| Formulation | 50%glycerol/water(v/v) |
| Storage | -20°C |
| Purity | >95%bySDS-PAGE |
| ActivityDetermination | Clottingassay |
| ShelfLife(properlystored) | 12months |
ThedomainstructureofthefactorXImonomerisrepresented.TheareasidentifiedasR1throughR4correspondtofourtandemaminoacidsequencerepeatswhichultimatelycomprisetheheavychainoffactorXIa.DuringproteolyticactivationbyfactorXIIa,the"CATALYTICDOMAIN",whichcomprisesthelightchainoffactorXIa,iscleavedfromtheheavychainregion.TheheavyandlightchainsoffactorXIaremainassociatedthroughadisulfidebond.ThematurefactorXImoleculeisahomodimercomposedoftwoapparentlyidenticalmonomerswhichremainassociatedthroughdisulfidebonds.
SampleGelInformation:
| Gel | Novex4-12%Bis-Tris |
|---|---|
| Load | HumanFactorXI,1µgperlane |
| Buffer | MOPS |
| Standard | SeeBluePlus2;Myosin(191kDa),PhosphorylaseB(97kDa),BSA(64kDa),GlutamicDehydrogenase(51kDa),AlcoholDehydrogenase(39kDa),CarbonicAnhydrase(28kDa),MyoglobinRed(19kDa),Lysozyme(14kDa) |
| SpecialNotes | Heavychainisadoubletduetothepresenceofupto50%betaform.Theconversionofalpha-Xatobeta-Xaoccursbyautocleavageofalpha-Xabyalpha-XaresultinginthelossofaCOOH-terminalpeptide. |
Overview:
FactorXIisaplasmaglycoproteinwhichcirculatesinanon-covalentcomplexwithhighmolecularweightkininogen(1).Thematuremoleculeissynthesizedintheliverandisatwo-chainhomodimerwithamolecularweightofapproximately160,000(2,3).Itisestimatedthat5%ofthetotalmassisattributabletocarbohydrate(2).Thetwoidenticalmonomershavemolecularweightsof80,000,andarejoinedtogetherbydisulfidebonds.ThusbySDS-PAGEanalysis,factorXIappearsasasinglebandbothnon-reduced(Mr=160,000),andreduced(Mr=80,000).
FactorXIcirculatesasazymogenandrequiresproteolyticactivationtoacquireserineproteaseactivity.TheconversionoffactorXItofactorXIaiscatalyzedbyfactorXIIa,andresultsincleavageoftheArg369-Ile370bondineachmonomer(3).FactorXIaconsistsoftwoNH2-terminalderivedheavychains,andtwoCOOH-terminalderivedlightchains,allofwhichareheldtogetherbydisulfidebonds.FactorXIaparticipateswithintheintrinsicpathwayofcoagulationbycatalyzingtheconversionoffactorIXtofactorIXa.AbleedingdisordercalledplasmathromboplastinantecedentdeficiencyresultsfromalackoffactorXIprocoagulantactivity(4,5).ThevariablebleedingtendenciesobservedinfactorXIdeficientpatientsdonotcorrelatewitheitherfactorXIactivityorantigenlevels.ThislatterobservationmayberelatedtotheABIlityofthetissuefactor/factorVIIacomplextoalsoactivatefactorIXtoIXa.
Historically,factorXIhasbeendifficulttopurifyduetoitsrelativelylowconcentrationinplasma,anditssusceptibilitytoproteolysis(6).FactorXIispurifiedfromfreshfrozenplasmathatisstabilizedbyaddedinhibitors.TheplasmaisfirsttreatedwithBaCl2toremovethevitaminK-dependentproteins,andfactorXIisthenisolatedbyaffinitychromatography.AfinalchromatographysteponheparinsepharoseyieldsahomogeneouspreparationofintactfactorXI.Thefinishedproductissuppliedin50%(vol/vol)glycerol/H2Oandshouldbestoredat-20oC.
Properties:
| Localization | Plasma;inassociationwithhighmolecularweightkininogen | |||||
|---|---|---|---|---|---|---|
| Plasmaconcentration | 2-7µg/ml(2,3,7,8) | |||||
| Modeofaction | Zymogen;precursortotheserineproteasefactorXIa | |||||
| Molecularweight | 160,000(human)(2,3) | |||||
| Extinctioncoefficient |
| |||||
| Isoelectricpoint | 8.9-9.1 | |||||
| Structure | homodimerconsistingoftwoapparentlyidenticalsubunits(Mr~80,000)heldtogetherbydisulfidebonds.Monomerscontainfourtandemaminoacidrepeatsthatsharehomologywithplasmaprekallikrein(9). | |||||
| Percentcarbohydrate | 5%(human)(2) |
