The pK _ a values for the ionisable groups of aspartic acid are given in the structure below. Identify the major species present in an aqueous solution at pH = 7.2 .

Step-by-step solution

The protonation state of an ionisable group in an amino acid depends on the pH of the solution relative to its pK _a value. If pH > pK _a , the group exists predominantly in its deprotonated form. If pH Given the pH of the solution is 7.2 : 1. For the - COOH group, pK _a = 2.10 . Since 7.2 > 2.10 , it will be deprotonated to - COO ^- . 2. For the side-chain - COOH group, pK _a = 3.86 . Since 7.2 > 3.86 , it will also be deprotonated to - COO ^- . 3. For the - NH ₃^+ group, pK _a = 9.82 . Since 7.2 Therefore, the ma