Effects of Ethylene Glycol on the Structure and Stability of Myoglobin Using Spectroscopic, Interaction, and In Silico Approaches: Monomer Is Different from Those of Its Polymers

Zahoor Ahmad Parray; Faizan Ahmad; Md Imtaiyaz Hassan; Ikramul Hasan; Asimul Islam

doi:10.1021/acsomega.0c01185

Effects of Ethylene Glycol on the Structure and Stability of Myoglobin Using Spectroscopic, Interaction, and In Silico Approaches: Monomer Is Different from Those of Its Polymers

ACS Omega. 2020 Jun 2;5(23):13840-13850. doi: 10.1021/acsomega.0c01185. eCollection 2020 Jun 16.

Authors

Zahoor Ahmad Parray¹, Faizan Ahmad¹, Md Imtaiyaz Hassan¹, Ikramul Hasan², Asimul Islam¹

Affiliations

¹ Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025, India.
² Department of Basic Medical Science, Faculty of Applied Medical Sciences, Al-Baha University, Al-Baha 110025, KSA.

Abstract

Investigation of changes in thermal stabilities and structures of proteins in the presence of different co-solutes (ligands) is an integral part in the basic research, discovery, and development of drugs. Ethylene glycol (EG) is known to be toxic and causes teratogenic, inducing primarily skeletal and external malformations and other diseases. The effect of EG on the structure and thermal stability of myoglobin (Mb) was studied using various spectroscopic techniques at pH 7.0 and two different temperatures. As revealed by circular dichroism, Trp fluorescence, nano-DSF, and absorption (UV and visible) measurements, EG (i) has no significant effect on secondary and tertiary structures of Mb at 25 °C, and (ii) it decreases the thermal stability of the protein, which increases with increasing concentration of EG. As revealed by ANS (8-anilino-1-naphthalene sulfonic acid) fluorescence measurements, heat-induced denatured protein has newly exposed hydrophobic patches that bind to ANS. Isothermal titration calorimetry revealed that the interaction between EG and Mb is temperature dependent; the preferential interaction of EG is entropy driven at low temperature, 298 K (25 °C), and it is enthalpy driven at higher temperature, 343 K (70 °C). Molecular docking study showed that EG interacts with side chains of amino acid residues of Mb through van der Waals interactions and hydrogen bonding.