For this system, we have also chosen to freeze atoms during the NCMC simulation to reduce the added computational cost and increase the acceptance of proposed moves. The freeze distance parameter was set to 5Åsuch that all atoms located 5Åor more from the sidechain were immobilized during the NCMC portion of the BLUES simulation. Further simulation details available in scripts deposited in SI. General information about the function of nprop, freeze distance and other parameters can be found in the GitHub repository for BLUES () and in the BLUES documentation ().