Now, let's actually focus on the seven amino acids that have ionized the bulk side chain groups. So let's begin with aspartic acid and glutamic acid. Now, both of these acids, both of these amino acids contain a side chain group that contains a carboxylic acid. And the PKA value of this carboxylic acid is 4.1. So what that means is if we're at 4.1, we'll have 50% of the acid and 50% of the conjugate base. If we're below a PH of 4.1, this will predominate.