Ranking reactive glutamines in the fibrinogen αC region that are targeted by blood coagulant factor XIII

摘要: Factor XIIIa (FXIIIa) introduces covalent γ-glutamyl-e-lysyl crosslinks into the blood clot network. These involve both γ and α chains of fibrin. The C-terminal portion fibrin chain extends αC region (210-610). Crosslinks within this help generate a stiffer clot, which is more resistant to fibrinolysis. Fibrinogen (233-425) contains binding site for FXIIIa three glutamines Q237, Q328, Q366 that each participate in physiological crosslinking reactions. Although these were previously identified, their reactivities toward have not been ranked. Matrix-assisted laser desorption/ionization time flight (MALDI-TOF) mass spectrometry nuclear magnetic resonance (NMR) methods thus used directly characterize probe sources substrate specificity. Glycine ethyl ester (GEE) ammonium chloride served as replacements lysine. Mass 2D heteronuclear single quantum coherence NMR revealed Q237 rapidly crosslinked first by followed Q328. Both (15)NH4Cl (15)N-GEE could be with similar order reactivity observed MALDI-TOF assay. studies using mutants Q237N, Q328N, Q366N demonstrated no glutamine dependent on another react series. Moreover, remaining two mutant still reactive. Further characterization important because they are located fibrinogen susceptible truncations mutation. current results suggest play distinct roles architecture.