORMATION OF POLY-ALANINE STUDIED BY MULTIPLE ANNEALING SIMULATIONS

The influence of solvation on a-helix formation is studied for a 14-re sidue homoalanine and a 16-residue alanine-based polypeptide, in aqueo us solution. Four variants of Dynamic Monte Carlo (DMC) simulations, u sing a multiple annealing procedure are performed. The results obtaine d under in vacuo conditions are compared to simulations considering ei ther contributions to the solvation energy of non-favourable solvent i nteractions by hydrophobic groups, or the total solvation energy, both calculated by a continuum approximation. The highest average helix le ngths are found when the total solvation energy (hydrophilic and hydro phobic contributions) is considered, although solvation counteracts th e formation of compact peptide structures. The influence of solvation on helix formation is discussed.