| Formulation | 50%(vol/vol)Glycerol/H2O |
| MolecularWeight | |
| Storage | -20°C |
| Purity | >95%bySDS-PAGE |
| Compound | |
| Assay | Thrombininhibition |
| ShelfLife(properlystored) | 12months |
| ChemicalFormula | |
Thrombin(IIa),heparin(HEP)andheparincofactorII(HCII)interacttoformaternarycomplexviaarandomorderbireactantmechanism.HeparinsubsequentlydissociatesfromthecomplexasthrombinformsacovalentcomplexwiththeheparincofactorII.
SampleGelInformation:
| Gel | Novex4-12%Bis-Tris |
|---|---|
| Load | HumanHeparinCofactorII,1µgperlane |
| Buffer | MOPS |
| Standard | SeeBluePlus2;Myosin(191kDa),PhosphorylaseB(97kDa),BSA(64kDa),GlutamicDehydrogenase(51kDa),AlcoholDehydrogenase(39kDa),CarbonicAnhydrase(28kDa),MyoglobinRed(19kDa),Lysozyme(14kDa) |
Overview:
HeparincofactorII(HCII)(heparincofactorA,antithrombinBM,dermatansulfatecofactor,humanleuserpin-2)isasinglechainglycoprotein(Mr=65,600,10%carbohydrate)memberoftheserineproteaseinhibitor(serpin)family(1-3).AminoacidsequenceanalysisofheparincofactorIIreveals3potentialN-glycosylationsitesand2sulfatedtyrosineslocatedintwointernalrepeatsof7residueslocatedneartheNH2-terminal(4-6).Theplasmaconcentrationisestimatedtobe90µg/ml(2).
Inthecoagulationcascade,heparincofactorIIinhibitsthrombinbyformationofabimolecularcomplexinthepresence(k2=4.5x108M-1min-1)andabsence(k2=5.0x105M-1min-1)ofheparin(2,7-9).ThiscomplexisstabletodenaturantsandessentiallyirreversIBLe.Inadditiontoheparin,awidevarietyofpolyanioniccompoundsaccelerateinhibitionofthrombinbyHCII(3).Noteworthyamongthesecompoundsisdermatansulfate,whichacceleratesinhibitionofthrombinbyHCII,butnotantithrombinIII(1,6)ThisfeaturehasbeenutilizedtodevelopaplasmabasedassayspecificforheparincofactorII.AlthoughHCIIshowsonly~25%sequencehomologytootherserpins,thereactivesitepeptide(COOH-terminal36aminoacids)releasedoninhibitionofthrombinis53%homologoustothatreleasedfromantithrombinIII(ATIII)bythrombin(4,9).ThescissilebondinHCIIisLeu-Serwhichisunusualforanargininespecificproteaseinhibitor(4,9).IncontrasttoATIII,theonlycoagulationproteaseinhibitedbyHCIIisthrombin,OtherproteasesinhibitedbyHCIIincludeα-chymotrypsin,neutrophilcathepsinGandstreptomycesgriseusproteaseB(3).ThemajorphysiologicroleofheparincofactorIImayremaintobediscovered.
HeparincofactorIIispreparedfromfreshfrozenplasmabyamodificationoftheprocedureofGriffith,etal.,(9).PurityisassessedonSDSPAGEandactivityisdeterminedbasedonthrombininhibitioninthepresenceofdermatansulfate.HCIIissuppliedin50%(vol/vol)glycerol/H20forstorageat-20°C.
Properties:
| Localization | Plasma | |||||
|---|---|---|---|---|---|---|
| Plasmaconcentration | 90µg/ml(2) | |||||
| Modeofaction | serineproteaseinhibitor;inhibitsthrombin,a-chymotrypsin,neutrophilcathepsinG,streptomycesgriseusproteaseB | |||||
| Molecularweight | 65,600(2) | |||||
| Extinctioncoefficient |
| |||||
| Isoelectricpoint | 4.95-5.15(2) | |||||
| Structure | singlechainglycoprotein,3potentialN-glycosylationsites,two7-aminoacidresiduerepeats,reactivesitesequence:TVTTVGFMPL-STQVRFTVDR(4) | |||||
| Percentcarbohydrate | 9.9%(2) | |||||
| Post-translationalmodifications | 3sulfatedtyrosines |
