Formulation | Lyophilizedfrom20mMNaCit,20mMNaPO4,pH7.3 |
Storage | 4°C |
Purity | >95%bySDS-PAGE |
ActivityDetermination | N/A |
ShelfLife(properlystored) | 12months |
Gel | Novex4-12%Bis-Tris |
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Load | 1µgperlane;purifiedhumanfibrinogen |
Buffer | MOPS |
Standard | SeeBluePlus2;Myosin(191kDa),PhosphorylaseB(97kDa),BSA(64kDa),GlutamicDehydrogenase(51kDa),AlcoholDehydrogenase(39kDa),CarbonicAnhydrase(28kDa),MyoglobinRed(19kDa),Lysozyme(14kDa) |
Thethrombin(IIa)catalyzedcleavageofsolublefibrinogen(Fbg)toformfibrin(Fbn)istheterminalproteolyticeventinthecoagulationcascade.ThesesolubleFbnmonomersspontaneouslypolymerizetoformaninsolubleFbnnetworkwhichisstABIlizedbythefactorXIIIacatalyzedcrosslinkingoflysandgluresiduesofαandγchains.ThisFbnnetworkisthemajorproteincomponentofthehemostaticplug.
Plasmafibrinogenislargeglycoprotein(Mr=340,000)synthesizedintheliverandcirculatingataconcentrationof2.6mg/ml.Itisadisulfidelinkeddimercomposedof3pairsofdisulfidelinkednon-identicalpolypeptidechains(Aα,Bβandγ).NotablefeaturesoftheAαchainaretheN-terminalpeptide(fibrinopeptideA(FPA,1-16)),factorXIIIacrosslinkingsitesand2phosphorylationsites.Whensynthesized,Fbgisfullyphosphorylated,butcirculatesatonly20-30%phosphorylation.TheBβchaincontainsfibrinopeptideB(FPB,1-14),oneofthe3N-linkedcarbohydratemoieties(Mr=2500)andanN-terminalpyroglutamicacid.TheγchaincontainstheotherN-linkedglycosylationsiteandafactorXIIIacrosslinkingsites.The2elongatedsubunits((AαBβγ)2)arealignedinanantiparallelmannerformingatrinodulararrangementofthesixchains.Thenodesareformedbydisulfideringsbetweenthe3parallelchains.Thecentralnode(n-disulfideknot,Edomain)isformedbytheN-terminiofallsixchainsheldtogetherby11disulfidebonds.Thisregioncontainsthe2IIa-sensitivesites.ThereleaseofFPAbycleavageatR16-G17generatesFbnI,exposingapolymerizationsite(17-20)ontheAαchain.TheseregionsbindtocomplimentaryregionsontheDdomainofFbntoformprotofibrils.SubsequentIIacleavageofFPB(R14-G15)fromtheBβchainexposesadditionalpolymerizationsitesandpromoteslateralgrowthoftheFbnnetwork.
Eachofthe2domainsbetweenthecentralnode(Edomain)andtheC-terminalnodes(Ddomain)iscomposedofparallelα-helicalregionsoftheAα,Bβandγchainscoiledaroundeachothertoforma"coiledcoil"withpolarresiduesdirectedoutwardandnonpolarresiduesformingahydrophobiccore.Inthisregion,all3chainspossessaprotease(plasmin)sensitivesite.Theothermajorplasminsensitivesiteisinthehydrophilicpreturbanceoftheα-chainfromtheC-terminalnode.ControlledplasmindegradationatthesesitesconvertsFbgintofragmentDandfragmentE.Theindividualfragmentsareisolatedbysaltfractionation,gelfiltrationandionexchangechromatography.Thefragmentsaresuppliedlyophilizedforstorageat4°C.Highlypurifiedresearchgradefibrinogen(>95%clottable)ispreparedbyacombinationofconventionalandaffinitytechniques.Itissuppliedasafrozensolutioninctirate-phosphateforstorageat-80°C.
Localization | Plasma,platelets | |||||
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Plasmaconcentration | 2.6mg/ml | |||||
Modeofaction | Precursormoleculewhichiscleavedbythrombintoformfibrinclot. | |||||
Molecularweight | 340,000 | |||||
Extinctioncoefficient |
| |||||
Isoelectricpoint | 5.1-6.3 | |||||
Structure | Dimerof3pairsofnon-identicalchainsAα(Mr=66,800),Bβ(Mr=52,000)andγ(Mr=46,500),Elongatedtrinodularmoleculewith2terminalDdomainsandonecentralEdomain.FactorXIIIacross-linkingsitesatE328,E366,K508,K584inAαchain;atE398andK406inBβchain. | |||||
Percentcarbohydrate | 3% | |||||
Post-translationalmodifications | Aαchain:2phosphorylatedserines,S3,S346 Bβchain:N364glycosylationsiteMr=2500,N-terminalpyroglutamicacid γchain:glycosylatedN52 |
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