Potentials of mean force. We next compare the conformational free energy profiles obtained from msesMD simulation of sLe a with those computed via other biasing methods. Firstly, in order to observe the rotational barrier along the F 1 → F 4 transition, a 1-dimensional potential of mean force was computed using umbrella sampling around the ψ F torsion angle of sLe a , ie. ψ of the Fucα(14)GlcNAc. This involved computing 120 windows of 20 ns production dynamics each. As expected, for this free energy profile, the closed form C is predicted as the lowest energy conformation, occupying the F 1 well (Figure ). On this profile we also observe other local minima: F 2/3 (we group F 2 and F 3 as they occupy similar positions along ψ) and F 4 . The F 2/3 and F 4 wells have calculated free energies relative to F 1 of 3.2 and 2.8 kcal mol -1 (Figure ).