| Formulation | Lyophilizedfrom0.2MGlycine,150mMNaCl,pH7.4 |
| Storage | 4°C |
| Purity | >95%bySDS-PAGE |
| ActivityDetermination | Plasmaequivalencyunits |
| ShelfLife(properlystored) | 12months |
ThefivecontiguousSushidomains(I-V)ofβ2Iareshown.The5carbohydratesidechainsatN73,N143,N164,N174,andN224arerepresented(CHO).
SampleGelInformation:
| Gel | Novex4-12%Bis-Tris |
|---|---|
| Load | HumanBeta-2Glycoprotein1,1µgperlane |
| Buffer | MOPS |
| Standard | SeeBluePlus2;Myosin(191kDa),PhosphorylaseB(97kDa),BSA(64kDa),GlutamicDehydrogenase(51kDa),AlcoholDehydrogenase(39kDa),CarbonicAnhydrase(28kDa),MyoglobinRed(19kDa),Lysozyme(14kDa) |
Overview:
β2-GlycoproteinI(β2I,ApolipoproteinH)isahighlyglycosylatedsinglechainprotein(Mr=54,200)whichissynthesizedintheliverandcirculatesinplasmaataconcentrationof100-200µg/ml(1-4).Approximately40%oftheplasmaβ2Iisassociatedwithlipoproteins,whichledtothedesignationapolipoproteinH(5).The326aminoacidproteincontainsfiverepeatingmutuallyhomologousdomainsconsistingofapproximately60aminoacidswhicharedisulfidebondedtoformShortConsensusRepeats(SCR)orSushidomains.Thethird,C-terminalsushidomaincontainsthreeofthefiveN-linkedcarbohydratechains,atpositionsN143,N164,N174.TheothertwositesareatN73andN234indomainsIIandIV,respectively.Thereare38basicaminoacidresiduesdistributedunevenlyamongthefivedomains;eightindomainI,fiveindomainII,fiveindomainIII,fiveindomainIVandfifteenindomainV.ThedirectbindingofdomainsIandVhasbeendemonstratedandlikelyresultsfromfoldingofthemoleculeinamannerthatexpressesanetcationicsurfacecharge(5).
Althoughthephysiologicalroleofβ2Iisstillbeingstudied,theABIlitytobindtoanionicsurfaceshasbeenthefocusofintenseinvestigation.β2Ihasbeenshowntobindtoanionicvesicles(3),platelets(6),DNA(7),mitochondria(8)andheparin(9).Ithasbeensuggestedthatthebindingofβ2Itonegativelychargedsurfacescaninhibitthecontactactivationpathwayinbloodcoagulation.Thebindingtoactivatedplateletsisreportedtoinhibitplateletassociatedprothrombinaseandadenylatecyclaseactivities.StudiesonphysiologicrolesforbindingtoDNA,mitochondria,heparanoidsandphospholipidshavefocusedontheareaofautoimmunedisorders.Inparticular,thecomplexesbetweenβ2Iandcardiolipinhavebeenimplicatedintheanti-phospholipidrelateddisordersLACandSLE(10-13).
Thehumanβ2-GlycoproteinIispurifiedfromfreshfrozenhumanplasma,usingacombinationofionexchangeandaffinitychromatography.Inadditionitispurifiedoverananti-humanfactorXIcolumntoremoveanypotentialcontaminentsofXI/XIa.Itisgreaterthan95%purebySDSPAGE.Thehumanβ2-GlycoproteinIislyophilizedfromaglycine-NaClbufferandshouldbestoredat4°C.
Properties:
| Localization | Plasma | |||||
|---|---|---|---|---|---|---|
| PlasmaConcentration | 100-200µg/ml | |||||
| Modeofaction | CationicresiduesonthesurfaceofsushidomainsIandVbindtoanionicphospholipids.Inhibitionofcontactactivation,plateletmembranedependantprothrombinaseandadenylatecyclaseactivities.ComplexeswithDNA,mitochondria,andcardiolipinaugmentsantigenicityinautoimmunedisorders. | |||||
| Molecularweight | 54,200(SDSPAGE),48,000(Sed.Equil) | |||||
| Extinctioncoefficient |
| |||||
| Structure | 326aminoacidsinglechainproteinwith5contiguousShortConsensusRepeatsonsushidomains. | |||||
| Percentcarbohydrate | 25% | |||||
| Post-translationalmodifications | 5N-linkedglycosylationsites,1indomainII(N73),3indomainIII(N143,N164,N174)and1indomainIV(N224). |
