Alpha 2-antiplasmin's carboxy-terminal lysine residue is a major site of interaction with plasmin.
alpha 2-Antiplasmin (AP) inhibits plasmin in a two-step reaction in which AP reversibly binds to lysine-binding sites of plasmin and, then, more slowly complexes covalently with the enzyme's active site. Here, we show that the C-terminal lysine residue of AP has a key role in binding of the inhibitor to plasmin. A synthetic peptide corresponding to the C-terminal 26 amino acid residues of AP blocked association of AP with plasmin, but this activity of the peptide was lost when its C-terminal lysine residue was removed with carboxypeptidase B. The essential role of this lysine residue was shown more directly by treating AP with carboxypeptidase B and observing that AP lost its ability to inhibit plasmin rapidly.
Hortin
G L
GL
Department of Pediatrics, Washington University, St. Louis, MO 63110.
Gibson
B L
BL
Fok
K F
KF
D001665:Binding Sites; D002851:Chromatography, High Pressure Liquid; D005341:Fibrinolysin / Q000378:metabolism*; D008239:Lysine / Q000032:analysis*; D000979:alpha-2-Antiplasmin / Q000032:analysis* / Q000378:metabolism
D000979:alpha-2-Antiplasmin; D005341:Fibrinolysin; D008239:Lysine