ProtoxinI(ProTx-I;β-theraphotoxin-Tp1a) isatoxinthatwasoriginallyisolatedfromthevenomofThrixopelmapruriens(Peruviangreenvelvettarantula).ThistoxinreversIBLyinhibitsthetetrodotoxin(TTX)-resistantchannel Nav1.8(IC50 =27nM)and Nav1.2,Nav1.5andNav1.7 withIC50 valuesbetween50and100nM.FurThermore, ProTx-I shiftsthevoltagedependenceactivityof T-typeCav3.1channels (IC50=50nM)withoutaffectingthevoltagedependenceofinactivation. ProTx-I isavaluabletooltodiscriminatebetweenCav3.1andCav3.2
Description:
AAsequence:Glu-Cys2-Arg-Tyr-Trp-Leu-Gly-Gly-Cys9-Ser-Ala-Gly-Gln-Thr-Cys15-Cys16-Lys-His-Leu-Val-Cys21-Ser-Arg-Arg-His-Gly-Trp-Cys28-Val-Trp-Asp-Gly-Thr-Phe-Ser-OH
Disulfidebridges:Cys2-Cys16,Cys9-Cys21,Cys15-Cys28
Length(aa):35
Formula:C171H245N53O47S6
MolecularWeight:3987.50Da
Appearance:Whitelyophilizedsolid
Solubility:waterorsalinebuffer
CASnumber:Notavailable
Source:Synthetic
Purityrate:>95%
Reference:
Twotarantulapeptidesinhibitactivationofmultiplesodiumchannels
Twopeptides,ProTx-IandProTx-II,fromthevenomofthetarantulaThrixopelmapruriens,havebeenisolatedandcharacterized.ThesepeptideswerepurifiedonthebasisoftheirABIlitytoreversiblyinhibitthetetrodotoxin-resistantNachannel,Na(V)1.8,andareshowntobelongtotheinhibitorycystineknot(ICK)familyofpeptidetoxinsinteractingwithvoltage-gatedionchannels.Thefamilyhasseveralhallmarks:cystinebridgeconnectivity,mechanismofchannelinhibition,andpromiscuityacrosschannelswithinandacrosschannelfamilies.ThecystinebridgeconnectivityofProTx-IIisverysimilartothatofothermembersofthisfamily,i.e.,C(2)toC(16),C(9)toC(21),andC(15)toC(25).Thesepeptidesarethefirsthigh-affinityligandsfortetrodotoxin-resistantperipheralnerveNa(V)channels,butalsoinhibitotherNa(V)channels(IC(50)’s<100nM).ProTx-IandProTx-IIshiftthevoltagedependenceofactivationofNa(V)1.5tomorepositivevoltages,similartoothergating-modifierICKfamilymembers.ProTx-IalsoshiftsthevoltagedependenceofactivationofCa(V)3.1(alpha(1G),T-type,IC(50)=50nM)withoutaffectingthevoltagedependenceofinactivation.Toenablefurtherstructuralandfunctionalstudies,syntheticProTx-IIwasmade;itadoptsthesamestructureandhasthesamefunctionalpropertiesasthenativepeptide.SyntheticProTx-Iwasalsomadeandexhibitsthesamepotencyasthenativepeptide.SyntheticProTx-I,butnotProTx-II,alsoinhibitsK(V)2.1channelswith10-foldlesspotencythanitspotencyonNa(V)channels.ThesepeptidesrepresentnoveltoolsforexploringthegatingmechanismsofseveralNa(V)andCa(V)channels.
MiddeltonR.E, etal. (2002)Twotarantulapeptidesinhibitactivationofmultiplesodiumchannels.Biochemestry.PMID: 12475222
ProTx-IandProTx-II:gatingmodifiersofvoltage-gatedsodiumchannels
ThetarantulavenompeptidesProTx-IandProTx-IIinhibitvoltage-gatedsodiumchannelsbyshiftingtheirvoltagedependenceofactivationtoamorepositivepotential,thusactingbyamechanismsimilartothatofpotassiumchannelgatingmodifierssuchashanatoxinandVSTX1.ProTx-IandProTx-IIinhibitallsodiumchannel(Nav1)subtypestestedwithsimilarpotencyandrepresentthefirstpotentpeptidylinhibitorsofTTX-resistantsodiumchannels.Likegatingmodifiersofpotassiumchannels,ProTx-IandProTx-IIconformtotheinhibitorycystineknotmotif,andProTx-IIwasdemonstratedtobindtosodiumchannelsintheclosedstate.Bothtoxinshavebeensynthesizedchemically,andProTx-II,producedbyrecombinantmeans,hasbeenusedtomaptheinteractionsurfaceofthepeptidewiththeNav1.5channel.Incomparison,beta-scorpiontoxinsactivatesodiumchannelsbyshiftingthevoltagedependenceofactivationtomorenegativepotentials,andtogetherthesepeptidesrepresentvaluabletoolsforexploringthegatingmechanismofsodiumchannels.
PriestB.T., etal.(2007)ProTx-IandProTx-II:gatingmodifiersofvoltage-gatedsodiumchannels. Toxicon.PMID: 17087985
TarantulatoxinProTx-IdifferentiatesbetweenhumanT-typevoltage-gatedCa2+ChannelsCav3.1andCav3.2
ProTx-Ipeptide,avenomtoxinofthetarantulaThrixopelmapruriens,hasbeenreportedtointeractwithvoltage-gatedionchannels.ProTx-IreducedBa(2+)currentsthroughrecombinanthumanT-typevoltage-gatedCa(2+)channels,Ca(v)3.1(hCa(v)3.1),withroughly160-foldmorepotencythanthroughhCa(v)3.2channels.Chimericchannelproteins(hCa(v)3.1/S3S4andhCa(v)3.2/S3S4)wereproducedbyexchangingfourteenaminoacidsinthehCa(v)3.1domainIVS3-S4linkerregionandthecorrespondingregionofhCa(v)3.2betweeneachother.TheProTx-IsensitivitywasmarkedlyreducedinthehCa(v)3.1/S3S4chimeraascomparedtotheoriginalhCa(v)3.1channel,whilethehCa(v)3.2/S3S4chimeraexhibitedgreaterProTx-IsensitivitythantheoriginalhCa(v)3.2channel.TheseresultssuggestthatthedomainIVS3-S4linkerinthehCa(v)3.1channelmaycontainresiduesinvolvedintheinteractionofProTx-IwithT-typeCa(2+)channels.
OhkuboT, etal. (2010)TarantulatoxinProTx-IdifferentiatesbetweenhumanT-typevoltage-gatedCa2+ ChannelsCav3.1andCav3.2. JPharmacolSci. PMID: 20351484
ATarantula-VenomPeptideAntagonizestheTRPA1NociceptorIonChannelbyBindingtotheS1-S4GatingDomain
BACKGROUND:
Thevenomsofpredatorshavebeenanexcellentsourceofdiversehighlyspecificpeptidestargetingionchannels.HerewedescribethefirstknownpeptideantagoNISTofthenociceptorionchanneltransientreceptorpotentialankyrin1(TRPA1).
RESULTS:
WeconstructedarecombinantCDNAlibraryencoding∼100diverseGPI-anchoredpeptidetoxins(t-toxins)derivedfromspidervenomsandscreenedthislibrarybycoexpressioninXenopusoocyteswithTRPA1.Thisscreenresultedinidentificationofprotoxin-I(ProTx-I),a35-residuepeptidefromthevenomofthePeruviangreen-velvettarantula,Thrixopelmapruriens,asthefirstknownhigh-affinitypeptideTRPA1antagonist.ProTx-Iwaspreviouslyidentifiedasanantagonistofvoltage-gatedsodium(NaV)channels.Weconstructedat-toxinlibraryofProTx-Ialanine-scanningmutantsandscreenedthislibraryagainstNaV1.2andTRPA1.ThisrevealeddistinctpartiallyoverlappingsurfacesofProTx-Ibywhichitbindstothesetwoionchannels.Importantly,thismutagenesisyieldedtwonovelProTx-IvariantsthatareonlyactiveagainsteitherTRPA1orNaV1.2.Bytestingitsactivityagainstchimericchannels,weidentifiedtheextracellularloopsoftheTRPA1S1-S4gatingdomainastheProTx-Ibindingsite.
CONCLUSIONS:
Thesestudiesestablishourapproach,whichweterm“toxineering,”asagenerallyapplicablemethodforisolationofnovelionchannelmodifiersanddesignofionchannelmodifierswithalteredspecificity.TheyalsosuggestthatProTx-IwillbeavaluablepharmacologicalreagentforaddressingbiophysicalmechanismsofTRPA1gatingandthephysiologyofTRPA1functioninnociceptors,aswellasforpotentialclinicalapplicationinthecontextofpainandinflammation.
GuiJ,etal.(2014)ATarantula-VenomPeptideAntagonizestheTRPA1NociceptorIonChannelbyBindingtotheS1-S4GatingDomain. CurrBiol. PMID: 24530065
ebiomall.com
>
>
>
>
>
>
>
>
>
>
>
>
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!
暂无品牌分类
© 2005- 苏州蚂蚁淘生物科技有限公司 版权所有。
苏ICP备17049038号-11
苏公网安备 32059002001627号
声明：本网站部分产品受外界条件影响（包含但不限于进口国出口国政策限制等因素），无法提供销售服务，下单后，会由客服人员联系厂家确认后另行通知。部分危险品无法清关，请勿下单