Second, for the alanine polypeptides (see Section 3.2) we have employed second order Møller-Plesset perturbation theory (MP2) calculations with Ahlrich's def2-SVP basis set using the Turbomole program package (Version 7.5.1) . Third, for the calculations on different conformers of 2LYW (see Section 3.3), we used the PBEh-3c method as implemented in Orca (Version 5.0.3) in combination with a conductor-like polarizable continuum model (C-PCM) , in which default parameters for water were applied.