As noted above however, there are systems or regions of systems where sidechain transitions are slow and the benefit of applying enhanced sidechain sampling methods can perhaps in some cases outweigh the costs. In the interior of proteins (e.g. as in the case of the valine 111 sidechain in the widely-studied L99A mutant of T4 lysozyme ) the barrier to rotation can be >10kcal/mol due to tight packing of the surroundings such as neighboring sidechains. To assess the relative performance of BLUES versus MD when barrier heights are higher (such as when torsional rotation is hindered by steric interactions with the surroundings) we updated our model system to have a higher barrier to sidechain rotation. Specifically, by artificially increasing the maximum torsional barrier of the valine χ 1 to roughly 10 kcal/mol, we can use the valine-alanine system as a test case for BLUES sidechain sampling.