Some examples include Protonation is a fundamental chemical reaction and is a step in many stoichiometric and catalytic processes.
Some ions and molecules can undergo more than one protonation and are labeled polybasic, which is true of many biological macromolecules.
Protonating or deprotonating a molecule or ion can change many other chemical properties, not just the charge and mass, for example solubility, hydrophilicity, reduction potential or oxidation potential, and optical properties can change.
[2] Enantioselective protonations are under kinetic control, are of considerable interest in organic synthesis.
Many enzymes, such as the serine hydrolases, operate by mechanisms that involve reversible protonation of substrates.