THE WORLD OF PROTON PUMPS Nathan Nelson uite frequently an observer looks at a life phenomenon and asks himself why nature took this route out of several other available mec anisms. In order to understand this challenge he may first try to reconstruct the evolution of the process taking into account the main driving forces that were assumed to exist during the last 3. 5 billion years on earth. Now we know that the electrochemical gradient of protons is the universal high-energy intermediate produced and uti lized by every living cell in nature. This high energy intermediate is an expression...