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:高速光电探测器阵列可对脉冲辐射场的时空分布进行高时间分辨连续测量,但对信号处理电路的性能和紧凑性提出了极为苛刻的要求。探测器阵列的信号处理主要包括探测器模拟信号调理前端和高速模拟信号实时采样处理后端。针对32通道1维光电探测器阵列,设计实现了后端实时信号处理系统。该系统采用多通道高速ADC和FPGA实现了探测器模拟信号的12bit量化,采样频率为75MHz;针对多通道ADC输出的高速串行信号,设计实现了低开销的时钟对齐与帧识别电路,时钟对齐精度为78ps,保证了对多路高速串行数据的正确获取;基于高性能FPGA,实现了对32个采样通道数据的实时处理与存储,信号处理电路的数据获取和实时处理速度达28.8Gb/s。
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.