title: Preparation and characterization of a highly stable phenoxazinone synthase nanogel.
abstract: BACKGROUND
  Phenoxazinone synthase (PHS) is a laccase-like multicopper oxidase originating from Streptomyces with great industrial application potential. In this paper, we prepared the PHS nanogel retaining 82 % of its initial activity by aqueous in situ polymerization at pH 9.3.
  
  
  RESULTS
  The average diameter of the PHS nanogel was 50.8 nm based on dynamic light scattering (DLS) analysis. Fluorescence analysis indicated the impressive preservation of the enzyme molecular structure upon modification. The PHS nanogel exhibited the most activity at pH 4.0-4.5 and 50 °C while the corresponding values were pH 4.5 and 40 °C for the native PHS. The K m and V max of the PHS nanogel were found to be 0.052 mM and 0.018 mM/min, whereas those of the native PHS were 0.077 mM and 0.021 mM/min, respectively. In addition, the PHS nanogel possessed higher thermal and storage stability and solvent tolerance compared with the native one. The half-life of the PHS nanogel was 1.71 h and multiplied around ninefold compared to 0.19 h for the native one.
  
  
  CONCLUSIONS
  In summary, the PHS nanogel could be a promising biocatalyst in industry.
authors.affiliation: College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, 211800 China.
authors.forename: Honghua
authors.initials: H
authors.lastname: Jia
authors.affiliation: College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, 211800 China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Gao
authors.affiliation: College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, 211800 China.
authors.forename: Yingying
authors.initials: Y
authors.lastname: Ma
authors.affiliation: College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, 211800 China.
authors.forename: Chao
authors.initials: C
authors.lastname: Zhong
authors.affiliation: College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, 211800 China.
authors.forename: Chunming
authors.initials: C
authors.lastname: Wang
authors.affiliation: College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, 211800 China.
authors.forename: Hua
authors.initials: H
authors.lastname: Zhou
authors.affiliation: College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, 211800 China.
authors.forename: Ping
authors.initials: P
authors.lastname: Wei
keywords: Laccase; Nanogel; Phenoxazinone synthase; Solvent resistance; Stability