Amino acids are zwitterion The protonation state of alanine pk of COO-close to 2.34 pk of NH3+near 9.69 Alanine 14.0 12.0h pK2=9.69 10.0 H2N-H CH3 8.0 8.0- pH>10 pH<2 or pH>9 02 6.0 =601 6.0- HgN-H cation?anion? 4.0 4.0 CH3 pH between 2 to 9? pKg1=2.34 pH≈6 2.0 2.0 9C02H H3N-H CH3 0.5 1.0 1.5 2.0 2.5 <2 Equivalents of OH" pl=1/2(pkaCOOH+pkaNH3+) The zwitterion of alanine is the predominant form in the pH range from 2.3 to 9.9Amino acids are zwitterion The zwitterion of alanine is the predominant form in the pH range from 2.3 to 9.9 pk of COO- close to 2.34 pk of NH3+ near 9.69 pH<2 or pH> 9 cation? anion? pH between 2 to 9? The protonation state of alanine pI=1/2(pkaCOOH+pkaNH3+)