title: Characterization of intermediate state of myoglobin in the presence of PEG 10 under physiological conditions.
abstract: The macromolecular crowding progressively has been gaining prominence in recent years as it acts as a sword with double-edge on protein stability and folding, i.e., showing assorted results of having both stabilizing and destabilizing effects. We studied the effects of different concentrations of polyethylene glycol (PEG-10) on structure and stability of myoglobin. The tertiary structure of myoglobin was found to be perturbed in the presence of polyethylene glycol, however there was insignificant change in the secondary structure. It was observed that polyethylene glycol induces molten globule state in myoglobin, where the intermediate state holds hydrophobic patches and larger hydrodynamic volume as compared to the native protein. In addition, isothermal titration calorimetry (ITC) showed strong binding between myoglobin and polyethylene glycol, at the physiological pH. We hypothesize that polyethylene glycol induces molten globule conformation in myoglobin by interacting with heme group of myoglobin. We caution that the binding of protein with crowder and other soft interactions need to be gravely well thought-out when studying macromolecular crowding. In our case, destabilizing protein-crowder interactions could compete and overcome the stabilizing exclusion volume effect.
authors.affiliation: Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025, India.
authors.forename: Zahoor Ahmad
authors.initials: ZA
authors.lastname: Parray
authors.affiliation: Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025, India.
authors.forename: Sumra
authors.initials: S
authors.lastname: Shahid
authors.affiliation: Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025, India.
authors.forename: Faizan
authors.initials: F
authors.lastname: Ahmad
authors.affiliation: Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025, India.
authors.forename: Md Imtaiyaz
authors.initials: MI
authors.lastname: Hassan
authors.affiliation: Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025, India. Electronic address: asimulislams@gmail.com.
authors.forename: Asimul
authors.initials: A
authors.lastname: Islam
mesh_terms: D000818:Animals; D006736:Horses; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D009211:Myoglobin / Q000737:chemistry* / Q000378:metabolism; D011092:Polyethylene Glycols / Q000378:metabolism / Q000494:pharmacology*; D055550:Protein Stability / Q000187:drug effects
chemical_list: D009211:Myoglobin; D011092:Polyethylene Glycols
keywords: Circular dichroism; Isothermal titration calorimetry; Macromolecular crowding; Molten globule; Myoglobin; Protein folding