title: Chitosan-myristate nanogel as an artificial chaperone protects neuroserpin from misfolding.
abstract: BACKGROUND
  Molecular chaperon-like activity for protein refolding was studied using nanogel chitosan-myristic acid (CMA) and the protein neuroserpin (NS), a member of the serine proteinase inhibitor superfamily (serpin).
  
  
  METHODS
  Recombinant his-tag fusion NS was expressed inEscherichia coli. For confirmation of refolding of the purified NS, structural analysis was performed by circular dichroism and spectrofluorometric along with its inhibitory activity, which was assayed by single-chain tissue plasminogen activator. For evaluating NS aggregation during preparation, the samples were separated on a 7.5% (w/v) nondenaturing polyacrylamide gel electrophoresis. MA and chitosan covalently join together by the formation of amide linkages through the 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide-mediated reaction. The morphology and size of the prepared CM nanogel were characterized by transmission electron microscopy and scanning electron microscopy.
  
  
  RESULTS
  Heating at different temperatures (25°C, 37°C, 45°C, 65°C, 80°C) results in a further rise in β-structures accompanied by a fall of helices and no significant change in random coils. Structural changes in NS in the presence of CMA nanogel were less than that in the absence of CMA nanogel. Mater nanogel effectively prevented aggregation of NS during temperature induced protein refolding by the addition of cyclodextrins. The nanogel activity resembled the host-guest chaperon activity.
  
  
  CONCLUSIONS
  These conditions, called conformational disorders, include Alzheimer's, Parkinson's, Huntington's disease, the transmissible spongiform encephalopathies, prion diseases, and dementia. Nanogels can be useful in recovery of the structural normality of proteins in these diseases.
authors.affiliation: Department of Biochemistry, Payam Noor University, Tehran, Iran.
authors.forename: Habib
authors.initials: H
authors.lastname: Nazem
authors.affiliation: Department of Clinical Biochemistry, Tarbiat Modares University, Tehran, Iran.
authors.forename: Afshin
authors.initials: A
authors.lastname: Mohsenifar
authors.affiliation: Young Researchers and Elite Club, Tehran Medical Sciences Branch, Islamic Azad University, Tehran, Iran.
authors.forename: Sahar
authors.initials: S
authors.lastname: Majdi
keywords: Cyclodextrin; misfolding; nanogel (chitosan-myristic acid); neuroserpin