Description:
ChromogenixS-2222™isachromogenicsubstrateforFactorXa.Itisalsoverysensitivetotrypsin.Thesubstratehasbeenusedforthedeterminationof:
- FactorXinplasma
- FactorXainplasma
- FactorXainhibitorinplasma
- Heparininplasma
- FactorVIIIinplasma
- Coagulatingenzymefromhorseshoecrabplasma
- Trypsininduodenalfluid
Thesubstrateisalsosensitivetosubtilisin,acrosinandFactorXIIabutinsensitivetomostotherenzymestested,e.g.FactorIXa,kallikrein(glandularandplasma)andpapain-likeenzymes.
Composition:
EachvialcontainschromogenicsubstrateS-2222™25mgandmannitol120mgasabulkingagent.
Molecularwt:741.3
Formula:Bz-Ile-Glu(g-OR)-Gly-Arg-pNA·HClR=H(50%)andR=CH3(50%)
Chemicalname:N-Benzoyl-L-isoleucyl-L-glutamyl-glycyl-Larginine-p-nitroanilinehydrochlorideanditsmethylester
FactorXaIUandEnzymeActivity:
FactorXa,whichhasamolecularweightof44KDa,istheactivatedformofFactorX(MW:59KDa).
TheInternationalUnitsofFactorXcorrespondtotheamountofFactorXcontainedin1mlofnormalplasma.Thisisabout8mg/lor0.13µmol/l.
SincethereisnoWHOstandardforFXa,onewouldassumethatifalltheFactorXinnormalplasmawasconvertedtotheactivatedform,theFactorXaconcentrationwouldbeapproximately5.7mg/l.
TheactivityofhumanFactorXaascalculatedfromthekinetictablesis1.5nkat/µgwiththechromogenicsubstrateS-2222™,and4.4µkat/µgwiththechromogenicsubstrateS-2765™.
Theactivityof1µgofFactorXaasdeterminedbyFrieberger(1)is1.9nkatchromogenicsubstrateS-2222™.
Thus,1plasmaequivalentunitofFactorXwouldcorrespondto15.2nkatchromogenicsubstrateS-2222™.
FribergerPetal.
Syntheticpeptidesubstrateassaysandfibrinolysisandtheirapplicationonautomates.In:SeminarsinThrombosisandHaemostasis,Vol.9,281-300(1983).
