title: Optimized condition for enhanced soluble-expression of recombinant mutant anabaena variabilis phenylalanine ammonia lyase.
abstract: OBJECTIVE
  Recently discovered Anabaena variabilis phenylalanine ammonia lyase (AvPAL) proved to be a good candidate for enzyme replacement therapy of phenylketonuria. Outstanding stability properties of a mutant version of this enzyme, produced already in our laboratory, have led us to the idea of culture conditions optimization for soluble expression of this therapeutically valuable enzyme in E. coli.
  
  
  METHODS
  In the present study, the gene encoding mutant version of AvPAL was cloned into the pET28a expression vector. Different concentrations of IPTG, induction period, growth temperature, shaking speed, as well as different types of culture media were examined with respect to the amount of recombinant protein produced and specific activity of the enzyme.
  
  
  RESULTS
  Based upon our findings, maximum amount of active mutant enzyme was attained by addition of 0.5 mM IPTG at 150 rpm to the TB culture media. The yield of active enzyme at cluture tempreature of 25 °C and induction period of 18 hour was the highest.
  
  
  CONCLUSIONS
  The results of this study indicated that the yield of mutant AvPAL production in E. coli can be affected mainly by culture temperature and inducer concentration.
authors.affiliation: Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz, Iran. ; Department of Medical Biotechnology, Faculty of Advanced Medical Sciences /Students Research Committee, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Hossein
authors.initials: H
authors.lastname: Zarei Jaliani
authors.affiliation: Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz, Iran. ; Biotechnology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Safar
authors.initials: S
authors.lastname: Farajnia
authors.affiliation: Biotechnology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Yaghoub
authors.initials: Y
authors.lastname: Safdari
authors.affiliation: Department of Agronomy and Plant Breeding, Faculty of Agriculture, University of Tabriz, Tabriz, Iran.
authors.forename: Seyyed Abolghasem
authors.initials: SA
authors.lastname: Mohammadi
authors.affiliation: Research Institute for Fundamental Sciences (RIFS), University of Tabriz, Tabriz, Iran.
authors.forename: Abolfazl
authors.initials: A
authors.lastname: Barzegar
authors.affiliation: Department of Antigen and Antibody Engineering Research, Monoclonal Antibody Research Center (MARC), Avicenna Research Institute (ARI), Tehran, Iran.
authors.forename: Saeed
authors.initials: S
authors.lastname: Talebi
keywords: Optimization; Phenylalanine ammonia lyase; Soluble expression; Specific activity
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