Table 1.
Unique preferred substrates with natural amino acids
Based on screening of a natural amino acid HyCoSuL library, single substrates were synthesized for caspase-1 and caspase-11. Each substrate was assayed with either caspase-1 or caspase-11. All synthesized natural amino acid substrates were preferred by caspase-1, even those that had the highest catalytic numbers for caspase-11. The selectivity factor represents the catalytic parameter kcat/Km for caspase-1 divided by that for caspase-11. Each experiment was repeated at least three times, and the kcat/Km values are presented as an average. Standard deviations were below 15%.
| Substrate sequence: Ac-P4-P3-P2-P1-ACC |
kcat/Km |
Selectivity factor | |
|---|---|---|---|
| Caspase-1 | Caspase-11 | ||
| m−1s−1 | |||
| Reference substrates | |||
| WEHD | 522,000 | 4,100 | 127 |
| LEHD | 179,000 | 3,850 | 47 |
| Caspase-1 preferred | |||
| WQPD | 257,000 | <50 | >5,140 |
| FEAD | 171,000 | <50 | >3,420 |
| WQVD | 328,000 | 244 | 1,340 |
| Caspase-11 preferred | |||
| PYHD | 22,400 | 7,070 | 3.2 |
| PMHD | 16,100 | 7,200 | 2.2 |