Human inter-α-inhibitor is a substrate for factor XIIIa and tissue transglutaminase

Carsten Scavenius Sonne-Schmidt, Kristian Wejse Sanggaard, Camilla Lund Nikolajsen, Steffen Bak, Zuzana Valnickova, Ida Thøgersen, Ole N Jensen, Peter Højrup, Jan J. Enghild

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In this study, we show that inter-α-inhibitor is a substrate for both factor XIIIa and tissue transglutaminase. These enzymes catalyze the incorporation of dansylcadaverine and biotin-pentylamine, revealing that inter-α-inhibitor contains reactive Gln residues within all three subunits. These findings suggest that transglutaminases catalyze the covalent conjugation of inter-α-inhibitor to other proteins. This was demonstrated by the cross-linking between inter-α-inhibitor and fibrinogen by either factor XIIIa or tissue transglutaminase. Finally, using quantitative mass spectrometry, we show that inter-α-inhibitor is cross-linked to the fibrin clot in a 1:20 ratio relative to the known factor XIIIa substrate α2-antiplasmin. This interaction may protect fibrin or other Lys-donating proteins from adventitious proteolysis by increasing the local concentration of bikunin. In addition, the reaction may influence the TSG-6/heavy Chain 2-mediated transfer of heavy chains observed during inflammation.
TidsskriftBBA General Subjects
Udgave nummer12
Sider (fra-til)1624-1630
StatusUdgivet - 2011


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