title: Application of novel electrospun nanofibrous membranes with different modifications for immobilising glutamine synthetase.
abstract: BACKGROUND
  Theanine synthesis is of interest because of the physiological and pharmacological benefits of theanine. Glutamine synthetase (GS, EC 6.3.1.2) from Pseudomonas taetrolens can be used for theanine biosynthesis. In this study, GS was immobilised in polyvinyl alcohol electrospun nanofibres, and the properties of immobilised GS with different solidifying modifications were studied.
  
  
  RESULTS
  Electrospinning is a good method for enzyme immobilisation. When carbon nanotubes were used as an adsorbent, the activity retention of immobilised GS was 92.3%. With glutaraldehyde as a crosslinker, the enzyme activity retention was only 50.7%; however, by adding collagen or peptide to the electrospinning solution with glutaraldehyde, the activity retention could be improved to 85.9 or 59.6% respectively. Scanning electron micrographs showed that the modifiers induced morphological changes in the nanofibres. The optimum pH and temperature of immobilised GS also changed. In addition, the reusability and storage stability of immobilised GS with glutaraldehyde were much better than those of immobilised GS with carbon nanotubes.
  
  
  CONCLUSIONS
  A novel method has been established in this study for the immobilisation of GS in electrospun nanofibrous membranes. Carbon nanotubes and glutaraldehyde enhanced the immobilisation, while collagen or peptide inclusion could recover the activity loss caused by glutaraldehyde. The obtained immobilised enzyme achieved high reusability and storage stability.
authors.affiliation: School of Life Sciences and Technology, Tongji University, Shanghai 200092, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Liu
authors.forename: Ling
authors.initials: L
authors.lastname: Ge
authors.forename: Chenlu
authors.initials: C
authors.lastname: Zhang
authors.forename: Yusheng
authors.initials: Y
authors.lastname: Zhao
authors.forename: Ping
authors.initials: P
authors.lastname: Li
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D003094:Collagen / Q000737:chemistry / Q000648:ultrastructure; D003432:Cross-Linking Reagents / Q000737:chemistry; D055664:Electrochemical Techniques; D004795:Enzyme Stability; D004800:Enzymes, Immobilized / Q000737:chemistry / Q000378:metabolism*; D005503:Food Additives / Q000378:metabolism*; D005974:Glutamate-Ammonia Ligase / Q000737:chemistry / Q000378:metabolism*; D005971:Glutamates / Q000378:metabolism*; D005976:Glutaral / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D057139:Nanofibers / Q000737:chemistry* / Q000648:ultrastructure; D037742:Nanotubes, Carbon / Q000737:chemistry / Q000648:ultrastructure; D010455:Peptides / Q000737:chemistry; D011142:Polyvinyl Alcohol / Q000737:chemistry*; D011549:Pseudomonas / Q000201:enzymology; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature
chemical_list: D001426:Bacterial Proteins; D003432:Cross-Linking Reagents; D004800:Enzymes, Immobilized; D005503:Food Additives; D005971:Glutamates; D007202:Indicators and Reagents; D037742:Nanotubes, Carbon; D010455:Peptides; C026166:theanine; D011142:Polyvinyl Alcohol; D003094:Collagen; D005974:Glutamate-Ammonia Ligase; D005976:Glutaral