title: Covalent binding of hyper-activated Rhizomucor miehei lipase (RML) on hetero-functionalized siliceous supports.
abstract: Physical adsorption onto hydrophobic supports has proven to be an effective way to improve the activity of lipases. Covalent binding, on the other hand, enhances the active lifetime of the immobilized biocatalysts. To combine the benefits of adsorption and covalent binding, immobilization of RML on new hetero-functional supports are reported. For this, chemical modification of silica and silica mesoporous nanoparticles was performed by the simultaneous use of two coupling linkers; Octyltriethoxysilane (OTES) for hydrophobic interaction and glycidoxypropyltrimethoxylsilane (GPTMS) for covalent linkage of RML. Altering the GPTMS/OTES ratio makes possible to have different amount of octyl and epoxy groups on the supports. The results showed that immobilization of RML on octyl-functionalized supports produces specific activity almost 1.5-2 folds greater than the specific activity of the free enzyme. The observed hyper-activation decreased with increasing epoxy groups on the supports confirming the enhancement of covalent nature of the attachment. Leaching experiment was also confirmed positive effect of the presence of epoxy groups on the supports. Regarding the specific activity of the immobilized preparations and desorption percentages of RML from each support, the most suitable carrier obtains from the functionalization of the supports in presence of GPTMS and OTES in the ratio of 1:1.
authors.affiliation: Department of Chemistry, University of Zanjan, Zanjan, Iran.
authors.forename: Maryam
authors.initials: M
authors.lastname: Garmroodi
authors.affiliation: Bioprocess Engineering Department, Institute of Industrial and Environmental Biotechnology, National Institute of Genetic Engineering and Biotechnology (NIGEB), P.O. Box 14965/161, Tehran, Iran. Electronic address: M.mohammadi@nigeb.ac.ir.
authors.forename: Mehdi
authors.initials: M
authors.lastname: Mohammadi
authors.affiliation: Department of Chemistry, University of Zanjan, Zanjan, Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Ramazani
authors.affiliation: Bioprocess Engineering Department, Institute of Industrial and Environmental Biotechnology, National Institute of Genetic Engineering and Biotechnology (NIGEB), P.O. Box 14965/161, Tehran, Iran.
authors.forename: Maryam
authors.initials: M
authors.lastname: Ashjari
authors.affiliation: Department of Environmental Health Engineering, Zanjan University of Medical Sciences, Zanjan, Iran.
authors.forename: Javad
authors.initials: J
authors.lastname: Mohammadi
authors.affiliation: Department of Chemistry, Amirkabir University of Technology (Tehran Polytechnic), Tehran, Iran.
authors.forename: Behrouz
authors.initials: B
authors.lastname: Sabour
authors.affiliation: Nanobiotechnology Research Center, Avicenna Research Institute, ACECR, Tehran, Iran. Electronic address: m.yousefi@avicenna.ac.ir.
authors.forename: Maryam
authors.initials: M
authors.lastname: Yousefi
mesh_terms: D000327:Adsorption; D004789:Enzyme Activation; D004800:Enzymes, Immobilized / Q000737:chemistry* / Q000378:metabolism; D057927:Hydrophobic and Hydrophilic Interactions; D008049:Lipase / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D020103:Rhizomucor / Q000201:enzymology*; D012821:Silanes / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry*
chemical_list: D004800:Enzymes, Immobilized; D012821:Silanes; D012822:Silicon Dioxide; D008049:Lipase
keywords: Covalent immobilization; Physical adsorption; Rhizomucor miehei lipase; SBA-15; Silica gel