title: Acetylcholinesterase immobilization and characterization, and comparison of the activity of the porous silicon-immobilized enzyme with its free counterpart.
abstract: A successful prescription is presented for acetylcholinesterase physically adsorbed on to a mesoporous silicon surface, with a promising hydrolytic response towards acetylthiocholine iodide. The catalytic behaviour of the immobilized enzyme was assessed by spectrophotometric bioassay using neostigmine methyl sulfate as a standard acetycholinesterase inhibitor. The surface modification was studied through field emission SEM, Fourier transform IR spectroscopy, energy-dispersive X-ray spectroscopy, cathode luminescence and X-ray photoelectron spectroscopy analysis, photoluminescence measurement and spectrophotometric bioassay. The porous silicon-immobilized enzyme not only yielded greater enzyme stability, but also significantly improved the native photoluminescence at room temperature of the bare porous silicon architecture. The results indicated the promising catalytic behaviour of immobilized enzyme compared with that of its free counterpart, with a greater stability, and that it aided reusability and easy separation from the reaction mixture. The porous silicon-immobilized enzyme was found to retain 50% of its activity, promising thermal stability up to 90°C, reusability for up to three cycles, pH stability over a broad pH of 4-9 and a shelf-life of 44 days, with an optimal hydrolytic response towards acetylthiocholine iodide at variable drug concentrations. On the basis of these findings, it was believed that the porous silicon-immobilized enzyme could be exploited as a reusable biocatalyst and for screening of acetylcholinesterase inhibitors from crude plant extracts and synthesized organic compounds. Moreover, the immobilized enzyme could offer a great deal as a viable biocatalyst in bioprocessing for the chemical and pharmaceutical industries, and bioremediation to enhance productivity and robustness.
authors.affiliation: Department of Chemistry, Kongju National University, Gongju, Chungnam 314-701, Republic of Korea.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Saleem
authors.affiliation: Department of Biology, Kongju National University, Gongju, Chungnam 314-701, Republic of Korea Department of Biochemistry and Biotechnology, the Islamia University of Bahawalpur, Pakistan.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Rafiq
authors.affiliation: Department of Biology, Kongju National University, Gongju, Chungnam 314-701, Republic of Korea.
authors.forename: Sung-Yum
authors.initials: SY
authors.lastname: Seo
authors.affiliation: Department of Chemistry, Kongju National University, Gongju, Chungnam 314-701, Republic of Korea khlee@kongju.ac.kr.
authors.forename: Ki Hwan
authors.initials: KH
authors.lastname: Lee
mesh_terms: D000110:Acetylcholinesterase / Q000737:chemistry*; D004795:Enzyme Stability; D004800:Enzymes, Immobilized / Q000737:chemistry; D006358:Hot Temperature; D006801:Humans; D006863:Hydrogen-Ion Concentration; D016062:Porosity; D012825:Silicon / Q000737:chemistry*
chemical_list: D004800:Enzymes, Immobilized; D000110:Acetylcholinesterase; D012825:Silicon
keywords: acetylcholinesterase; biocatalyst; hydrolysis; immobilization; mesoporous; physical adsorption
references.citation: Biotechnol Lett. 2009 Nov;31(11):1639-50
references.pmid: 19590826
references.citation: ACS Appl Mater Interfaces. 2014 Aug 13;6(15):12012-21
references.pmid: 25032481
references.citation: Biomacromolecules. 2013 Aug 12;14(8):2433-62
references.pmid: 23822160
references.citation: EMBO J. 2006 Jun 21;25(12):2746-56
references.pmid: 16763558
references.citation: Exp Eye Res. 2014 Dec;129:74-82
references.pmid: 25446320
references.citation: Molecules. 2014;19(9):14139-94
references.pmid: 25207718
references.citation: Angew Chem Int Ed Engl. 2014 Sep 8;53(37):9822-6
references.pmid: 25044650
references.citation: Molecules. 2014;19(7):8995-9018
references.pmid: 24979403
references.citation: Chem Soc Rev. 2013 Aug 7;42(15):6290-307
references.pmid: 23059445
references.citation: Bioconjug Chem. 2014 Jul 16;25(7):1192-7
references.pmid: 24949894
references.citation: Nanoscale. 2012 Jan 21;4(2):414-6
references.pmid: 22095140
references.citation: Biomaterials. 2015 Jan;39:249-59
references.pmid: 25468375
references.citation: Eur J Pharmacol. 2004 Feb 6;485(1-3):299-305
references.pmid: 14757154
references.citation: Trends Biotechnol. 2008 Oct;26(10):566-72
references.pmid: 18757108
references.citation: Biotechnol Adv. 2015 Sep-Oct;33(5):435-56
references.pmid: 25777494
references.citation: Mol Neurobiol. 1994 Aug-Dec;9(1-3):93-106
references.pmid: 7888109
references.citation: Bioconjug Chem. 2014 Jul 16;25(7):1282-9
references.pmid: 24892699
references.citation: Anal Chem. 2004 Dec 1;76(23):6915-20
references.pmid: 15571341
references.citation: Carbohydr Polym. 2014 Sep 22;110:238-52
references.pmid: 24906752
references.citation: Chem Commun (Camb). 2014 May 21;50(39):4993-6
references.pmid: 24504122
references.citation: ACS Med Chem Lett. 2010 May 10;1(4):145-9
references.pmid: 24900188
references.citation: Biosens Bioelectron. 2010 Jan 15;25(5):1001-7
references.pmid: 19833501
references.citation: Enzyme Microb Technol. 2011 Feb 8;48(2):107-22
references.pmid: 22112819
references.citation: Trends Biotechnol. 1999 Aug;17(8):326-35
references.pmid: 10407405
references.citation: Biochem Pharmacol. 1961 Jul;7:88-95
references.pmid: 13726518
references.citation: Mol Pharm. 2014 Aug 4;11(8):2876-86
references.pmid: 24977922