Structural change of myoglobin structure after binding with spermidine

Abstract

Myoglobin is the iron-rich protein of 153 or 154 amino acid residues, comprising a prosthetic group of heme (iron-containing porphyrin). It is responsible for the reversible binding and transporting of molecular oxygen in muscle tissue. There are proximal and distal histidine groups. The proximal His group joined specifically to the iron center and a distal histidine group on the inverse confront, not bonded to the iron. Horse heart myoglobin contains two tyrosine residues and two tryptophan residues. Multi-spectroscopic, thermodynamic, molecular docking, and molecular dynamics simulations were used in the present study to investigate the variations instability, structure, and function of horse heart myoglobin (Mb) in the presence of polyamine spermidine. Reports from the different experiments have shown that spermidine is bound to myoglobin. Steady-state fluorescence analysis showed a static quenching system as the primal quenching mechanism in the myoglobin − spermidine interaction, which is confirmed by UV − Visible and molecular docking studies. Thermodynamic and molecular docking findings demonstrate spermidine binding to myoglobin is driven mainly by van der Waals force and hydrogen bonding forces. The CD spectrum showed the secondary variation in myoglobin structure with a rise in α-helicity after ligand binding and a small decrease in myoglobin β-sheet after.