Description: TheBioLux®
Gaussia LuciferaseAssayKitcontainsthereagentsnecessaryforassaying
Gaussia Luciferase(GLuc)activity,mostcommonlyfromcellculturesupernatants.
Gaussia Luciferaseisareporterluciferasefromthemarinecopepod
Gaussia princeps(1,2).
Gaussia Luciferasecanbeexpressedinmammaliancellsusingreporterplasmidsavailablefrom
NEB (RefertotheCompanionProducts).Thisluciferase,whichdoesnotrequireATP,catalyzestheoxidationofthesubstratecoelenterazineinareactionthatproduceslight(Figure1),andhasconsiderableadvantagesoverotherluminescentreportergenes.
ThiskitnowincludesanadditionalstABI lizercomponent,whichallowstheuseoftheassayinhighthroughputformatorwithouttherequirementofaninjector-equippedluminometer. Thisthree-componentassaysystemprovidestheuserwith2options:(a)usetheassaywithoutstabilizerforenhancedlightoutputor(b)usewiththedesiredamountofstabilizerforenhancedsignalstability.Thestabilizercomponentallowstheuseoftheassayinhighthroughputformatorwithouttherequirementofaninjector-luminometer. Forstandardassaysgivingthehighestactivity,thekitcanbeusedwiththeGLucsubstratemixedintheassaybuffer.Withthestabilizedassayprotocols,thelightemissiondecaysslowlywithahalf-lifeofapproximately25minutes.Theadditionofstabilizerdecreasestheabsolutevalueoflightoutputbutconferssignalstabilityovertime(Figure2).
TheluminescencemeasuredfromthesupernatantofculturedcellstransfectedwithaplasmidexpressingGLucisproportionaltotheamountofenzymeproduced,whichinturn,reflectstheleveloftranscription.Alternatively,acelllysatesamplecanbeusedfortheassay.AlthoughmostoftheGLucissecreted,thehighsensitivityofGLucallowsmeasurementsfromthecellularfraction.
Figure1:ThePhoto-oxidationcatalyzedbyGaussia Luciferase. Haddock,S.H.D.,McDougall,C.M.andCase,J.F.,TheBioluminescenceWebPage,http://Lifesci .ucsb.edu/~biolum/(created1997;updated2005).Figure2:GLuckineticsusingtheBioLuxGLucAssayKitineitherstandardorstabilizedassay. Assaysweresetupusingassaysolutionwithoutstabilizerorwiththeindicatedamountsofstabilizer(5µL,8µLor10µLofstabilizerper50µLGLucassaysolution).Figure3:StabilityofGaussia Luciferaseatvarioustemperatures. GrowthmediafromGLuc-expressingcells(GLuc-sup)wereincubatedat95°Cand55°Cfor30minutesandallowedtocooltoroomtemperature(25°C)beforeassayingforGLucactivity.Figure4:StabilityofGaussia Luciferaseat37°Coveraperiod ofsevendays. GrowthmediafromGLuc-expressingcellsgrownin±β-mercaptoethanol-containingmedia(GLuc-sup&GLuc-sup,β-mercaptoEtOH)wereplacedat37°Candassayedeverydayforaperiodofsevendays.Figure5:Gaussia LuciferaseactivityafteraddingGLucassaysolutioncontainingstabilizertoasample. TheGLucassaysolutioncontainingstabilizer(i.e.8μlofstabilizerper50μlGLucassaysolution)wasaddedtoaGLucsampleandthemeasurementsweretakenat1-secondincrements(seeUsageNotes). KitComponents Thefollowingreagentsaresuppliedwiththisproduct:
Storeat(°C) Concentration BioLux® GLucAssayBuffer 4 1X BioLux® GLucSubstrate -20 100X BioLux® GLucStabilizer 4 100X
Notes: BecauseofthestabilityofGLuc,theactivitymeasuredinthegrowthmediaofGLuc-expressingculturereflectstheproteinthathasaccumulateduptothetimeofsampling.Forthestandardassaysolution,i.e.solutionthatdoesnotcontainstabilizer,equilibrationoftheassaysolutionisnotnecessary.AfteraddingtheGLucassaysolutiontothesample,werecommendadelayof1-5secondsbeforetakingameasurement.Keepingthedelaytimeconsistentacrossexperimentswillensurereproducibility.Forthestabilizedassaysolution,i.e.,thestabilizer-containingGLucassaysolution,thesolutionshouldbeequilibratedatroomtemperaturefor25minutes(protectfromlightinatightlycappedtube/bottle)beforeaddingtothesample.AfteraddingtheequilibratedGLucassaysolutiontothesample,werecommendadelaytimeof35-40secondsbeforetakingameasurementinordertoreachmaximumlevelofdetection.ThisisespeciallyimportantwhentheGLucactivitylevelislow(e.g.<e4RLU).Forexample,thereadoutobtainedafter35-40secondsofdelayis~e4;whencompareto30,20and10secondsofdelay,thereadoutsareasfollows:~2%decrease(for30secondsofdelay),~7%decrease(for20secondsofdelay),&~20%decrease(for10secondsofdelay)inRLU(refertoFigure5).UsethepreparedGLucassaysolutionwithin24hours.Theunusedportionoftheassaysolutionshouldtightlycappedandstoredat-20˚C.Itshouldbecompletelythawed(inthedark)atroomtemperaturebeforeuse.Thelinearrangeoftheluminometerusedfortheassaymustbeestablished.Thisiseasilydonebyassayingserialdilutionsofasample.Inaddition,theassaysolutionitself,aswellastheconditionedmedia(i.e.growthmediafromuntransfectedcells)shouldbeincludedintheassaytoestablishthebackgroundsignalintheassay.Ifexcessactivityfortheinstrumentrangeisfound,thesampleshouldbedilutedineitherPBSor10%serum-containingmedia.Theintegrationtimecanalsobereduced.Whenassayingtheserialdilutionofasample,itisbesttoassaythemostdilutedsamplesfirstandthemostconcentratedsampleslast.Thiswillhelptominimizefalsere
ADI ngs,i.e.,cross-talkeffect(signalsfromsamplesofhighRLUcrossintothatofthenextsample).Thecross-talkeffectseemstobemorepronouncedwhenplates(whiteorblack)withclear-bottomsareused.TheBioLuxGLucAssayBufferandtheBioLuxGLucStabilizercanbestoredat4˚CwhiletheBioLuxGLucSubstratemustbestoredat-20˚C.