(C) GSK716 binds to Z α1-antitrypsin with a high affinity mean pKD of 8.5 ± 0.12 (n = 18) as determined by a competition binding assay with a fluorescently labelled derivative. There was a 50-fold lower affinity for plasma-purified wild-type M α1-antitrypsin, with a mean pKD of 6.8 ± 0.18 (n = 10). Data presented as mean ± SD. 