Hydrogen pump, H+/K+-ATPase, and inhibitors
Hydrogen is the most abundant element of the universe in which it is present in the form of two stable isotopes, hydrogen itself predominant, of atomic mass 1, and deuterium at trace levels. The radioactive isotope of hydrogen is tritium which has a 12 years half-life.
In molecular form, H2, hydrogen is the lightest of all gases and diffuses very easily. There is little molecular hydrogen in the breath, coming especially from intestinal fermentations.
The hydrogen molecule can give two protons and two electrons according to the reaction:
The E0 redox potential of this equilibrium is taken as reference and has the 0 value. The redox potentials are expressed in volt compared to that of hydrogen, the negative values correspond to reductants and the positive values to oxidants. The proton when bound to a water molecule gives H3O+ or hydronium ion.
In atomic form, hydrogen is a constituent of already all molecules of the body.
The atom of hydrogen of water and many organic molecules plays a crucial role by establishing bonds called hydrogen bonds which are sometimes intramolecular and generally intermolecular. The hydrogen bonds stabilize the structure of biological molecules.
The proton is the first source of energy because mitochondria are proton pumps. The oxidation of substrates during respiration leads to the expulsion of protons out of mitochondria, creating a sufficient electrochemical potential to supply the energy necessary for the synthesis of ATP by the mitochondrial ATP-synthase.
The proton is the acidifying agent, secreted by the H+/K+-ATPase pump in the gastric fluid.