电子自旋共振经典讲座演示文稿

电子自旋共振经典讲座演示文稿当前1页，总共23页。优选电子自旋共振经典讲座当前2页，总共23页。FreeRadicalsandEPRMoleculeswithoneormoreunpairedelectronQuantummechanics:unpairedelectronshavespinandchargeandhencemagneticmomentElectronicspincanbeineitheroftwodirections(formallyupordown)ThetwospinstatesundernormalconditionsareenergeticallydegenerateEnergeticdegeneracylostwhenexposedtoanexternalmagneticfield当前3页，总共23页。TheEPRexperimentPutsampleintoexperimentalmagneticfield(B)Irradiate(microwavefrequencies)Measureabsorbanceofradiationasf(B)Weil,Bolton,andWertz,1994,“ElectronParamagneticResonance”当前4页，总共23页。TheEPRspectrometerElectromagnetMicrowavesourceanddetector(typicallyXband,~9.5GHz)Modulationofmagneticfieldandphase-sensitivedetectionSpectrum1stderivativeWeil,Bolton,andWertz,1994,“ElectronParamagneticResonance”当前5页，总共23页。TheEPRspectrumA1stderivativespectrumisobtainedfromtheunpairedelectronhn=gBb0gisacharacteristicofthechemicalenvironmentoftheunpairedelectron;forfreeradicalsitisnear2.00;canvarywidelyfortransitionmetalcentersComplicated/enhancedbyhyperfineinteractionswithnucleiwithnon-zerospin当前6页，总共23页。ThehyperfineeffectThemagneticfieldexperiencedbytheunpairedelectronisaffectedbynearbynucleiwithnon-zeronuclearspinWeil,Bolton,andWertz,1994,“ElectronParamagneticResonance”,NewYork:WileyInterscience.当前7页，总共23页。HyperfinesplittingofEPRspectraThemagnitudeofthesplittingandthenumberoflinesdependupon:Thenuclearspinoftheinteractingnucleus#oflines=2n(I+½)soI=½gives2lines,etc.ThenucleargyromagneticratioThemagnitudeoftheinteractionbetweentheelectronicspinandthenuclearspinMagnitudeofthesplittingtypicallydecreasesgreatlywithincreasingnumbersofbondsbetweenthenucleusandunpairedelectron当前8页，总共23页。当前9页，总共23页。Hyperfinesplittingsareadditive当前10页，总共23页。DirectEPRanalysisofaradicalRadicalcannotbediatomicRadicalmustbeavailableatadetectableconcentrationAtleastmetastableFrozensolutiontogreatlydecreaseradicaldecayCangreatlycomplicatethespectrumduetoanisotropyContinuousformationinsideresonatorEnzymaticradicalformationFlowexperimentRadicalcharacterizedbyhyperfineanalysis当前11页，总共23页。DirectEPRofatyrosylradicalGunther,M.R.,Sturgeon,B.E.,andMason,R.P.,FreeRadic.Biol.Med.28:709-719,2000当前12页，总共23页。Spintrapping:whendirectEPRisnotconvenientorpossibleUnstablefreeradicalreactswithdiamagneticmolecule(thespintrap)toformarelativelystablefreeradicalThevastmajorityofspintrapsformradicaladductsthroughtheadditionoftheradicaltothetraptoformanitroxideradical2majorclassesoftraps:nitronesandnitrosocompounds当前13页，总共23页。AdvantagesofthenitronesReactwithavarietyofdifferentfreeradicalstoformnitroxideadductsRC.,RO.,RS.,insomecasesRN.AdductsareoftenquitestableNotterriblytoxicsoamenabletoinvivo/exvivospintrapping当前14页，总共23页。NitronespintrapsDMPO,5,5-dimethylpyrrolineN-oxidePBN/4-POBN,phenyl-N-t-butylnitrone当前15页，总共23页。EPRspectrafromDMPOadducts当前16页，总共23页。EPRspectrafrom4-POBNadducts当前17页，总共23页。NitrosospintrapsFreeradicaladdstothenitrogenatomofaC-nitrosocompound2-methyl-2-nitrosopropane,MNP3,5-dibromo-4-nitrosobenzenesulfonate当前18页，总共23页。EPRspectrafrommethylradicaladductsofnitrosotraps当前19页，总共23页。DMPO-trappingthetyrosylradicalOxidizetyrosinewithHRP/H2O2Gunther,M.R.,etal.,Biochem.J.330:1293-1299,1998.当前20页，总共23页。Spintrap-derivedhyperfinefromMNPandMNP-d9EachlineintheEPRspectrafromMNPadductsisbroadenedbyhyperfinefromthe9equivalentprotonsonthespintrap当前21页，总共23页。MNP-trappingthetyrosylradicalGunther,M.R.,etal.,Biochem.J.330:1293-1299,1998.当前22页，总共23页。Whynotspintrap?Nitronespintraps,especiallyDMPOAdductscaninterconv