characterization of a hyperthermostable

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1、ApplMicrobiolBiotechnol(2007)75:367–376DOI10.1007/s00253-006-0834-3BIOTECHNOLOGICALLYRELEVANTENZYMESANDPROTEINSCharacterizationofahyperthermostableFe-superoxidedismutasefromhotspringYong-ZhiHe&Ke-QiangFan&Cui-JuanJia&Zhi-JunWang&Wu-BinPan&LiHuang&Ke-QianYang&Zhi-YangDongReceived:30O

2、ctober2006/Revised:25December2006/Accepted:28December2006/Publishedonline:30January2007#Springer-Verlag2007AbstractAnewgeneencodingathermostableFe-tion-independentapproaches(extractingDNAdirectlysuperoxidedismutase(tcSOD)wasidentifiedfromafromenvironmentalsamplesandconstructingmetag

3、e-metagenomiclibrarypreparedfromahotspringsample.nomiclibraries)havebeendevelopedtostudytheseTheopenreadingframeoftcSODencodeda211aminolargelyuntappedorganismsandtheirfunctions.Inrecentacidprotein.Therecombinantproteinwasoverexpressedyears,anincreasingnumberofnewgenesencodinginEsche

4、richiacoliandconfirmedtobeaFe–SODwithapotentiallyusefulenzymeshavebeenidentifiedfromspecificactivityof1,890U/mgusingthepyrogallolunculturedmicrobesbycultivation-independentways.method.Theenzymewashighlystableat80°CandTheseincludechitinasefromuncultivatedmarinebacteriaretained50%acti

5、vityafterheattreatmentat95°Cfor2h.(Cottrelletal.1999),lipolyticenzymesfromsoilsamplesItshowedstrikingstabilityacrossawidepHspanfrom4(Henneetal.2000),andthermostableesterasefromhotto11.Thenativeformoftheenzymewasdeterminedasaspringandmudholesamples(Rheeetal.2005).Manyhomotetramerbyan

6、alyticalultracentrifugationandgradi-methodshavebeendevelopedtoscreenametagenomic2+entnativepolyacrylamidegelelectrophoresis.Fewaslibraryforgenesofinterest.ScreeningmaybebasedonfoundtobeimportanttoSODactivityandtothestabilityhybridizationwithaknownprobe,orasimpleenzymeoftcSODdimer.Co

7、mparativemodelinganalysesofassay.However,thesemethodsareofoften-limitedusetcSODtetramerindicatethatitshighthermostabilityisduetotechnicalproblemsordependenceonfortuitousmainlyduetothepresenceofalargenumberofexpressionoffunctionalproteins.High-throughoutendintersubunitionpairsandhydr

8、ogenbondsandtoasequ