When a molecule with acidic protons enters into an environment with a pH value that is greater than the pK, of its functional groups, the molecule will lose the proton(s) in question. Consider the structure of the amino acid histidine in its fully protonated form. How would the amino acid appear in a slightly basic environment of pH 8, given the following structure and the pK, values of the acidic protons? Bear in mind, that when the pH of the solution is greater than the pK, of the proton, that proton will be lost. proton pK
Ha 1.8
Hb 9.2
Hc 6.0