| Formulation | 50%glycerol/500uMEDTA(v/v) |
| Storage | -20°C |
| Purity | >95%bySDS-PAGE |
| ActivityDetermination | Photometricdetermination |
| ShelfLife(properlystored) | 12months |
TheconversionofsolublefibrintoaninsolublefibrinclotiscatalyzedbythetransamidasefactorXIIIa.Lysineandglutaminesidechainsofα-andγ-chainsoffibrinarecrosslinkedtoformhomopolymers.
SampleGelInformation:
| Gel | Novex4-12%Bis-Tris |
|---|---|
| Load | HumanFactorXIIIa,1µgperlane |
| Buffer | MOPS |
| Standard | SeeBluePlus2;Myosin(191kDa),PhosphorylaseB(97kDa),BSA(64kDa),GlutamicDehydrogenase(51kDa),AlcoholDehydrogenase(39kDa),CarbonicAnhydrase(28kDa),MyoglobinRed(19kDa),Lysozyme(14kDa) |
| SpecialNotes | Inthenon-reducedsampletheAchainshiftsdowntowardtheBchainfollowingactivation. |
Overview:
FactorXIIIa(FXIIIa)(fibrinoligase,plasmatransglutaminase,fibrinstabilizingfactor,E.C.2.3.2.13)isaglutaminyl-peptideγ-glutamyltransferasefunctioninginthefinalstagesofthecoagulationcascade,stabilizingthefibrinclotbycrosslinkingtheαandγchainsoffibrintoformhomopolymers(1-4).SeveraluniquefeaturesofFXIIIasetitapartfromproteinswithwhichitisgenerallyassociated.FactorXIIIaistheonlynon-proteolyticenzymeofthecoagulationcascade.Unlikeothertransamidases,itexiststotallyinzymogenicformandistheonlysulfhydrylaseenzymewhichfunctionsextracellularly.
PlasmaFXIIIaisatetramer,(Mr=312,000),composedof2pairsofnon-identicalsubunits(A2B2)(4-7).PlateletFXIIIisadimer(Mr=46,000),composedofonlyapairofidenticalAsubunits(A2)asisfactorXIIIfromallintracellularsources(7-11).TheAsubunitcontains6freesulfhydrylgroups,oneofwhichistheactivecenter(12).
TheconversionofplasmaFXIII(A2B2)totheactivetransglutaminase,FXIIIa(A2")resultsfromthethrombincatalyzedhydrolysisoftheArg36-Gly37peptidebondattheNH2-terminaloftheAsubunit(13).Theconformationalchangeinducedbythiscleavageresultsinexposureoftheactivesitecysteine.FullactivityisachievedonlyaftertheCa2+dependent(Kd=10-3M)dissociationoftheBsubunitdimerfromtheA2"dimer(14-16).DissociationoftheA2"B2complexisenhancedbybindingtotheregionoffibrin(ogen)containingresidues242-424oftheAachain(14-16).Thus,atnormalplasmaconcentrationsofFXIII(90nM),fibrinogen(8µM)andCa2+(2.5mMfree),alltheFXIIIageneratedwouldbeinthefullyactivated(A2")molecularform.OtherphysiologicallyrelevantcrosslinkedcomplexesgeneratedbyFXIIIaincludefibrin-fibrinogen(17),fibrin-fibronectin(18),fibrin-vWF(19),fibrin-α2-antiplasmin(20),fibrin-actin(21),fibrin-thrombospondin,fibronectin-collagen(19),vWF-collagen(19),actin-myosin(21,22),factorV-factorV(23).Inadditiontoclotstabilization,FXIIIaisthoughttofunctioninvariousprocessesinvolvingcellproliferation,suchaswoundhealing,tissueremodeling,atherosclerosis,andtumorgrowth.
PlasmaFXIIIaisgeneratedbycleavageofhomogenousplasmaFXIIIbyalpha-thrombin,inthepresenceofEDTA.TheA2"B2subunitispurifiedbyionandaffinitychromatographyandsuppliedin50%glycerol,0.5mMEDTAforstorageat-20°C.
Properties:
| Localization | Plasma | |||||
|---|---|---|---|---|---|---|
| Modeofaction | Plasmatransglutaminase | |||||
| Molecularweight | 312,000(4) | |||||
| Extinctioncoefficient |
| |||||
| Isoelectricpoint | 5.2(inferredfromthezymogen,factorXIII) | |||||
| Structure | tetramer(A2"B2)intheabsenceofcalcium,twoidenticalAchains(Mr=71,000)eachcontaining6freesulfhydrylsandandactivesite,twoidenticalBsubunit(Mr=88,000)identicalsubunits,A(Mr=75,000),B(Mr=88,000)/td> | |||||
| CarbohydrateContent | Achain:1% Bchain:5% |
