Purotoxin-1(PT-1) isapeptideoriginallyisolatedfromtheCentralAsianspiderGeolycosa sp. Purotoxin-1 wasshowntoinhibitselectively P2X3receptorchannels ata100nMconcentration.Studieswerecarried-outonculturedratDRGneurons.Patch-clampexperimentsdidnotshowanyinhibitoryeffectofPT-1onvoltage-gatedchannels(potentialsrangetestedfrom-100to20mV),neitheronTRPV1(afteractivationwith500nMcapsaicin).Theselectivityof Purotoxin-1 forP2X3washighlightedbyactivatingthisreceptorwith10µMATPand100µMα,βMethylene-ATP.Indeed,unlikeP2X3,P2X2andheterodimerP2X2/3areknowntobenotsensitivetosuchconcentrations.Moreover,P2X3,P2X2,andP2X2/3aretheonlyknownATP-sensitivereceptorsexpressedinplasmamembranesofDRGneurons.So,theobservedeffectseemstobewellrelatedtoaselectiveinhibitionofP2X3.P2X3-mediatedcurrentwasfullyinhibitedwith100nMPurotoxin-1,makingitthemostpotentandselectiveligandforP2X3.
P2X3receptorsareknowntobeimplicatedinpainmechanisms.Behavioralexperimentationscarried-outonratpainmodelsusing0.5nmolPT-1injectedintraplantarshowedtoreducenociception.Thisanti-nociceptiveeffectiscomparabletoA-317491compound(Abbott’sdrug)withanamountofalmost3ordersofmagnitudelower.
Description:
AAsequence:Gly-Tyr-Cys3-Ala-Glu-Lys-Gly-Ile-Arg-Cys10-Asp-Asp-Ile-His-Cys15-Cys16-Thr-Gly-Leu-Lys-Cys21-Lys-Cys23-Asn-Ala-Ser-Gly-Tyr-Asn-Cys30-Val-Cys32-Arg-Lys-Lys-NH2
Disulfidebridges: Cys3-Cys16;Cys10-Cys21;Cys15-Cys32;Cys23-Cys30
Length(aa): 35
Formula: C155H248N50O48S8
Molecularweight: 3834.59Da
Appearance: Whitelyophilizedsolid
Solubility: waterandsalinebuffer
CASnumber:
Source: Synthetic
Purityrate: >97%
Reference:
ModulationofP2X3receptorsbyspidertoxins
Recently,thenovelpeptidenamedpurotoxin-1(PT1)hasbeenidentifiedinthevenomofthespiderGeolycosasp.andshowntoexertmarkedmodulatoryeffectsonP2X3receptorsinratsensoryneurons.Herewestudiedanotherpolypeptidefromthesamespidervenom,purotoxin-2(PT2),anddemonstratedthatitalsoaffectedactivityofmammalianP2X3receptors.ThemurineandhumanP2X3receptorswereheterologouslyexpressedincellsoftheCHOline,andnucleotide-gatedcurrentswerestimulatedbyCTPandATP,respectively.BothPT1andPT2negligIBLyaffectedP2X3-mediatedcurrentselicitedbybriefpulsesoftheparticularnucleotide.WhensubthresholdCTPorATPwasaddedtothebathtoexertthehigh-affinitydesensitizationofP2X3receptors,bothspidertoxinsstronglyenhancedthedesensitizingactionoftheambientnucleotides.Attheconcentrationof50nM,PT1andPT2elicited3-4-folddecreaseintheIC(50)doseofambientCTPorATP.Incontrast,100nMPT1andPT2negligiblyaffectednucleotide-gatedcurrentsmediatedbymP2X2receptorsormP2X2/mP2X3heteromers.Altogether,ourdatapointoutthatthePT1andPT2toxinsspecificallytargetthefast-desensitizingP2X3receptor,thusrepresentingauniquetooltomanipulateitsactivity.
PurinergicMembraneReceptorsasTargetsfortheEffectofPurotoxin1,aComponentofVenomofSpidersfromtheGeolycosaGenus
Weexaminedeffectsofpurotoxin1(PT1),acomponentofthevenomof Geolycosa spiders,onafewvoltageandligand-operatedionchannelspresentintheplasmamembraneofsensoryneuronsfromtheratdorsalrootganglia(DRGs).Purotoxin1ina100nMconcentrationevokednochangesinioncurrentsthroughvoltage-operatedsodium,potassium,andcalciumchannelsinthemembranesofisolatedsensoryneurons.Thisagentwasalsofoundtobeineffectivewithrespecttocapsaicin-sensitivereceptor-channelcomplexes(TRPV1).TestingoftheeffectsofPT1onpurinergicreceptor-channelcomplexesP2X3,P2X2,andP2X2/3showedthatthistoxinisahighlyselectiveblockerofexclusivelyP2X3receptors.TheselectivityofactionofPT1demonstratedinourexperimentsshowsthatitisauniqueagent,whichopensupnewProspectsinthestudiesofstructural/functionalpeculiaritiesofreceptor-channelcomplexesP2X3asaperipherallinkofthenociceptionsystem.
G.A.Savchenko, etal.(2010)PurinergicMembraneReceptorsasTargetsfortheEffectofPurotoxin1,aComponentofVenomofSpidersfromthe GeolycosaGenus. Neurophysiology.
NovelpeptidefromspidervenominhibitsP2X3receptorsandinflammatorypain
P2X3purinoreceptorsexpressedinmammaliansensoryneuronsplayakeyroleinseveralprocesses,includingpainperception.FromthevenomoftheCentralAsianspiderGeolycosasp.,wehaveisolatedanovelpeptide,namedpurotoxin-1(PT1),whichistoourknowledgethefirstnaturalmoleculeexertingpowerfulandselectiveinhibitoryactiononP2X3receptors.PT1dramaticallyslowsdowntheremovalofdesensitizationofthesereceptors.Thepeptidedemonstratespotentantinociceptivepropertiesinanimalmodelsofinflammatorypain.
E.V.Grishin, etal.(2010)NovelpeptidefromspidervenominhibitsP2X3receptorsandinflammatorypain. ANNNEUROL. PMID:20437566
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常用流动相加酸碱后PH的总结，希望大家能够提供一点自己测过的结果，谢谢先
1.直接用固体磷酸钠配制成50mM的磷酸钠溶液，再调pH到7.4；（我们试着用这个做了下，发现挂不上柱）
2.配置磷酸钠盐缓冲液：按NaH2PO4：Na2HPO4以19：81的摩尔比配制成pH7.4的缓冲液？（附一张百度出来的配方
）
3.如果是磷酸钠盐缓冲液，可以直接将50mM的NaH2PO4的水溶液用NaOH调成pH7.4吗？
再者，2和3这两个方法配制的磷酸钠盐缓冲液有什么区别？最终效果是一样的吗？如果不一样，有什么理论的知识支撑呢？个人感觉是分析化学中酸碱理论中的缓冲液那里的知识。求帮忙解答这些疑问。
另外，我还想问一下，pH对于Ni柱对His-tagged的蛋白的分离纯化影响大吗？是怎么影响的？谢谢大家了！
有了源数据之后把源数据按照大小排列，
选中源数据区域-->ALT+A1-->选中图标区右键-->更改图表类型-->散点图
因为是考察不同PH对药物的影响，样品又不好改变其PH值，这种情况怎么办？希望有经验的高手指教。
我的流动相是甲醇-水（90：10）
谢谢赐教！
请进子版按格式发贴，自行修改，谢谢。
由弱酸及其盐、弱碱及其盐组成的混合溶液，能在一定程度上抵消、减轻外加强酸或强碱对溶液酸碱度的影响，从而保持溶液的pH值相对稳定。这种溶液称为缓冲溶液。
:)
我在做一细菌不同酸碱度生长状况时,发现这些奇怪现象:pH=3的培养基灭菌(TSB液体培养基)灭菌后pH上升到到9.2!而原来pH=9.0的降到8.7(基本没多少变化),请问各位大侠,这是什么原因?
一般做不同酸碱度生长实验时,该如何才能防止pH在湿热灭菌后基本不变化?
是否可以理解为纯化水得PH范围为6.3-7.6？能否直接用pH计测量？谢谢!
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