Organic Synthesis with Enzymes in Non-Aqueous Media

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1、PartOneBiocatalysisinNeatOrganicSolvents–Fundamentals31FundamentalsofBiocatalysisinNeatOrganicSolventsPatrickAdlercreutz1.1IntroductionItiswellestablishedthatenzymescanexpresscatalyticactivityinpredominantlyorganicmedia[1–8].Insomecasesthereportedcatalyticactivitiesinorganicmedia

2、areseveralordersofmagnitudelowerthanthoseinaqueoussolution.However,bycarefulselectionofthetypeofenzymepreparationtouseandthereactionconditions,itisoftenpossibletoachievecatalyticactivitiesinthesameorderofmagnitudeasinwater.Typesofenzymeformulationsforcatalysisinorganicsolventsare

3、treatedinaseparatechapter,whilethischapterislargelyconcernedwithreactionconditionsforenzymaticcatalysisinorganicmedia.Themostimportantpointstoconsiderarethesolvent,thewatercontent,andenzymeionizationeffects(correspondingtopHeffectsinaqueousmedia).1.2EffectsofWateronBiocatalyticRe

4、actionsThisbookconcernstheuseofenzymesinnon-aqueousmedia,whichmeansthatthemajorpartofthemediumsurroundingtheenzymeisnon-aqueous.However,itisextremelydifficulttoremovewatercompletelyfromenzymes.Evenafterextensivedrying,afewwatermoleculesremaintightlyboundtotheenzyme[6],andinmostcas

5、esenzymeactivitycanbeincreasedconsiderablybysupplyinganoptimalamountofwatertothesystem.Itisthusveryimportanttocontroltheamountofwaterinthereactionmixturesinaproperway.1.2.1QuantificationofWaterinLow-WaterSystemsThemoststraightforwardwaytoquantifytheamountofwaterinareaction−1mixtur

6、eistousethewaterconcentration(inmolLor%byweightorvolume).However,thepropertiesoftheenzyme(catalyticactivity,etc.)aremuchmoreOrganicSynthesiswithEnzymesinNon-AqueousMedia.EditedbyGiacomoCarreaandSergioRivaCopyright©2008WILEY-VCHVerlagGmbH&Co.KGaA,WeinheimISBN:978-3-527-31846-941Fu

7、ndamentalsofBiocatalysisinNeatOrganicSolventsinfluencedbytheamountofwaterboundtotheenzymethanbythetotalwaterconcentration[9].Unfortunately,itisdifficulttomeasuretheamountofwaterboundtotheenzymedirectly.Ontheotherhand,ithasbeenfoundthattheamountofwaterboundtotheenzymeislargelyinfluen

8、cedbythethermodynamicwateractivity(relat