ABSTRACT
The addition or removal of protons (hydrogen ions)—rapid chemical reactions-modify the physical properties of macromolecules and alter the kinetics of nonenzymatic reactions. pH homeostasis is critically regulated in human organ systems to physiological advantage, although certain organs tolerate wider fluctuations in pH than others. For example, acidity is used in innate antimicrobial defense (1,2) in the stomach, where the gastric mucosa is protected from acid injury by barrierforming and buffer-enhancing macromolecules (3), while blood pH requires such strict regulation that deviation by one pH unit results in death.
