TABLE 3.
Percentages of amino acids in substrate‐binding sites P4‐P4'
| Amino acid | P4 | P3 | P2 | P1 | P1' | P2' | P3' | P4' |
|---|---|---|---|---|---|---|---|---|
| ‐ | 10.5 | 8.2 | 6.5 | 0 | 0 | 4.3 | 5.3 | 6.2 |
| Ala | 7.6 | 9 | 8.5 | 7 | 11.1 | 8.9 | 7.9 | 7.3 |
| Arg | 4.6 | 4 | 3.7 | 17 | 3.1 | 4.1 | 3.3 | 3 |
| Asn | 2.9 | 2.8 | 2.8 | 4 | 2.9 | 3 | 3.5 | 3.5 |
| Asp | 4.9 | 3.8 | 2.7 | 8.5 | 4.4 | 4.6 | 5.6 | 7.1 |
| Cys | 1.2 | 1.3 | 1.2 | 0.9 | 1.1 | 1 | 1.3 | 1.1 |
| Glu | 6.5 | 6.9 | 6 | 8.2 | 4.9 | 6.7 | 7.6 | 8.7 |
| Gln | 3.9 | 4.1 | 4.1 | 2.8 | 3.1 | 4.4 | 4.5 | 4.5 |
| Gly | 6.7 | 6.5 | 6.3 | 5.8 | 7.8 | 6.9 | 8.3 | 7.6 |
| His | 1.9 | 1.8 | 1.6 | 1.2 | 1.8 | 2 | 2 | 1.9 |
| Ile | 4.4 | 4.7 | 4.6 | 0.7 | 5.7 | 5.2 | 4.4 | 4.2 |
| Leu | 7.8 | 8.4 | 11.7 | 5.6 | 11 | 8.9 | 7.9 | 6.9 |
| Lys | 5.2 | 5.1 | 5 | 15.7 | 6.8 | 5.2 | 5.1 | 5 |
| Met | 1.9 | 2 | 2 | 6 | 2.4 | 1.8 | 1.7 | 1.5 |
| Phe | 3.1 | 3.5 | 4.3 | 3.8 | 4.5 | 3.4 | 3.2 | 2.9 |
| Pro | 5.8 | 5.6 | 5.6 | 2 | 1.5 | 5.2 | 6.2 | 7.3 |
| Ser | 6 | 6 | 5.9 | 3.6 | 9.3 | 6.8 | 6.8 | 6.5 |
| Thr | 4.4 | 4.7 | 4.4 | 2.6 | 4.7 | 5.6 | 5.2 | 5.3 |
| Trp | 0.8 | 0.7 | 0.9 | 0.7 | 0.7 | 0.8 | 0.8 | 0.8 |
| Tyr | 2.3 | 2.2 | 2.7 | 2.5 | 2.8 | 2.7 | 2.4 | 2.1 |
| Val | 6.5 | 7.6 | 8.6 | 1.4 | 7.2 | 8 | 6.6 | 6.1 |
| X | 1 | 0.9 | 0.9 | 0.2 | 3 | 0.3 | 0.3 | 0.4 |
Note: Standard amino acids are included, plus “‐” to indicate an unoccupied site and “X” to indicate a nonstandard amino acid or other moiety. An amino acid that occupies a substrate‐binding site in 10% or more cleavages is highlighted in yellow. An amino acid that occupies a substrate‐binding site in less than 1% of cleavages is highlighted in orange.