The catalyzed reduction of quinones by DI is a well-established "ping-pong" mechanism, which under turnover conditions can be defined by two half enzyme reactions (and three rate constants), i.e. (i) a two-step Michaelis-Menten type reaction between NADH and the oxidized form of the enzyme (characterized thus by a Michaelis-Menten constant KM and a catalytic turnover rate constant kc) and (ii) a bimolecular reaction characterizing the obligatory two-electron transfer reduction of quinones (here the 1,4-NQ) by the reduced form of the enzyme (governed thus by a second-order rate constant kred). The coupling of this enzymatic "ping-pong" mechanism to the H2O2-mediated deprotection of P3 leads to the autocatalytic set of reactions S10 to S16 in SI. To simulate this mechanism, we first used for Loop 2 the values of KM, kc and kred (i.e., 60 µM, 1200 s -1 , 1.5 × 10 9 M -1 •s -1 , respectively) previously determined by us for an analogue of the 1,4-NQ, i.e. the menadione, while the other rate constants associated to Loop 1 were the same as those above determined (for clarity, the list of rate constants are gathered in the entry 1 of Table ). The simulated time course of NADH consumption at different H2O2 concentrations are shown in Figure . Their sigmoidal shapes are, as expected, in agreement with an autocatalytic reaction and also similar with those obtained experimentally (Figure ). However, a main issue is that their t1/2 do not match those obtained experimentally, differing by a factor as high as 28. This result indicates that something is missing in the proposed mechanism. We figured out that it might be due to our oversimplified description of the autoxidation of 1,4-NQ. It is well established that the autoxidation mechanism of hydroquinones is more complex than a simple bimolecular reaction. It is indeed an autoinductive radical chain mechanism, in which the semiquinone (Q •-) and anion superoxide are involved as chain propagating species as follow: