BlockerofhighconductanceCa2+-activatedK+channel
Iberiotoxin(IbTx)isatoxinthatwasoriginallyisolatedfromButhustamulusscorpionvenom.IberiotoxininhibitsselectivelythehighconductanceCa2+-activatedK+channel(KCa1.1)atnanomolarconcentrations(IC50~2nM).Thistoxindoesnotaffectothertypesofcalcium-dependentorvoltage-dependentK+channels.IberiotoxinisavaluabletooltostudyspecificallyMaxi-Kchannels.
RecentlyquotedinBr.J.Pharmacol.
Description:
AAsequence:pGlu-Phe-Thr-Asp-Val-Asp-Cys-Ser-Val-Ser-Lys-GIu-Cys-Trp-Ser-Val-Cys-Lys-Asp-Leu-Phe-Gly-Val-Asp-Arg-Gly-Lys-Cys-Met-Gly-Lys-Lys-Cys-Arg-Cys-Tyr-GIn-OH
Disulfidebridges:Cys7-Cys28,Cys13-Cys33,Cys17-Cys35
Length(aa):37
Formula:C179H274N50O55S7
MolecularWeight:4230.8Da
Appearance:Whitelyophilizedsolid
Solubility:waterandsalinebuffer
CASnumber:129203-60-7
Source:Synthetic
Purityrate:>95%
Reference:
EffectsofthenovelBK(KCa1.1)channelopenerGoSlo-SR-5-130aredependentonthepresenceofBKβsubunits.
GoSlo-SRcompoundsareefficaciousBK(KCa1.1)channelopeners,butlittleisknownabouttheirmechanismofactionoreffectonbladdercontractility.WeexaminedtheeffectsoftwocloselyrelatedcompoundsonBKcurrentsandbladdercontractions.Acombinationofelectrophysiology,molecularBIOLOGyandsyntheticchemistrywasusedtoexaminetheeffectsoftwonovelchannelagoNISTsonBKchannelsfrombladdersmoothmusclecellsandinHEKcellsexpressingBKαaloneorincombinationwitheitherβ1orβ4subunits.GoSlo-SR-5-6shiftedthevoltagerequiredforhalfmaximalactivation(V1/2)ofBKchannelsapproximately-100 mV,irrespectiveofthepresenceofregulatoryβsubunits.Thedeaminatedderivative,GoSlo-SR-5-130,alsoshiftedtheactivationV1/2insmoothmusclecellsbyapproximately-100 mV;however,thiswasreducedby∼80%inHEKcellsexpressingonlyBKαsubunits.Whenβ1orβ4subunitswereco-expressedwithBKα,efficacywasrestored.GoSlo-SR-5-130causedaconcentration-dependentreductioninspontaneousbladdercontractionamplitudeandthiswasabolishedbyiberiotoxin,consistentwithaneffectonBKchannels.GoSlo-SR-5-130requiredβ1orβ4subunitstomediateitsfulleffects,whereasGoSlo-SR-5-6workedequallywellintheabsenceorpresenceofβsubunits.GoSlo-SR-5-130inhibitedspontaneousbladdercontractionsbyactivatingBKchannels.ThenovelBKchannelopener,GoSlo-SR-5-130,isapproximatelyfivefoldmoreefficaciousonBKchannelswithregulatoryβsubunitsandmaybeausefulscaffoldinthedevelopmentofdrugstotreatdiseasessuchasoveractivebladder.
LargeRJ.,etal.(2015)EffectsofthenovelBK(KCa1.1)channelopenerGoSlo-SR-5-130aredependentonthepresenceofBKβsubunits.BJP.PMID:25598230
Purificationandcharacterizationofaunique,potent,peptidylprobeforthehighconductancecalcium-activatedpotassiumchannelfromvenomofthescorpionButhustamulus
Aninhibitorofthehighconductance,Ca2(+)-activatedK+channel(PK,Ca)hasbeenpurifiedtohomogeneityfromvenomofthescorpionButhustamulusbyacombinationofionexchangeandreversed-phasechromatography.Thispeptide,whichhasbeennamediberiotoxin(IbTX),isoneoftwominorcomponentsofthecrudevenomwhichblocksPK,Ca.IbTXconsistsofasingle4.3-kDapolypeptidechain,asdeterminedbypolyacrylamidegelelectrophoresis,analysisofaminoacidcomposition,andEdmandegradation.Itscompleteaminoacidsequencehasbeendefined.IbTXdisplays68%sequencehomologywithcharyBDotoxin(ChTX),anotherscorpion-derivedpeptidylinhibitorofPK,Ca,and,likethislattertoxin,itsaminoterminuscontainsapyroglutamicacidresidue.However,IbTXpossesses4moreacidicand1lessbasicaminoacidresiduethandoesChTX,makingthistoxinmuchlesspositivelychargedthantheotherpeptide.Insinglechannelrecordings,IbTXreversIBLyblocksPK,Cainexcisedmembranepatchesfrombovineaorticsmoothmuscle.ItactsexclusivelyattheouterfaceofthechannelandfunctionswithanIC50ofabout250pM.BlockofchannelactivityappearsdistinctfromthatofChTXsinceIbTXdecreasesboththeprobABIlityofchannelopeningaswellasthechannelmeanopentime.IbTXisaselectiveinhibitorofPK,Ca;itdoesnotblockothertypesofvoltage-dependentionchannels,especiallyothertypesofK+channelsthataresensitivetoinhibitionbyChTX.IbTXisapartialinhibitorof125I-ChTXbindinginbovineaorticsarcolemmalmembranevesicles(Ki=250pM).ThemaximalextentofinhibitionthatoccursismodulatedbyK+,decreasingasK+concentrationisraised,butK+doesnotaffecttheabsoluteinhibitorypotencyofIbTX.AScatchardanalysisindicatesthatIbTXfunctionsasanoncompetitiveinhibitorofChTXbinding.Takentogether,thesedatasuggestthatIbTXinteractsatadistinctsiteonthechannelandmodulatesChTXbindingbyanallostericmechanism.Therefore,IbTXdefinesanewclassofpeptidylinhibitorofPK,Cawithuniquepropertiesthatmakeitusefulforinvestigatingthecharacteristicsofthischannelintargettissues.
GalvezA,etal.Purificationandcharacterizationofaunique,potent,peptidylprobeforthehighconductancecalcium-activatedpotassiumchannelfromvenomofthescorpionButhustamulus.JBiolChem.PMID: 1694175
Mechanismofiberiotoxinblockofthelarge-conductancecalcium-activatedpotassiumchannelfrombovineaorticsmoothmuscle
Theinteractionofiberiotoxin(IbTX)withthelarge-conductancecalcium-activatedpotassium(maxi-K)channelwasexaminedbymeasuringsingle-channelcurrentsfrommaxi-Kchannelsincorporatedintoplanarlipidbilayers.AdditionofnanomolarconcentrationsofIbTXtotheexternalsideofthechannelproducedlongnonconductingsilentperiods,whichwereinterruptedbyperiodsofnormalchannelactivity.Thedistributionsofdurationsofblockedandunblockedperiodswerebothdescribedbysingleexponentials.ThemeandurationoftheunblockedperiodsdecreasedinproportionwiththeexternalconcentrationofIbTX,whilethemeandurationoftheblockedperiodswasnotaffected.TheseresultssuggestthatIbTXblocksthemaxi-Kchannelthroughasimplebimolecularbindingreactionwherethesilentperiodsrepresenttimeswhenasingletoxinmoleculeisboundtothechannel.Insymmetricsolutionsof150mMKCl,withamembranepotentialof40mV,themeandurationoftheblockedperiodsproducedbyIbTXwas840s,andtheassociationratewas1.3x10(6)M-1s-1,yieldinganequilibriumdissociationconstantofabout1nM.RaisingtheinternalpotassiumconcentrationincreasedthedissociationrateconstantofIbTXinamannerwhichwaswelldescribedbyasaturablebindingfunctionforpotassium.Externaltetraethylammoniumionincreasedtheaveragedurationoftheunblockedperiodswithoutaffectingtheblockedperiods,suggestingthattetraethylammoniumandIbTXcompeteforthesamesiteneartheconductancepathwayofthechannel.Increasingtheexternalconcentrationofmonovalentcationsfrom25to300mMwitheitherpotassiumorsodiumdecreasedtherateofbindingofIbTXtothechannelbyapproximately24-fold,withlittleeffectontherateoftoxindissociation.
GiangiacomoKM,etal.Mechanismofiberiotoxinblockofthelarge-conductancecalcium-activatedpotassiumchannelfrombovineaorticsmoothmuscle.Biochemistry.PMID: 1379069
High-conductancecalcium-activatedpotassiumchannels;structure,pharmacology,andfunction
High-conductancecalcium-activatedpotassium(maxi-K)channelscompriseaspecializedfamilyofK+channels.TheyareuniqueintheirdualrequirementfordepolarizationandCa2+bindingfortransitiontotheopen,orconducting,state.Ionconductionthroughmaxi-Kchannelsisblockedbyafamilyofvenom-derivedpeptides,suchascharybdotoxinandiberiotoxin.Thesepeptideshavebeenusedtostudyfunctionandstructureofmaxi-Kchannels,toidentifynovelchannelmodulators,andtofollowthepurificationoffunctionalmaxi-Kchannelsfromsmoothmuscle.Thechannelconsistsoftwodissimilarsubunits,alphaandbeta.ThealphasubunitisamemberofthesloCa(2+)-activatedK+channelgenefamilyandformstheionconductionpore.Thebetasubunitisastructurallyunique,membrane-spanningproteinthatcontributestochannelgatingandpharmacology.Potent,selectivemaxi-Kchanneleffectors(bothagonistsandblockers)oflowmolecularweighthavebeenidentifiedfromnaturalproductsources.Theseagents,togetherwithpeptidylinhibitorsandsite-directedantibodiesraisedagainstalphaandbetasubunitsequences,canbeusedtoanatomicallymapmaxi-Kchannelexpression,andtostudythephysiologicroleofmaxi-Kchannelsinvarioustissues.Onegoalofsuchinvestigationsistodeterminewhethermaxi-Kchannelsrepresentnoveltherapeutictargets.
KaczorowskiGJ,etal.High-conductancecalcium-activatedpotassiumchannels;structure,pharmacology,andfunction.JBioenergBiomembr. PMID: 8807400
Useoftoxinstostudypotassiumchannels
Potassiumchannelscomprisegroupsofdiverseproteinswhichcanbedistinguishedaccordingtoeachmember’sbiophysicalproperties.SometypesofK+channelsareblockedwithhighaffinitybyspecificpeptidyltoxins.Threetoxins,charybdotoxin,iberiotoxin,andnoxiustoxin,whichdisplayahighdegreeofhomologyintheirprimaryaminoacidsequences,havebeenpurifiedtohomogeneityfromscorpionvenom.Whilecharybdotoxinandnoxiustoxinareknowntoinhibitmorethanoneclassofchannel(i.e.,severalCa(2+)-activatedandvoltage-dependentK+channels),iberiotoxinappearstobeaselectiveblockerofthehigh-conductance,Ca(2+)-activatedK+channelthatispresentinmuscleandneuroendocrinetissue.Adistinctclassofsmall-conductanceCa(2+)-activatedK+channelisblockedbytwoothertoxins,apaminandleiurotoxin-1,thatsharenosequencehomologywitheachother.Afamilyofhomologoustoxins,thedendrotoxins,havebeenpurifiedfromvenomofvariousrelatedspeciesofsnakes.Thesetoxinsinhibitseveralinactivatingvoltage-dependentK+channels.Althoughmolecularbiologyapproacheshavebeenemployedtoidentifyandcharacterizeseveralspeciesofvoltage-gatedK+channels,toxinsdirectedagainstaparticularchannelcanstillbeusefulindefiningthephysiologicalroleofthatchannelinaparticulartissue.Inaddition,forthoseK+channelswhicharenotyetsuccessfullyprobedbymolecularbiologytechniques,toxinscanbeusedasbiochemicaltoolswithwhichtopurifythetargetproteinofinterest.
GarciaML,etal.Useoftoxinstostudypotassiumchannels.JBioenergBiomembr. PMID: 1917911
Modeofactionofiberiotoxin,apotentblockerofthelargeconductanceCa(2+)-activatedK+channel
Iberiotoxin,atoxinpurifiedfromthescorpionButhustamulusisa37aminoacidpeptidehaving68%homologywithcharybdotoxin.CharybdotoxinblockslargeconductanceCa(2+)-activatedK+channelsatnanomolarconcentrationsfromtheexternalsideonly(Miller,C.,E.Moczydlowski,R.Latorre,andM.Phillips.1985.Nature(Lond.).313:316-318).Likecharybdotoxin,iberiotoxinisonlyabletoblocktheskeletalmusclemembraneCa(2+)-activatedK+channelincorporatedintoneutral-planarbilayerswhenappliedtotheexternalside.Inthepresenceofiberiotoxin,channelactivityisinterruptedbyquiescentperiodsthatcanlastforseveralminutes.Fromsingle-channelrecordsitwaspossibletodeterminethatiberiotoxinbindstoCa(2+)-activateK+channelinabimolecularreaction.Whenthesolutionbathingthemembraneare300mMK+internaland300mMNa+externalthetoxinsecondorderassociationrateconstantis3.3x10(6)s-1M-1andthefirstorderdissociationrateconstantis3.8x10(-3)s-1,yieldinganapparentequilibriumdissociationconstantof1.16nM.Thisconstantis10-foldlowerthanthatofcharybdotoxin,andthevaluesfortherateconstantsshowedaboveindicatethatthisismainlyduetotheverylowdissociationrateconstant;meanblockedtimeapproximately5min.Thefactthattetraethylammoniumcompetitivelyinhibitstheiberiotoxinbindingtothechannelisastrongsuggestionthatthistoxinbindstothechannelexternalvestibule.IncreasingtheexternalK+concentrationmakestheassociationrateconstanttodecreasewithnoeffectonthedissociationreactionindicatingthatthesurfacechargeslocatedintheexternalchannelvestibuleplayanimportantroleinmodulatingtoxinbinding.
CandiaS.,etal.Modeofactionofiberiotoxin,apotentblockerofthelargeconductanceCa(2+)-activatedK+channel.BiophysJ. PMID: 1384740
Smartox Biotechnolgy的多肽毒素产品如下：
1. 作用于钠离子通道(Sodium channel)的毒素
Toxin name | Catalog # | Target |
Phrixotoxin-3 | 13PHX003 | Selective blocker of Nav1.2 |
µ-conotoxin GIIIB | CON020 | Selective blocker of Nav1.4 |
µ-conotoxin CnIIIC | CON021 | Selective blocker of Nav1.4 |
μ-conotoxin PIIIA | 08CON006 | Selective blocker of Nav1.4 |
Jingzhaotoxin-III | 12JZH003 | Selective blocker of Nav1.5 |
ProTx-II | 07PTX002 | Selective blocker of Nav1.7 |
ProTx-II Biotin | 12PTB002 | Selective blocker of Nav1.7 |
ProTx-I | 12PTX001 | Blocker of Nav1.8, Nav1.2, Nav1.5, Nav1.7 |
Huwentoxin-I | 07HWT001 | Blocker of TTX-S |
Huwentoxin-IV | 08HWT002 | Blocker of TTX-S |
Hainantoxin-III | 13HTX003 | Blocker of TTX-S |
Hainantoxin-IV | 12HTX001 | Blocker of TTX-S |
GsAF-I | 12GSF001 | Blocker of TTX-S |
GsAF-II | 12GSF002 | Blocker of TTX-S |
2. 作用于钾离子通道(Potassium channel)的毒素
Toxin name | Catalog # | Target |
KCa channels | ||
Apamin 蜜蜂神经毒素 | 08APA001 | SK1, SK2, SK3 |
Charybdotoxin 蝎毒素 | 11CHA001 | KCa1.1, KCa3.1 - Kv1.2, Kv1.3, Kv1.6 |
Iberiotoxin | 12IBX001 | KCa1.1 |
Leiurotoxin 1 (Scyllatoxin) | 10LEI001 | SK1, SK2, SK3 |
Tamapin | 10TAM001 | SK1, SK2, SK3 |
Kaliotoxin-1 | 08KTX002 | BK, Kv1.1, Kv1.2, Kv1.3 |
Kv channels | ||
ShK | 08SHK001 | Kv1.3, Kv1.1, Kv1.4, Kv1.6 |
TMR-ShK | SAT001 | Kv1.3, Kv1.1 |
Margatoxin | 08MAG001 | Kv1.3 |
(Dap22)-ShK | 13SHD001 | Kv1.3 |
ADWX-1 | 13ADW001 | Kv1.3 |
HsTx1 | 08NEU001 | Kv1.3, Kv1.2 |
Agitoxin-2 | 13AGI002 | Kv1.3, Kv1.1 |
Maurotoxin | 08MAR001 | Kv1.2, KCa3.1 |
Guangxitoxin 1E | 11GUA002 | Kv2.1, Kv2.2 |
Stromatoxin 1 NEW | SCT01 | Kv2.1, Kv2.2 |
Kaliotoxin-1 | 08KTX002 | BK, Kv1.1, Kv1.2, Kv1.3 |
Charybdotoxin | 11CHA001 | KCa1.1, KCa3.1 - Kv1.2, Kv1.3, Kv1.6 |
Phrixotoxin-2 | PHX002 | Kv4.2, Kv4.3 |
AmmTx3 NEW | AMX001 | A-type potassium channels |
Inwardly rectifying potassium channels | ||
TertiapinQ | 08TER001 | Kir1.1, Kir3.1/3.4, Kir3.1/3.2-KCa1.1 |
hERG/Kv11.1 | ||
BeKm-1 | 13BEK001 | ERG1 |
3. 作用于钙离子通道(Calcium channel)的毒素
Toxin name | Catalog # | Target |
High voltage-gated Ca2+ channels | ||
ω-agatoxin IVA | 11AGA001 | P/Qtype |
ω-Conotoxin MVIIC | 08CON002 | P/Qtype, N-type |
ω-Conotoxin MVIIA | 08CON001 | N-type |
ω-Conotoxin GVIA | 08CON003 | N-type |
ω-Conotoxin SO3 | 08CON013 | N-type |
Huwentoxin I | 07HWT001 | N-type |
ProTx-II | 07PTX002 | T-type, L-type |
Intermediate voltage-gated Ca2+ channels | ||
SNX482 | 08SNX002 | R-type |
Low voltage-gated Ca2+ channels | ||
ProTx-I | 12PTX001 | T-type |
ProTx-II | 07PTX002 | T-type, L-type |
Ryanodine receptors | ||
Maurocalcine | 07PAU001 | Ryr1 |
4. 作用于氯离子通道(Chloride channel)的毒素
Toxin name | Catalog # | Target |
Chlorotoxin | 08CHL001 | Blocker of small conductance Cl- channels |
GaTx1 | 13GTX001 | Selective blocker of CFTR channel |
GaTx2 | 10GTX002 | Selective blocker of ClC-2 channel |
5. 作用于乙酰胆碱受体(Acetylcholine receptor)的毒素
Toxin name | Catalog # | Target |
α-conotoxin PeIA | 13CON017 | α9α10, α3β2 subunits |
α-Conotoxin PrXA | 13CON016 | α1/β1/ε/δ, α1/β1/γ/δ subunits |
Waglerin-1 | 12WAG001 | MusclenAChR |
α-conotoxin MI | 08CON012 | α1/δsubunits |
α-conotoxin GI | 08CON005 | α/δsite |
α-conotoxin IMI | 08CON011 | α7 homomeric nAChR |
α-conotoxin GID | CON019 | Blocker of α3β2, α7 and α4β2 nAChRs |
6. 含N-甲基-D-天冬氨酸NR2B
(NMDA, NR2B containing N-methyl-D-aspartate)
Conantokin-G
选择性、特异性抑制含NR2B的NMDAR。Conantokin-G能剂量依赖性抑制Ca2+内流，抑制NMDA诱导的兴奋性中毒效应。研究表明，在小鼠皮层神经元，Conantokin-G阻滞NMDA引发的电流信号的IC50值为480 nM。
7. 作用于酸敏感离子通道(ASIC channel, Acid-Sensing Ion Channel)的毒素
Toxin name | Catalog # | Target |
APETx2 | 07APE002 | Selective blocker of ASIC3 |
Psalmotoxin1/PcTx1 | 13PCT001 | Selective blocker of ASIC1a |
Ugr9-1 | 13UGR001 | Blocker of ASIC3 |
8. 作用于瞬时受体电位(TRP channel, transient receptor potential)的毒素
Toxin name | Catalog # | Target |
GsMTx4 | 08GSM001 | TRPC, TRPA |
Vanillotoxin3 | 10VAN003 | Activator of TRPV1 |
ProTx-I | 12PTX001 | Antagonist of TRPA1 |
9. 作用于嘌呤能通道(Purinergic channel)的毒素
Purotoxin-1
选择性抑制P2X3受体。100 nM Purotoxin-1 (PT-1)选择性抑制P2X3受体通道，在大鼠DRG神经元上，使用膜片钳实验表明：PT-1对电压门控通道和TRPV1均无抑制效应。10 µM ATP和100 µM α,β Methylene-ATP浓度下Purotoxin-1对P2X3受体有选择性作用，在该ATP浓度下Purotoxin-1对P2X2和杂化二聚体P2X2/3并无激动作用。Purotoxin-1对疼痛的潜在治疗作用。
10. 作用于其它膜受体通道(Others)的毒素
Smartox Biotechnology还提供其他类型的膜受体抑制剂：
Toxin name | Catalog # | Target |
Morphiceptin | 011CAS001 | Agonist of µ-opoid receptors |
Lys-conopressin G | 11CON14 | Vasopressin-like peptide |
GsMTx4 | 08GSM001 | Mechano sensitive ion channels |
Obtustatin | 10OBT001 | Blocks the binding of α1β1 integrin to collagen IV |
Rho-Conotoxin TIA | CON022 | Blocks α1-adrenergic receptor |
公司简介
Smartox Biotechnology是全球唯一一家专门生产动物毒液多肽毒素，用于细胞离子通道功能研究的生物医药公司。多肽毒素在生物制药领域具有重要的使用价值。
Smartox Biotechnology于2009年由来自Grenoble神经科学研究所(Grenoble Institute of Neuroscience)的Michel De Waard博士创立。Smartox Biotechnology专门研究动物毒液，制作合成多种毒液中的多肽成分（常称为毒素）。De Waard博士研究离子通道与毒素多肽的关系，尤其是鉴定、开发毒素多肽作为治疗性分子或细胞穿透肽(cell penetrating peptides, CPP)。其研究团队在毒液分离，药理性活性肽鉴定、富半胱氨酸肽定性、制作和优化等方面具有独特、丰富的经验。2010年，Smartox Biotechnolgy被法国研究部(Ministry of Research)授予“新兴企业OSEO奖(OSEO prize for emerging businesses)”。
总之，Smartox Biotechnolgy提供一系列高质量、具开创价值的多肽毒素。这些化合物在离子通道 研究中具有高的亲和性和选择性，是相应领域科学研究理想的生物毒素提供商和贴心的合作伙伴。
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