Which of the Following Is a Characteristic of Hemoglobin

Multiple Choice

Which of the following is a characteristic of hemoglobin?

A) It is composed of four identical polypeptide chains.
B) There is one heme group per active Hb molecule.
C) Oxygen and carbon dioxide compete for the same binding site on heme.
D) It is an elongated, fibrous-type protein, hence is not very soluble in water.
E) Binding of oxygen to Hb results in change in the pKa of certain histidine residues toward lower values.