简介:ThebindingofCo(bpy)2dppz3+tocalfthymusDNAwasinvestigatedbyusingabsorptionandemissionspectroscopy,DNAmeltingtechniques,cyclicvoltammetry,viscosityandelectro-phoresismeasurements,wherebpyis2,2’-bipyridyl,dppzisdipyrido[3,2-o:2’,3’-c]phenazine.Thebindingcompoundshowsabsorptionhypochromicity,fluorescenceenhancement,andincreasingofDNAmeltingtemperatureandthespecificviscosity.CVmeasurementshowstheshiftsinoxidation-reductionpotentialandchangeinpeakcurrentwithadditionofDNA.ThecompoundisalsoshowntobemoreefficientphotosensitisersforstrandbreaksinplasmidDNA.
简介:DNAcondensationisanimportantprocessinmanyfieldsincludinglifesciences,polymerphysics,andappliedtechnology.Inthenucleus,DNAiscondensedintochromosomes.Inpolymerphysics,DNAistreatedasasemi-flexiblemoleculeandapolyelectrolyte.Manyagents,includingmulti-valentcations,surfactants,andneutralpoorsolvents,cancauseDNAcondensation,alsoreferredtoascoil–globuletransition.Moreover,DNAcondensationhasbeenusedforextractionandgenedeliveryinappliedtechnology.ManyphysicaltheorieshavebeenpresentedtoelucidatethemechanismunderlyingDNAcondensation,includingthecounterioncorrelationtheory,theelectrostaticzippertheory,andthehydrationforcetheory.Recentlyseveralsingle-moleculestudieshavefocusedonDNAcondensation,sheddingnewlightonoldconcepts.Inthisdocument,themulti-fieldconceptsandtheoriesrelatedtoDNAcondensationareintroducedandclarifiedaswellastheadvancesandconsiderationsofsingle-moleculeDNAcondensationexperimentsareintroduced.
简介:TheeffectofCdionsonsalmonspermDNAwasstudiedbymeansofcirculardichroism(CD),Ramanspectroscopy,X-rayphotoelectronspectroscopy(XPS)andfluorescencespectroscopy.TheCDspectralandfluorescentprobe-acriflavineresultsindicatethattheDNAunderwentaconformationchangeupontheadditionofCdions.XPSandRamanstudiesrevealthatthereexistedinteractionsbetweenCdionsandthephosphategroupsoftheDNA.Inaddition,anewbandappearedat803cm-1intheRamanspectra,whichcanbeattributedtocharacterizing"marker"bandofA-DNA.ItisconcludedthatCdionscanbecoordinatedbythephosphategroupsoftheDNAandinducetheconformationchangesoftheDNAfromB-DNAtoA-DNA.
简介:HydrolysisofDNAisanimportantenzymaticreaction,butitisexceedinglydifficulttomimicinthelaboratorybecauseofthestabilityofhydrolysisofDNA.Inthispaper,thecleavageactivityofcomplexesformedbetweenCu(Ⅱ)andfourdifferentaminoacidoraminoacidmethylesteronDNAisstudiedbygelelec-trophoresis.ItisfoundthatDNAcouldbecleavedbyCu(Ⅱ)-L-HisandCu(Ⅱ)-L-Hismethylestercomplexesandtheefficiencyofcleavageislargelydependentonthemetalion-to-ligandratio.FurtherexperimentsshowthatthecleavageofDNAmediatedbyCu(Ⅱ)-L-HiscomplexesoccursviaahydrolyticmechanismandtheactivechemicalspeciesthataffectsDNAcleavageisproposedtobeMI2H+andML2H22+.
简介:AdoublehelixmodelofchargetransportinDNAmoleculeisgivenandthetransmissionspectraoffourDNAsequencesareobtained.ThecalculatedresultsshowthatthetransmissioncharacteristicsofDNAarenotonlyrelatedtothelongitudinaltransportbutalsotothetransversetransportofmolecule.Theperiodicsequencewiththesamecompositionhasstrongerconductionability.Withtheincreasingofbasescomposition,theconductiveabilityreduces,buttheweightofθdirectionrisesinchargetransfer.
简介:Adetectionofanthracyclineantitumordrugdaunomycin(DNR)reactingwithDNAinsimulatemetabolisminvitrohasbeenmade.ItwasfoundthatDNRcouldreactwithDNAtoformDNR-DNAadducts.TheadductcompositionsofDNRwithfishspermDNAandthermallydenaturatedDNAweredetermined.TheequilibriumassociationconstantKofDNRwithfishspermDNAis1.98×10^5L/molandthatofDNRwithdenaturatedDNAis2.29×10^4L/mol.Semiquinonefreeradicals,metabolicproductsofDNR,candestroybothfishspermDNAanditsthermallydenaturatedDNA.ItisverifiedbyhyperchromiceffectincreaseobservedinUVspectrumandAFMexperiments.ThemechanismofDNAdegradationhasalsobeeninvestigated.Resultsobtainedallowonetoexplainthereasonofsideeffectofanthracyclinedrugandgivethewaytodepress,whichwereofclinicalsignificance.
简介:AvohammetricstudyoftheinteractionofneutralRed(NR)withDNAatagoldelectrodeinaphosphatebuffersolutionisdescribed.AfteraddingDNAinanNRsolution,thereductionpeakcurrentofNRdecreases.ThebindingmeehahismsofNRtoDNAindifferentpHrangesaredifferent.ThereductionpeakpotentialofNRinapH7.0phosphatebuffersolutioninthepresenceofDNAshiftspositively,indicatingthatthebindingofNRtoDNAisintercalationaction,butatpH=6.0thereductionpeakpotentialofNRshiftsnegatively,indicatingthatthebindingofNRtoDNAiselectrostaticaction.TheformedcomplexesareDNA-NRwhen[NR]/[DNA]<0.18andDNA-3NRwhen[NR]/[DNA]>0.35,respectively.
简介:Moleculardynamics(MD)simulationsareperformedtostudyadhesionandpeelingofashortfragmentofsinglestrandDNA(ssDNA)moleculefromagraphitesurface.Thecriticalpeel-offforceisfoundtodependonboththepeelingangleandtheelasticityofssDNA.FortheshortssDNAstrandunderinvestigation,weshowthatthesimulationresultscanbeexplainedbyacontinuummodelofanadhesiveelasticbandonsubstrate.Theanalysissuggeststhatitisoftenthepeakvalue,ratherthanthemeanvalue,ofadhesionenergywhichdeterminesthepeelingofananoscalematerial.
简介:MtDNAwassuccessfullyextractedfromtenindividualbones(femurs)inthetombsofancientJushiinTurfanbasin,datedbacktotheyearabout3000-2500yearsago.Bymeansoffouroverlappingprimers,wegotnucleotidesequenceofthe218bplength.AncientmtDNAwasanalyzedbythesequencingofhypervariableregionⅠofthemtDNAcontrolregion.Theresultshowsthat9haplotypeswith24polymorphicsiteswereobtained.ThephylogeneticanalysisindicatedthatMongoliansandAltaiarethepopulationgeneticallyclosesttotheJushigroupsandJushimtDNApoolbeinganadmixtureofeasternAsianandEuropeanlineages.SoourpreliminarydataimplythatanancientminglingofEuro-AsianpopulationhadexistedinTurfanbasinpriortotheearlyIronAge.
简介:Rheumatoidfactors(RFs)arethecharacteristicautoantibodiesofrheumatoidarthritis.Recentresearchesinourlaboratoryshowedthattheimmobilizedsingle-strandedDNA(ss-DNA)immunoadsorbentcanselectivelyremoveRFsfromtheserumofpatients.Inthepresentpaperarestudiedthemodificationofargininine,tryptophan,lysineresiduesandcarboxylterminusofIgGRF,whichwasseparatedfrompatients′serum,with1,2-cyclohexanedione(CHD),N-bromosuccinimide(NBS),pyridoxal5′-phosphate(PP)and1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide(EDC)respectively,andtheireffectsontheadsorptioncapacityoftheimmobilizedss-DNAimmunoadsorbentforIgGRF.Afterthespecificmodification,thecorrespondingadsorptioncapacitiesoftheadsorbentswerechangedfrom48%,46%,44%and54%to84%,14%,21%and81%,respectively.Theseresultsindicatethattheelectrostaticorionic-bondingisessentialfortheinteractionbetweenss-DNAandIgGRF.
简介:TheroleplayedbyDNAinmolecularbiologyisclearlyrecognizedtobevitaltolifeonthisplanet.8-oxo-7,8-dihydro-2deoxyguanosine(=8-OHdG),isprobablythemostimportantproductof"oxidativestress”inDNA.ItsconcentrationinDNAis,infact.aquantitativeanalysisofthedegreeofDNAdamagethatanorganismhasundergone.Duetotheimportanceof8-OHdGofnucleicacidginmutagenesis,carcinogenesisandaging,numerouschemicalandbiologicalinvestigationshavebeenmadeonthissubjectinthepasttime.Kuchinoandco-workershavefoundthat8-OHdGresidueinDNAismisreadingduringtheprocessofDNAreplication.Recently,somereportshavebeenpresentedonhigh8-OHdGlevelsinpatientssufferingfromvariousdiseasessuchaschronichepatitis,Fanconisanemia,diabetesmellitusandHelicobacterpyloriinfections.Asaresult,8-OHdGisausefulmarkerforthestudyofDNAdamagearisingfromreactiveoxygenspeciesandisofgreatsignificanceforcancerresearch.The8-OHdGlevelsinDNAcanhelpunderstandthemechanismofcarcinogensandleadtomoreeffectivetreatmentsformanydifferenttypesofcancer.Forthesereasons,ananalysisof8-OHdGwithquickness,lowcostandhighaccuracyisrequired.
简介:ThisstudyintendstoinvestigatehowtheelasticityofabacterialphagecanafecttheprocessofDNApackagingandejection.Forthispurpose,weproposeaunifiedcontinuumandstatisticalmechanicsmodelbytakingintoaccounttheefectsofDNAbendingdeformation,electrostaticrepulsionbetweenDNA–DNAstrandsandelasticdeformationofthephagecapsid.Basedonsuchamodel,wederivethequantitativerelationsbetweenpackagingforce,elasticityofcapsid,DNAlengthremaininginthecapsid,osmoticpressureandejectiontime.Thetheoreticallypredictedresultsarefoundtoagreeverywellwithinvitroexperimentalobservationsintheliterature.
简介:在文献中,DNA序列曾被描述为一维游动和三维游动.对前者,一个游动对应于多个DNA序列;对后者,游动和DNA序列一一对应.我们发现在三维游动(xn,yn,zn)中,由xn,yn和zn中任意有序的两个给出的二维游动已经与DNA序列一一对应,且余下的一维游动由该二维游动完全决定.因此,二维游动似乎是描述DNA序列最合适的模型.4个碱基A,C,G和T共有4!=24个排序.每一个排序都给出DNA序列用二维游动的一种描述.两个游动(x'n,y'n)和(x"n,y"n)被看作是等价的,如果(x'n,y'n)=(εx"n,δy"n)或(εy"n,δx"n),这里ε=±1,且δ=±1.于是这24个类型的游动被分成三个等价类;它们的代表分别是(xn,yn),(yn,zn),和(xn,zn),这里(xn,yn,zn)正好是张和张的三维游动.