He substitution of valine for glutamate at position 6 of the  chains of hemoglobin places a nonpolar residue on the outside of hemoglobin S, the version of hemoglobin that is responsible for sickle-cell anemia. The oxygen affinity and allosteric properties of hemoglobin are virtually unaffected by this change. However, the valine side chain of hemoglobin S interacts with a complementary sticky patch (formed by phenylalanine 85 and leucine 88) on another hemoglobin molecule – a patch that is exposed in deoxygenated but not in oxygenated hemoglobin. a) What is the chemical basis for the interaction between the hemoglobin molecules? b) What would be the effect of this interaction?