Why would a drop in blood pH have an undesirable effect on the proximal histidine's function?a. A drop in pH would make deprotonation more likely, and a deprotonated proximal histidine would be able to hydrogen bond to O2 to stabilize its binding to the heme. b. A drop in pH would make protonation more likely, and a protonated proximal histidine would not be able to donate its electron density to the iron atom. c. A drop in pH would make protonation more likely, and a protonated proximal histidine would not be able to hydrogen bond to O2 to stabilize its binding to the heme due to its positive charge.

c. A drop in pH would make protonation more likely, and a protonated proximal histidine would not be able to hydrogen bond to O2 to stabilize its binding to the heme due to its positive charge.

Explanation:

Protonation refers to the addition of proton or H+ to the atom or molecule. If the pH of blood drop means acidic so it causes adverse effect on the function of proximal histidine because the proximal histidine gain proton and become cation. Due to this proton, proximal histidine is unable to make hydrogen bond between heme and oxygen and the blood is unable to transport more oxygen with hemoglobin from the lungs.