The problems associated with using the Karplus parameters for Gly 3 are discussed in Section S9 of the Supporting Information and elsewhere. Therefore, we evaluate the backbone conformations of Gly 3 through its φ/ψ distribution alone. In Figure , the OPLS-AA/M backbone conformational distribution is compared to that obtained using the QUBE force field. A lower α-helical population is occupied by the QUBE force field, but otherwise both distributions are very similar.