Question

In sickle hemoglobin, the Valine 6 on the β globin from another hemoglobin molecule can interacts with the hydrophobic pocket. (see diagram) 2B-1pt) What is the most likely type of interaction between valine 6, phenylalanine 85 and leucine 88? Your choices are: ‘a covalent bond’, ‘an ionic bond’, ‘a hydrogen bond’, ‘a hydrophobic interaction’. Explain why.

Answer 1

In sickle cell hemoglobin, there is A HYDROPHOBIC INTERACTION is present between valine, phenylalanine,and leucine.

Because these 3 amino acids are hydrophobic amino acids. Being hydrophobic these amino acids will occur in the core part of globular protein away from water (hydrophilic environment). So in case of sickle cell hemoglobin also these will interact through hydrophobic interaction. In mutant hemoglobin, it will make hydrophobic pocket.

A covalent bond is always in formation of primary structure of biomolecule. e.g .peptide bond so it is not correct answer.

For Hydrogen bond formation in protein structure interaction with water is involved. As hydrophobic amino acids cannot interact with water. Hydrogen bond is incorrect answer.

For formation of Ionic interaction like salt bridges, charged amino acids like Lysine, Arginine , GLUTAMIC ACID are involved. So ionic interaction is incorrect answer. Salt bridges are present in normal hemoglobin.

Hence correct answer is HYDROPHOBIC INTERACTION.