Hortin G L, Gibson B L, Fok K F
Department of Pediatrics, Washington University, St. Louis, MO 63110.
Biochem Biophys Res Commun. 1988 Sep 15;155(2):591-6. doi: 10.1016/s0006-291x(88)80535-7.
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.
