title: Stability and biological activity evaluations of PEGylated human basic fibroblast growth factor.
abstract: BACKGROUND
  Human basic fibroblast growth factor (hBFGF) is a heparin-binding growth factor and stimulates the proliferation of a wide variety of cells and tissues causing survival properties and its stability and biological activity improvements have received much attention.
  
  
  METHODS
  In the present work, hBFGF produced by engineered Escherichia coli and purified by cation exchange and heparin affinity chromatography, was PEGylated under appropriate condition employing 10 kD polyethylene glycol. The PEGylated form was separated by size exclusion chromatography. Structural, biological activity, and stability evaluations were performed using Fourier transform infrared (FITR) spectroscopy, 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide (MTT) assay and effect denaturing agent, respectively.
  
  
  RESULTS
  FITR spectroscopy revealed that both PEGylated and native forms had the same structures. MTT assay showed that PEGyalated form had a 30% reduced biological activity. Fluorescence spectrophotometry indicated that the PEGylated form denatured at higher concentrations of guanidine HCl (1.2 M) compared with native, which denatured at 0.8 M guanidine HCl.
  
  
  CONCLUSIONS
  PEGylation of hBFGF makes it more stable against denaturing agent but reduces its bioactivity up to 30%.
authors.affiliation: Department of Quality Control, Research and Production Complex, Pasteur Institute of Iran, Karaj, Iran.
authors.forename: Shahin
authors.initials: S
authors.lastname: Hadadian
authors.affiliation: Department of Pilot Biotechnology, Pasteur Institute of Iran, Tehran, Iran.
authors.forename: Dariush Norouzian
authors.initials: DN
authors.lastname: Shamassebi
authors.affiliation: Department of Medical Biotechnology, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran.
authors.forename: Hasan
authors.initials: H
authors.lastname: Mirzahoseini
authors.affiliation: Department of National Cell Bank, Pasteur Institute of Iran, Tehran, Iran.
authors.forename: Mohamad Ali
authors.initials: MA
authors.lastname: Shokrgozar
authors.affiliation: Department of Molecular Biology, Pasteur Institute of Iran, Tehran, Iran.
authors.forename: Saeid
authors.initials: S
authors.lastname: Bouzari
authors.affiliation: Department of Recombinant Biopharmaceutical Production, Research and Production Complex, Pasteur Institute of Iran, Karaj, Iran.
authors.forename: Mina
authors.initials: M
authors.lastname: Sepahi
keywords: 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide assay; Fourier transform infrared spectroscopy; human basic fibroblast growth factor; polyethylene glycol methyl ether maleimide; stability