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1、生化工程第三章 固定化酶反应动力学ImmobilizedEnzymeSystemsDefinitionTherestrictionofenzymemobilityinafixedspaceisknownasenzymeimmobilization.Ingeneral,immobilizedenzymesareenzymesthatareattachedto,orentrappedwithin,amacro-scopicsupportmatrixsothattheresultingcatalystcanbereused
2、.TwooppositeconceptImmobilizedenzymeFreeenzyme§3.1AdvantagesofImmobilizedEnzymesAdvantages:Enzymereutilization:catalystreuse;Eliminationofenzymerecoveryandpurificationprocesses:productpurity,whileeffluenthandlingproblems;Provideabetterenvironmentforenzymeac
3、tivity;Disadvantages:Increasethediffusionresistance,sodecreasesthereactionrate.§3.2ApplicationsofImmobilizedEnzymesImmobilizedenzymeareemployedinmanyfields.Analyticaldevices:Forexample:inimmobilizedenzymeelectrodesforthedetectionofvariouschemicalsubstances.Asca
4、talystinindustrialprocesses:Among2000typesofenzymesfound,only50~60havebeenappliedinindustry,mostofwhichareextracellularenzymes.§3.3MethodsofImmobilizationImmobilizedSolubleEnzymesMembrane-EntrappedBetweenMacroscopicMembranesMicro-EncapsulatedCovalently-BoundToS
5、upportToEnzymeEntrappedBoundAdsorbed(PhysicalorIonic)Matrix-EntrappedEntrapment:Thephysicalenclosureofenzymesinasmallspace.Ploymericmaterials:Ca-alginate,agar,ĸ-carrageenin,polyacrylamide,collagen;Solidmatrices:activatedcarbon,porousceramic,diatomaceousearth.Ma
6、trixentrapmentMatricesusedforenzymeimmobilizationareusually:Whenimmobilizedinapolymermatrix,enzymesolutionismixedwithpolymersolutionbeforepolymerizationtakesplace.MembraneentrapmentMembrane:nylon,cellulose,polysulfone,polyacrylate.Inallcases,asemi-permeablememb
7、raneisusedtoretainhigh-MWcompounds(enzyme)whileallowingsmall-MWcompounds(substratesorproducts)accesstotheenzyme.Inthistechnique,microscopichollowspheresareformed.Thespherescontaintheenzymesolution,whilethesphereisenclosedwithaporousmembrane.Microencapsulation:a
8、specialformofmem-braneentrapment.Problems:Leakageofenzymesintosolution:Considerablediffusionalresistanceemerges:Reducingtheparticlesizeofthematricesand/orcapsules;Reductiono
