title: Immobilisation of a hydroperoxide lyase and comparative enzymological studies of the immobilised enzyme with membrane-bound enzyme.
abstract: BACKGROUND
  Hydroperoxide lyase is the key enzyme in lipoxygenase pathway producing green-note flavours and has potential value for the flavour additive industry. So far, only a low yield of green-note flavours produced by hydroperoxide lyase has been achieved, primarily because of its instability. The aim of this study was to stabilise hydroperoxide lyase from Amaranthus tricolor leaves by immobilisation and investigate the characteristics of immobilised enzyme in comparison with free and native membrane-bound enzyme.
  
  
  RESULTS
  A maximum activity of 2.85±0.1 U g(-1) (wet) ceramic hydroxyapatite and a yield of 80% were obtained under optimised coupling conditions. The optimal reaction pH was 6.0, 6.0 and 7.5 for free, membrane-bound and immobilised enzyme respectively, while the optimal reaction temperature was 30, 35 and 35 °C respectively. Thermal and operational stability of immobilised enzyme were substantially enhanced. However, a higher substrate diffusion resistance was imposed after immobilisation, as evidenced by the Km value of immobilised enzyme being higher than that of free and membrane-bound enzyme.
  
  
  CONCLUSIONS
  Ceramic hydroxyapatite was a candidate for the immobilisation of hydroperoxide lyase from A. tricolor leaves. The stability of hydroperoxide lyase was substantially improved after immobilisation on this substrate.
authors.affiliation: State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, China; School of Food Science and Technology, Jiangnan University, Wuxi, 214122, China.
authors.forename: Qingqing
authors.initials: Q
authors.lastname: Liu
authors.forename: Xiangzhen
authors.initials: X
authors.lastname: Kong
authors.forename: Caimeng
authors.initials: C
authors.lastname: Zhang
authors.forename: Yeming
authors.initials: Y
authors.lastname: Chen
authors.forename: Yufei
authors.initials: Y
authors.lastname: Hua
mesh_terms: D000446:Aldehyde-Lyases / Q000737:chemistry / Q000378:metabolism*; D002462:Cell Membrane / Q000201:enzymology*; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry / Q000378:metabolism*; D004800:Enzymes, Immobilized; D006863:Hydrogen-Ion Concentration; D007700:Kinetics
chemical_list: D004800:Enzymes, Immobilized; D003577:Cytochrome P-450 Enzyme System; D000446:Aldehyde-Lyases; C054540:hydroperoxide lyase