title: Thermal inactivation of a recombinant lipoxygenase from Pseudomonas aeruginosa BBE in the absence and presence of additives.
abstract: BACKGROUND
  Bacterial lipoxygenase (EC 1.13.11.12, LOX) is an important enzyme used as a brightener and strengthening agent during breadmaking. In this study, thermal inactivation of a recombinant LOX of Pseudomonas aeruginosa BBE was characterized by kinetic and thermodynamic analysis in the absence and presence of additives.
  
  
  RESULTS
  As the heating temperature increased from 25 to 55 °C, the thermal inactivation rate (k) values for LOX without the additives ranged from 0.0407 to 0.2627 min(-1), while the half-life (t1/2) values were between 17.08 and 3.25 min. The activation energy (ΔE) values were increased with rise in heating temperatures from 13.26 to 108.9 kJ mol(-1) . Separate tests at 45 °C in the presence of additives (polyols, sugars and ions) at specific concentrations showed that xylitol (1 mol L(-1)) was the most effective stabilizer for recombinant LOX and increased the t1/2 value by 297%.
  
  
  CONCLUSIONS
  Recombinant LOX was sensitive to heat treatment, and addition of polyols, sugars and ions could enhance its thermal stability. Our findings may provide useful information for stabilizing emerging bacterial LOXs.
authors.affiliation: Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, 214122, Wuxi, China.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Xu
authors.forename: Song
authors.initials: S
authors.lastname: Liu
authors.forename: Xinyao
authors.initials: X
authors.lastname: Lu
authors.forename: Shengqi
authors.initials: S
authors.lastname: Rao
authors.forename: Zhen
authors.initials: Z
authors.lastname: Kang
authors.forename: Jianghua
authors.initials: J
authors.lastname: Li
authors.forename: Miao
authors.initials: M
authors.lastname: Wang
authors.forename: Jian
authors.initials: J
authors.lastname: Chen
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism; D001939:Bread; D003296:Cooking; D004032:Diet; D019422:Dietary Sucrose; D004795:Enzyme Stability; D005503:Food Additives; D006358:Hot Temperature; D006801:Humans; D007477:Ions; D007700:Kinetics; D008084:Lipoxygenase / Q000378:metabolism*; D011550:Pseudomonas aeruginosa / Q000201:enzymology*; D011994:Recombinant Proteins / Q000378:metabolism; D014993:Xylitol
chemical_list: D001426:Bacterial Proteins; D019422:Dietary Sucrose; D005503:Food Additives; D007477:Ions; D011994:Recombinant Proteins; D008084:Lipoxygenase; D014993:Xylitol
keywords: additive; bacterial lipoxygenase; kinetic; thermal inactivation; thermodynamics