The two α-helices present in 1BUJ, around residue 10 and residue 30, are generally well represented with the QUBE force field. However, in regions with no structure, a bend, or a turn significant deviations from experiment are observed and the RMSD reaches extremely high values. By way of comparison, the backbone RMSD using the AMBER ff15ipq force field was 3.4 Å after 10µs of simulation, and after 0.5 µs was approximately 3 Å. In the AMBER ff15ipq work, the high RMSD was attributed to variability in the loop regions, which had also been observed in experimental structures. Closer examination of the φ/ψ distributions of each residue reveal the difficulty of capturing accurate conformational preferences. For example, the NMR ensemble for Lys38 shows the presence of both β-sheet and α-helical conformations. These are also observed in MD simulations using both AMBER ff15ipq and the QUBE force field, but the proportion of each conformation is different. The ensemble of Ser66 is not well represented with AMBER ff15ipq, but with the QUBE force field all structures in the ensemble are captured to some degree, although an additional α-helical conformation is also observed.