| Formulation | 50%(vol/vol)glycerol/500uMEDTA |
| Storage | -20°C |
| Purity | >95%bySDS-PAGE |
| ActivityDetermination | CommercialXIIIELISA |
| ShelfLife(properlystored) | 12months |
Thezymogen,factorXIII,isatetramer(A2B2)composedof2identicalAsubunitsand2identicalBsubunits.ThrombincleavesaMr=4000peptidefromtheNH2-terminalofthelightchain,exposingtheactivesitesulfhydryl.FullexpressionofactivityisachievedfollowingCa2+-dependentdissociationoftheBchaindimer.
SampleGelInformation:
| Gel | Novex4-12%Bis-Tris |
|---|---|
| Load | HumanFactorXIII,1µgperlane |
| Buffer | MOPS |
| Standard | SeeBluePlus2;Myosin(191kDa),PhosphorylaseB(97kDa),BSA(64kDa),GlutamicDehydrogenase(51kDa),AlcoholDehydrogenase(39kDa),CarbonicAnhydrase(28kDa),MyoglobinRed(19kDa),Lysozyme(14kDa) |
Overview:
FactorXIIIisthezymogenicformoftheglutaminyl-peptideg-glutamyltransferasefactorXIIIa(fibrinoligase,plasmatransglutaminase,fibrinstABIlizingfactor,E.C.2.3.2.13)(1-3).FactorXIIIisuniqueamongtransamidasesinthatitisazymogeninvivo(2).FactorXIIIisfoundbothextracellularlyinplasmaandintracellularlyinplatelets,megakaryocytes,monocytes,placenta,uterus,liverandprostratetissues.PlasmafactorXIIIissynthesizedintheliverandcirculatesasatetramer(Mr=320,000),composedof2pairsofnonidenticalsubunits(A2B2)(4).Theintra-cellularformsaresynthesizedinthetissueswheretheyresideasdimers(Mr=146,000)of2identicalAchains(A2)(7-11).TheAsubunitsofplasmaandintracellularformsoffactorXIIIarefunctionallyidentical.TheAsubunitcontains6freesulfhydrylgroupsoneofwhichistheactivesite(12).
TheconcentrationoffactorXIIIinplasma(A2B2)isapproximately30mg/ml(8).Itisthelastofthezymogenstobecomeactivatedinthecoagulationcascadeanditistheonlyenzymeinthissystemthatisnotaserineprotease.TheconversionofplasmafactorXIII(A2B2)totheactivetransamidasefactorXIIIa(A2")resultsfromhydrolysisoftheArg36-Gly37attheNH2-terminusoftheAsubunitbythrombin(13).FullexpressionofactivityisachievedonlyaftertheCa2+(Kd=10-3M)andfibrin(ogen)(Kd=10-8M)dependentdissociationoftheBsubunitdimerfromtheA2"dimer(14-16).
Inthecoagulationcascade,factorXIIIafunctionstostabilizethefibrinclotbycrosslinkingtheaandg-chainsoffibrin.OtherproteinsknowntobesubstratesforFactorXIIIawhichmaybehemostaticallyimportantincludefibronectin(17),α2-antiplasmin(18),collagen(19),factorV(20),vonWillebrandFactor(19)andthrombospondin(21,22).
FactorXIIIispurifiedfromfreshfrozenhumanplasmabyamodificationoftheproceduresdescribedbyFolke(2)andLorand(10)involvingbariumcitrate,ammoniumsulfateandglycineprecipitations,ionexchangechromatographyandgelfiltration.FactorXIIIishomogeneousasjudgedbySDSPAGE,withaspecificactivityof~50units/mg.FactorXIIIissuppliedin50%glycerolcontaining0.5mMEDTA,forstorageat-20oC.
Properties:
| Localization | Plasma | |||||
|---|---|---|---|---|---|---|
| Plasmaconcentration | 30µg/ml(3) | |||||
| Modeofaction | Zymogen;precursortothetransglutaminase,factorXIIIa | |||||
| Molecularweight | 320,000(4) | |||||
| Extinctioncoefficient |
| |||||
| Isoelectricpoint | 5.2 | |||||
| Structure | tetramer(A2B2)ofnoncovalentlyassociatedpairsof2nonidenticalsubunits,A(Mr=75,000),B(Mr=88,000);theAsubunithas6freesulfhydrylsandthepotentialactivesite | |||||
| CarbohydrateContent | Achain:1%(22) Bchain:5%(22) |
