Table 1.
Serine proteinase inhibitory (SPI) activities of the Bikunin Kunitz protease inhibitor (KPI) domains and bovine pancreatic trypsin inhibitor (BPTI).
| Proteinase | Substrate * | Mean Relative Inhibitory Activity by 1 Unit of SPI ** (% Inhibition) ± SD (n = 6) | ||
|---|---|---|---|---|
| Sheep Kunitz Domain 1 | Sheep Kunitz Domain 2 | BPTI | ||
| Porcine pancreatic trypsin | ZAPNA | 95 ± 2.61 | 97 ± 1.47 | 96 ± 3.54 |
| Porcine Pancreatic chymotrypsin | AAVANA | 52 ± 4.05 | 55 ± 2.86 | 53 ± 3.73 |
| Human Leucocyte elastase | SAAVNA | 67 ± 4.79 | 69 ± 3.06 | 78 ± 4.07 |
| Human Leucocyte cathepsin G | SAAPPNA | 18 ± 7.09 | 25 ± 5.01 | 28 ± 4.03 |
| Porcine Kallikrein | VLANA | 55 ± 8.84 | 86 ± 4.41 | 92 ± 5.68 |
| Porcine Plasmin | VLLNA | 51 ±4.84 | 85 ± 1.94 | 88 ± 8.84 |
** One unit of inhibitory activity was defined as the amount of SPI required to give 50% inhibition of 0.2 μg of active site titrated trypsin. Each proteinase (0.2 µg) was incubated with one unit of SPI and residual enzyme activity assessed relative to enzyme samples incubated in the absence of inhibitor using the indicated substrates. * Abbreviations: ZAPNA: CBZ-Arg-4 NA; AAVANA: Ala-Ala-Val-Ala 4-NA; SAAVNA: N-Succinyl-Ala-Ala-Val-4NA, SAAPPNA: N-Succinyl-Ala-Ala-Pro-Phe 4-NA; VLANA: d-Val-Leu-Arg 4NA; VLLNA: d-Val-Leu-Lys 4NA; SPI: Serine proteinase inhibitor; KPI: Kunitz protease inhibitor.