Question #44970

The tertiary structure of a globular enzyme is critically stabilized by a buried intramolecular salt bridge between a Glutamic acid residue (side chain $pK_{a1} = 4.0$) and a Histidine residue (side chain $pK_{a2} = 6.0$). Assuming the ionizations of these side chains are independent, the enzyme is subjected to a pH shift from its optimum pH (where the probability of the intact salt bridge is maximized) to a highly acidic pH of 2.0 at 298 K, resulting in irreversible denaturation due to the disruption of electrostatic interactions.

Determine the optimum pH for the salt bridge, the approximate percentage of the salt bridge that remains intact at pH 2.0, and the dominant electrostatic state of the (Glutamic acid, Histidine) side chains at pH 2.0, respectively.