title: Counter ion induced irreversible denaturation of hen egg white lysozyme upon electrostatic interaction with iron oxide nanoparticles: a predicted model.
abstract: The effects of electrostatic interaction between the hen egg white lysozyme (HEWL) and the functionalized iron oxide nanoparticles (IONPs) have been investigated using several techniques, e.g., CD, DSC, ζ-potential, UV-visible spectroscopy, DLS, TEM. Nanoparticles (IONPs) were functionalized with three hydrophilic ligands, viz., poly(ethylene glycol) (PEG), trisodium citrate (TSC) and sodium triphosphate (STP); where both TSC and STP contain Na(+) counter ions. It has been observed that the secondary structure of HEWL was not affected by PEG functionalized IONPs, but was partially and almost completely perturbed by TSC and STP functionalized IONPs, respectively. The perturbation of the secondary structure was irreversible. We have predicted an interaction model to explain the origin of perturbation of HEWL structure. We have also investigated the stability of nanoparticles dispersions after interaction with HEWL and used the DLVO theory to explain results.
authors.affiliation: UGC-DAE Consortium for Scientific Research, Trombay, Mumbai 400085, India. ghoshg@csr.res.in
authors.forename: Goutam
authors.initials: G
authors.lastname: Ghosh
authors.forename: Lata
authors.initials: L
authors.lastname: Panicker
authors.forename: R S
authors.initials: RS
authors.lastname: Ningthoujam
authors.forename: K C
authors.initials: KC
authors.lastname: Barick
authors.forename: R
authors.initials: R
authors.lastname: Tewari
mesh_terms: D000818:Animals; D002152:Calorimetry, Differential Scanning; D002645:Chickens; D002942:Circular Dichroism; D005290:Ferric Compounds / Q000378:metabolism*; D007477:Ions; D008956:Models, Chemical; D009113:Muramidase / Q000737:chemistry / Q000378:metabolism*; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D011489:Protein Denaturation; D017433:Protein Structure, Secondary; D015203:Reproducibility of Results; D017550:Spectroscopy, Fourier Transform Infrared; D055672:Static Electricity; D013499:Surface Properties; D013997:Time Factors; D044366:Transition Temperature
chemical_list: D005290:Ferric Compounds; D007477:Ions; C000499:ferric oxide; C421864:hen egg lysozyme; D009113:Muramidase