For example: amino acids that are floating around, some with charge at physiological pH. My question is what exactly do the charged amino acids form a salt with? other amino acids? sugars? fatty acids? whatever happens to have an opposite charge and is close? A rephrasing: I am thinking about how how in o chem acid base reactions we added sodium hydroxide to a solution of benzoic acid to create the conjugate base of benzoic acid. In the case the benzoic acid forms a salt with the sodium, so what do the amino acids form salts with in vivo?