Molecules that contain two coupled reactive sites are simple chemical systems that may nevertheless already exhibit some complex behaviors when they are subjected to suitable external constraints. This report first proposes a theoretical model and an experimental illustration to demonstrate that the introduction of an auxiliary reactive site on a substrate can lead to local and continuous tuning of the thermodynamic and kinetic properties of a reaction of interest. It is then shown that a similar kinetic scheme that is appropriate for describing the evolution of concentrations in a two-site catalysis exhibits diverse properties when maintaining the system far from equilibrium and varying the order of magnitude of the rate constants: tuning of chemical yield, autocatalysis, and kinetic proofreading are obtained.