In this section we would like to consider a bisubstrate (𝑆 and 𝑆 ) ping pong mechanism (Scheme 2) since it is frequently encountered in bioelectrochemical sensors. Two versions of ping pong mechanism will be considered: (i) one denoted PP in the following when 𝑘 = 0 as more often considered and (ii) the general case, denoted PI hereafter, when 𝑘 > 0, mechanisms such as the one detailed in Scheme 2 are often approximated by a canonical Michaelis-Menten MM mechanism (Scheme 1) . However, this supposes that the first step of the Scheme 2 is globally irreversible , i.e., 𝑘 [𝑄] ≈ 0, and also that the second step is infinitely fast relative to the first one. Despite the fact that this approximation is often used we wish therefore to separate their analyses in the following depending on whether or not 𝑘 [𝑄] has a negligible kinetic role.