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Crosslinking of α 2 ‐Antiplasmin to Fibrin
Author(s) -
LEE KYUNG N.,
LEE CHUNG S.,
TAE WEONCHAN,
JACKSON KENNETH W.,
CHRISTIANSEN VICTORIA J.,
MCKEE PATRICK A.
Publication year - 2001
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1111/j.1749-6632.2001.tb03520.x
Subject(s) - chemistry , fibrin , alpha (finance) , fibrinolysis , biochemistry , plasmin , biology , enzyme , immunology , medicine , psychology , construct validity , nursing , psychiatry , patient satisfaction
A bstract : Human α 2 ‐antiplasmin (α 2 AP) is the primary inhibitor of plasmin‐mediated fibrinolysis and is an efficient substrate of activated factor XIII (FXI‐IIa). Among 452 amino acid residues in α 2 AP, Gln 2 is believed to be the sole FXI‐IIa‐reactive site that participates in crosslinking α 2 AP to fibrin. We studied the effect of mutating Gln 2 on the ability of FXIIIa to catalyze crosslinking of α 2 AP to fibrin. By FXIIIa catalysis, [ 14 C]methylamine was incorporated into a Q2A‐α 2 AP mutant in which Gln 2 (Q) was replaced by Ala (A), thereby indicating that wildtype α 2 AP has more than one FXIIIa‐reactive site. To identify the FXIIIa‐reactive sites in α 2 AP, wildtype α 2 AP and Q2A‐α 2 AP were labeled with 5‐(biotinamido)pentylamine by FXIIIa. Each labeled α 2 AP was digested with trypsin and applied to an avidin affinity column to capture labeled peptides. Edman sequencing and mass analysis of each labeled peptide showed that out of 35 Gln residues in wildtype α 2 AP, four were labeled with the following order of efficiency: Gln 2 > Gln 21 > Gln 419 > Gln 447 . Q2A‐α 2 AP was also labeled at the three minor sites, Gln 21 > Gln 419 > Gln 447 . Q2A‐α 2 AP became crosslinked to fibirin(ogen) by FXIIIa catalysis at approximately one‐tenth the rate of wt‐α 2 AP. These results demonstrate that α 2 AP has one primary (Gln 2 ) and three minor substrate sites for FXIIIa and that the three minor sites identified in this study can also participate in crosslink formation between α 2 AP and fibrin, but at a much lower efficiency than the Gln 2 site.