Elastic property of sickle and normal hemoglobin protein: Molecular dynamics

Abstract

This work focuses on identifying the conformational stability and binding components in sickle and normal hemoglobin to explore the elastic properties and realize the stiffness by using molecular dynamics simulation. Our investigation shows that a larger force is required to separate the beta chain of normal hemoglobin in comparison to the sickle hemoglobin by using steered molecular dynamic. In sickle hemoglobin protein (HbS), the hydrogen bond binding force of the beta chain is 7073.74–12 646.80 pN for pulling velocities of 0.000 20–0.000 40 nm/ps with the spring constant of 800 kcal mol−1 nm−2. Similarly, in normal hemoglobin protein, the hydrogen bond binding force in the beta chain ranges from 12 005.00 to 17 753.70 pN for the same values of pulling velocities and spring constant. This indicates that the normal hemoglobin is stiffer than sickle hemoglobin. We have also analyzed the solvent accessible surface area (SASA) of both proteins, and our investigation shows that the SASA of normal hemoglobin is much less than that of sickle hemoglobin because of the sickled structure of HbS. We have also studied the van der Waals (vdW), electrostatic, hydrophobic, and salt bridge interactions in both kinds of hemoglobin. The sum of vdW, electrostatics, and hydrophobic interactions in HbS is higher, whereas salt bridge interactions are found lower in sickle normal hemoglobin proteins than in normal hemoglobin protein.