Table 2.
Inhibition of activated factor XII (α‐FXIIa) by synthetic peptides based on the central inhibition loop of corn trypsin inhibitor (CTI). Concentrations of inhibitory peptide between 10−6 m and 10−3 m were incubated with substrate peptide, and this was followed by addition of α‐FXIIa. The initial rate of substrate conversion was determined by following the release of pNA colorimetrically. Data were analyzed by non‐linear regression in graphpad prism 6.04 with the log[inhibitor] versus response – variable slope algorithm with a bottom constraint. pIC50 values are indicated with the standard error (SE) of the fit (n = 3–5 independent experiments). For reference, the corresponding IC50 is also given, as is the fold reduction in inhibitory activity of each mutant as compared with inhibition by recombinant CTI (rec‐CTI)
| Peptide | pIC50 ± SE | IC50 (m) | Fold |
|---|---|---|---|
| rec‐CTI (full‐length reference) | 6.94 ± 0.05 | 1.2 × 10−7 | 1 |
| CTI(20–44): CRWYVTSRTAGIGPRLPWPELKRRC | 3.54 ± 0.15 | 2.9 × 10−4 | 2416 |
| CTI(21–43): RWYVTSRTAGIGPRLPWPELKRR | 3.34 ± 0.15 | 4.6 × 10−4 | 3833 |
| CTI(23–43): YVTSRTAGIGPRLPWPELKRR | 2.94 ± 0.05 | 1.1 × 10−3 | 9166 |
| CTI(21–42): RWYVTSRTAGIGPRLPWPELKR | 3.70 ± 0.04 | 2.0 × 10−4 | 1667 |
| CTI(31–38): IGPRLPWP | NIA | NIA | – |
| Scrambled: GISTAGPWRRRPPELLKVTY | NIA | NIA | – |
NIA, no inhibitory activity was observed.