For an amino acid such as aspartic acid, what impact would you expect a neighboring carboxylic acid to have on the apparent pKa value of the side chain?

The apparent pKa value for aspartic acid increases

Explanation:

The apparent pKa value for aspartic acid increases. Due to the presence of one negative in close proximity to another negative charge, it causes charge-to-charge repulsion which in turn leads to the increase in pKa values.