Amino acid sequences of plasmin digests of β₂GPI and r-Domain V. Each value under the amino acid sequence identified shows the amount of PTH-amino acid (in picomoles) recovered using a gas-phase sequencer. Any other sequence was not observed: (1), plasmin digest of r-Domain V; (2), C-terminal peptide of plasmin-treated r-Domain V (see Fig 3); (3), Peak 1 from plasmin-treated β₂GPI (see Fig 4A); (4), peak A of β₂GPI from acid-treated and UK-activated plasma (see Fig7); (5), peak B of β₂GPI from acid-treated and UK-activated plasma; (6), intact β₂GPI; and (7), intact r-Domain V.