Before revision:  For kinesin-1, \mathcal{Q} \muM  is locally minimized at [ATP] \approx 200 \muM and f\approx 4 pN. Remarkably, for the mutant with a longer neck-linker this local minimum vanishes , and the energetic cost to achieve the same precision as the wild-type increases significantly , which underscores the importance of molecular structure in transport properties.
After revision:  For kinesin-1, \mathcal{Q} approaches the theoretical bound at f\approx 4 pN and over a broad range of ATP concentration (1\muM is locally minimized at [ATP] \approx 200 \muM and f\approx 4 pN. Remarkably, for the mutant with a longer neck-linker this local minimum vanishes , and the energetic cost to achieve the same precision as the wild-type increases significantly , which underscores the importance of molecular structure in transport properties.