Comments to the Editor. Reply to the Comment by V.P. Shkilev on "Anomalous versus slowed-down Brownian diffusion in the ligand-binding equilibrium"

International audienceIn his comment in this issue of the Biophysical Journal, V.P. Shkilev (1) disagrees with some of the findings of our article on the influence of diffusion on the ligand-binding equilibrium (2). V.P. Shkilev makes two main claims in his comment: (i) when diffusion is uniformly Brownian (with a space-independent diffusion coefficient), "the equilibrium fraction of bound receptors [...] should depend on the dif- fusion coefficient" and (ii) when molecules undergo tran- sient subdiffusion due to a Continuous-Time Random Walk (CTRW), the equilibrium fraction of bound receptors can only be equal or larger (but not smaller) than the value ex- pected for uniform Brownian motion with comparable dif- fusion coefficient. While the former is a frequent miscon- ception related to the ligand-binding equilibrium, the lat- ter relates to an important issue in the field of (anomalous) subdiffusion-reaction couplings