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时间:2020-03-06
《为什么纯化酶 Why Purify Enzymes by Arthur Kornberg.pdf》由会员上传分享,免费在线阅读,更多相关内容在工程资料-天天文库。
1、CHAPTERONEWhyPurifyEnzymes?wArthurKornberg‘‘Don’twastecleanthinkingondirtyenzymes’’isanadmonitionofEfraimRacker’swhichisatthecoreofenzymologyandgoodchemicalpractice.Itsimplysaysthatdetailedstudiesofhowanenzymecatalyzestheconversionofonesubstancetoanotherisgenerallyawasteoftime
2、untiltheenzymehasbeenpurifiedawayfromtheotherenzymesandsubstancesthatmakeupacrudecellextract.Themixtureofthousandsofdifferentenzymesreleasedfromadisruptedliver,yeast,orbacterialcelllikelycontainsseveralthatdirectotherrearrangementofthestartingmaterialandtheproductoftheparticul
3、arenzyme’saction.OnlywhenwehavepurifiedtheenzymetothepointthatnootherenzymescanbedetectedcanwefellassuredthatasingletypeofenzymemoleculedirectstheconversionofsubstanceAtosubstanceB,anddoesnothingmore.Onlythencanwelearnhowtheenzymedoesitswork.Therewardsforthelaborofpurifyingane
4、nzymewerelaidoutinaseriesofinspirationalpapersbyOttoWarburginthe1930s.FromhislaboratoryinBerlin-Dahlemcamethedisciplineandmanyofthemethodsofpurifyingenzymesandwiththosetheclarificationofkeyreactionsandvitaminfunc-tionsinrespirationandthefermentationofglucose.Warburg’scontribut
5、ionsstrengthenedtheclassicapproachtoenzymologyinauguratedwithEduardBu¨chner’saccidentaldiscovery,attheturnofthiscentury,ofcell-freeconversionofsucrosetoethanol.Onetracksthemolecularbasisofcellularfunction—alcoholicfermentationinyeast,glycolysisinmuscle,lumines-cenceinafly,orth
6、ereplicationofDNA—byfirstobservingthephenome-noninacell-freesystem.Thenoneisolatestheresponsibleenzyme(orenzymes)byfractionationofthecellextractandpurifiesittohomogene-ity.Thenonehopestolearnenoughaboutthestructureoftheenzymetoexplainhowitperformsitscatalyticfunctions,responds
7、toregulatorysignals,andisassociatedwithotherenzymesandstructuresinthecell.Byareverseapproach,callitneoclassical,especiallypopularinrecentdecades,onefirstobtainsastructureandthenlooksforitsfunction.Theproteinispreferablysmallandstable,andhasbeenamplifiedbycloningoriscommerciall
8、yavailable.Byintensivestudyoftheproteinandhomologousproteins,
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