title: Enhanced stability of catalase covalently immobilized on functionalized titania submicrospheres.
abstract: In this study, a novel approach combing the chelation and covalent binding was explored for facile and efficient enzyme immobilization. The unique capability of titania to chelate with catecholic derivatives at ambient conditions was utilized for titania surface functionalization. The functionalized titania was then used for enzyme immobilization. Titania submicrospheres (500-600 nm) were synthesized by a modified sol-gel method and functionalized with carboxylic acid groups through a facile chelation method by using 3-(3,4-dihydroxyphenyl) propionic acid as the chelating agent. Then, catalase (CAT) was covalently immobilized on these functionalized titania submicrospheres through 1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride/N-hydroxysuccinimide (EDC/NHS) coupling reaction. The immobilized CAT retained 65% of its free form activity with a loading capacity of 100-150 mg/g titania. The pH stability, thermostability, recycling stability and storage stability of the immobilized CAT were evaluated. A remarkable enhancement in enzyme stability was achieved. The immobilized CAT retained 90% and 76% of its initial activity after 10 and 16 successive cycles of decomposition of hydrogen peroxide, respectively. Both the Km and the Vmax values of the immobilized CAT (27.4 mM, 13.36 mM/min) were close to those of the free CAT (25.7 mM, 13.46 mM/min).
authors.affiliation: Key Laboratory for Green Chemical Technology, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Wu
authors.forename: Yanpeng
authors.initials: Y
authors.lastname: Liang
authors.forename: Jiafu
authors.initials: J
authors.lastname: Shi
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Wang
authors.forename: Dong
authors.initials: D
authors.lastname: Yang
authors.forename: Zhongyi
authors.initials: Z
authors.lastname: Jiang
mesh_terms: D000818:Animals; D002374:Catalase / Q000378:metabolism* / Q000648:ultrastructure; D002417:Cattle; D004795:Enzyme Stability / Q000187:drug effects; D004800:Enzymes, Immobilized / Q000378:metabolism* / Q000648:ultrastructure; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008863:Microspheres; D011489:Protein Denaturation / Q000187:drug effects; D059027:Recycling; D013052:Spectrometry, X-Ray Emission; D013696:Temperature; D014025:Titanium / Q000494:pharmacology*
chemical_list: D004800:Enzymes, Immobilized; C009495:titanium dioxide; D014025:Titanium; D002374:Catalase
keywords: Biocatalysis; Covalent binding; Immobilized enzyme; Kinetic parameters; Stability; Titania