The bc1 complex is an enzyme that plays a fundamental role in the energy production mechanisms of all living cells. In this talk, I will present the results of our investigations, aimed at elucidating the initial steps of its reaction mechanism. Based on molecular dynamics simulations and quantum chemistry calculations of the bc1 complex from the photosynthetic purple bacterium, we were able to identify key elements involved in the primary proton-coupled electron transfer reactions that take place upon its complex activation.