title: Expression of a fungal manganese peroxidase in Escherichia coli: a comparison between the soluble and refolded enzymes.
abstract: BACKGROUND
  Manganese peroxidase (MnP) from Irpex lacteus F17 has been shown to have a strong ability to degrade recalcitrant aromatic pollutants. In this study, a recombinant MnP from I. lacteus F17 was expressed in Escherichia coli Rosetta (DE3) in the form of inclusion bodies, which were refolded to achieve an active enzyme. Further, we optimized the in vitro refolding conditions to increase the recovery yield of the recombinant protein production. Additionally, we attempted to express recombinant MnP in soluble form in E. coli, and compared its activity with that of refolded MnP.
  
  
  RESULTS
  Refolded MnP was obtained by optimizing the in vitro refolding conditions, and soluble MnP was produced in the presence of four additives, TritonX-100, Tween-80, ethanol, and glycerol, through incubation at 16 °C. Hemin and Ca2+supplementation was crucial for the activity of the recombinant protein. Compared with refolded MnP, soluble MnP showed low catalytic efficiencies for Mn2+and H2O2substrates, but the two enzymes had an identical, broad range substrate specificity, and the ability to decolorize azo dyes. Furthermore, their enzymatic spectral characteristics were analysed by circular dichroism (CD), electronic absorption spectrum (UV-VIS), fluorescence and Raman spectra, indicating the differences in protein conformation between soluble and refolded MnP. Subsequently, size exclusion chromatography (SEC) and dynamic light scattering (DLS) analyses demonstrated that refolded MnP was a good monomer in solution, while soluble MnP predominantly existed in the oligomeric status.
  
  
  CONCLUSIONS
  Our results showed that two forms of recombinant MnP could be expressed in E. coli by varying the culture conditions during protein expression.
authors.affiliation: School of Life Science, Anhui University, 111 Jiulong Road, Economic and Technology Development Zone, Hefei, Anhui, 230601, People's Republic of China.
authors.forename: Nan
authors.initials: N
authors.lastname: Wang
authors.affiliation: School of Life Science, Anhui University, 111 Jiulong Road, Economic and Technology Development Zone, Hefei, Anhui, 230601, People's Republic of China.
authors.forename: Kai
authors.initials: K
authors.lastname: Ren
authors.affiliation: School of Life Science, Anhui University, 111 Jiulong Road, Economic and Technology Development Zone, Hefei, Anhui, 230601, People's Republic of China. ahdxjiarong@126.com.
authors.forename: Rong
authors.initials: R
authors.lastname: Jia
authors.affiliation: School of Life Science, Anhui University, 111 Jiulong Road, Economic and Technology Development Zone, Hefei, Anhui, 230601, People's Republic of China.
authors.forename: Wenting
authors.initials: W
authors.lastname: Chen
authors.affiliation: School of Life Science, Anhui University, 111 Jiulong Road, Economic and Technology Development Zone, Hefei, Anhui, 230601, People's Republic of China.
authors.forename: Ruirui
authors.initials: R
authors.lastname: Sun
mesh_terms: D001487:Basidiomycota / Q000201:enzymology* / Q000235:genetics*; D004789:Enzyme Activation; D004795:Enzyme Stability; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics*; D010544:Peroxidases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011487:Protein Conformation; D058849:Protein Refolding; D012995:Solubility
chemical_list: D010544:Peroxidases; C051129:manganese peroxidase
keywords: Escherichia coli; Inclusion bodies; Kinetic properties; Manganese peroxidase; Protein expression; Protein refolding; Spectral characteristics