资源描述：
《Did nature also choose arsenic.pdf》由会员上传分享，免费在线阅读，更多相关内容在学术论文-天天文库。
1、1Didnaturealsochoosearsenic?1*21,3FelisaWolfe-Simon,PaulC.W.Davies,andArielD.Anbar1MetallomicsLaboratory,DepartmentofChemistryandBiochemistry,ArizonaState2University,Tempe,AZ85287,USA;BEYOND:CenterforFundamentalConceptsin3Science,ArizonaStateUniversity,Tempe,AZ85287,USA;SchoolofE
2、arthandSpaceExploration,ArizonaStateUniversity,Tempe,AZ85287,USAOnesentencesummary:Lifeaswedonotknowit:arsenicbasedbiology.NaturePrecedings:hdl:10101/npre.2008.1482.1:Posted2Jan2008*Presentaddress:DepartmentofEarthandPlanetarySciences,HarvardUniversity,20OxfordSt,Cambridge,MA0213
3、8,USA2-Allknownliferequiresphosphorus(P)intheformofinorganicphosphate(PO4or1Pi)andphosphate-containingorganicmolecules.Piservesasthebackboneofthenucleicacidsthatconstitutegeneticmaterialandasthemajorrepositoryofchemicalenergyformetabolisminpolyphosphatebonds.Arsenic(As)liesdirect
4、lybelowPontheperiodictableandsothetwoelementssharemanychemicalproperties,althoughtheirchemistriesaresufficientlydissimilarthatAscannotdirectlyreplacePinmodernbiochemistry.ArsenicistoxicpreciselybecauseAsandParesimilarenoughthatorganismsattemptthissubstitution.Wehypothesizethatanc
5、ientbiochemicalsystems,analogoustobutdistinctfromthoseknowntoday,couldhaveutilizedarsenateintheequivalentbiologicalroleasphosphate.Organismsutilizingsuch"weirdlife"biochemicalpathwaysmayhavesupporteda“shadowbiosphere”atthetimeoftheoriginandearlyevolutionoflifeonEarthoronotherplan
6、ets.SuchorganismsmayevenpersistonEarthtoday,undetected,inunusualniches.NaturePrecedings:hdl:10101/npre.2008.1482.1:Posted2Jan20083PranksjustbehindH,O,CandNinaquantitativelistofthemostimportantelementsinbiology.However,Pisusuallylessavailabletolifethantheseotherelements,particular
7、lyintheoceans.HandOareavailableinanyaqueoussolution,whileCandNcanbefoundingaseouscompoundsthatarereadilydistributedthroughtheatmosphereandcanbeconvertedtohighlysolublechemicalforms.Incontrast,whilePis2arelativelycommonelementintheEarth’scrust(0.1%byweight),thereisnogasphasePcompo
8、undanalogoustoCO2,CH4,N2orNH3,andcommonp
