title: Heat inactivation kinetics of Hypocrea orientalis β-glucosidase with enhanced thermal stability by glucose.
abstract: Thermal inactivation kinetics of Hypocrea orientalis β-glucosidase and effect of glucose on thermostability of the enzyme have been determined in this paper. Kinetic studies showed that the thermal inactivation was irreversible and first-order reaction. The microscopic rate constants for inactivation of free enzyme and substrate-enzyme complex were both determined, which suggested that substrates can protect β-glucosidase against thermal deactivation effectively. On the other hand, glucose was found to protect β-glucosidase from heat inactivation to remain almost whole activity below 70°C at 20mM concentration, whereas the apparent inactivation rate of BG decreased to be 0.3×10(-3)s(-1) in the presence of 5mM glucose, smaller than that of sugar-free enzyme (1.91×10(-3)s(-1)). The intrinsic fluorescence spectra results showed that glucose also had stabilizing effect on the conformation of BG against thermal denaturation. Docking simulation depicted the interaction mode between glucose and active residues of the enzyme to produce stabilizing effect.
authors.affiliation: Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen 361005, China.
authors.forename: Xin-Qi
authors.initials: XQ
authors.lastname: Xu
authors.affiliation: Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen 361005, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Shi
authors.affiliation: Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen 361005, China.
authors.forename: Xiao-Bing
authors.initials: XB
authors.lastname: Wu
authors.affiliation: Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen 361005, China.
authors.forename: Xi-Lan
authors.initials: XL
authors.lastname: Zhan
authors.affiliation: State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361005, China. Electronic address: htzhou@xmu.edu.cn.
authors.forename: Han-Tao
authors.initials: HT
authors.lastname: Zhou
authors.affiliation: Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen 361005, China. Electronic address: chenqx@xmu.edu.cn.
authors.forename: Qing-Xi
authors.initials: QX
authors.lastname: Chen
mesh_terms: D001592:Benzyl Alcohols / Q000494:pharmacology; D002475:Cellobiose / Q000494:pharmacology; D004795:Enzyme Stability / Q000187:drug effects; D005947:Glucose / Q000494:pharmacology*; D005960:Glucosides / Q000494:pharmacology; D006358:Hot Temperature; D006868:Hydrolysis; D035901:Hypocrea / Q000187:drug effects / Q000201:enzymology*; D007700:Kinetics; D062105:Molecular Docking Simulation; D013050:Spectrometry, Fluorescence; D001617:beta-Glucosidase / Q000378:metabolism*
chemical_list: D001592:Benzyl Alcohols; D005960:Glucosides; D002475:Cellobiose; C005696:salicin; D001617:beta-Glucosidase; D005947:Glucose
keywords: Conformation stabilization; Glucose; Thermoinactivation kinetics; β-Glucosidase