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Study Of Lip2Lipase Immobilied On Carbon Nanotubes By Molecular Dynamics Simulation

Posted on:2013-11-18Degree:MasterType:Thesis
Country:ChinaCandidate:X C SunFull Text:PDF
GTID:2231330374457521Subject:Chemical Engineering and Technology
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Lip2lipase shows high stereo-selectivity and has been widely used asbiocatalysts for numerous biotechnological applications. The experimentalresults show significantly enhanced activity of the Lip2lipase immobilized oncarbon nanotubes(CNTs) in chiral resolution of (r,s)-1-phenylethanol. In thiswork, molecular dynamic simulation had been performed to elucidate theactivation mechanism of the immobilized lipase.The NZ atom on218LYS of Lip2lipase was connected with the carbonatom of carbon nanotube through covalent bond to form the immobilizedenzyme-case1. To simulate the adsorption of the lipase on the SCNT, weselected6orientations. The orientations were selected by considering thedistribution of hydrophobic residues on the surface of the protein as well as thesteric hindrance for the adsorption. The most favorable orientation for Lip2lipases adsorbing on carbon nanotube was identified, and the system isdesignated as case2. The Lip2lipases of all systems (case1, case2, free lipase) are preprocessed on protons state and the complement of residues.The mechanism of activity enhancement of immobilized lipase in heptaneorganic solvent was investigated based on molecular dynamics simulationresults. The analysis is carried from the following aspects-residues incontacting with the SCNT, lid opening, minimum distances between amino acidresidues, essential dynamic (ED) analysis, salt bridge and hydrongen bondinginteractions. The results indicate that the Lip2lipase interacts with the SCNT ata local site, the effects of that interaction are propagated to a remote lidsubdomain. The chain of events initiated by the interaction provides the basisfor a fundamental understanding of the lid opening mechanism. We identify thestructural path followed by cooperative interactions that originate at theinteraction site. Salt bridge and hydrogen bonding interactions, whichcontribute to the propagation of interaction effects to distal regions, are alsoidentified.For case1, case2, and free lipase, the substrates (r)-1-phenethyl alcoholwere added and molecular dynamics simulations were performed. The resultsshow the lid exhibits open conformation in the presence of the substrate and thehydrogen bonds, which are vital for the catalysis activity of lipases, at thecatalytic sites are preserved well.
Keywords/Search Tags:Lip2lipase, carbon nanotube, immobilized lipase, moleculardynamics simulation
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