The number 6.5 in GOLD PLP score difference appears several times in this work. First, amongst a broad range of IC50 experiments, the binding affinity changes by a factor of approximately 10, and given a 1 kcal difference generating leads to 6.5 to 1 kcal. The value at room temperature 298 K of exp(1/𝑘 𝐵 𝑇 ) is also 6.5. Docking score is dimensionless and not energy, but a linear interpolation is made using this heuristic relation.