Loop-closure () and relaxation () time constants for the unlabelled peptides

The autocorrelation functions G() (Eq. 1) of the unlabelled peptides decay by –15% in the first 3 ps, in agreement with femtosecond-timescale spectroscopic data [29] and previous MD results [70]. Beyond 3 ps the curves are fitted using the following function: . Correlation coefficients were higher than 0.95 and the lower than 15. On the 3–500 ps timescale a complex (non-exponential) decay is observed (, ), again in agreement with experiment [29], corresponding to a distribution of relaxation times which is found to result from a range of processes, including rotation around single bonds and breaking and forming of intra-chain hydrogen bonds (space restrictions preclude a detailed description of these processes). On the nanosecond timescale one exponential relaxation (, ) for chains with and 3 and two exponential relaxations (, and , ) for chains with , 7, 9 and 12 are observed. and are obtained using Eq. 3. Errors reported in parenthesis are one standard deviation as obtained by dividing each trajectory into two halves.