TABLE 3.
Enzyme-inhibitor interactions in the PPE complex of rShPI-1/K13L
PPE residues are numbered according to their similar topology with chymotrypsinogen. The total number of contacts between a pair of residues (≤4.0 Å) is shown in parentheses, then the closest atoms are listed, and distances (Å) are given in square brackets. Hydrogen bonds, displayed in a bold underlined font, were scored using the PDBe PISA server (57), applying the following parameters: maximal donor-acceptor distance, 3.50 Å; maximal hydrogen-acceptor distance, 2.50 Å; maximal angular errors, 90.00. Enzyme residues Arg217A and Ala99A represent native insertions in the sequence of PPE as compared with chymotrypsin.
| rShPI-1/K13L residue | PPE residue | (Total contacts) Closest atoms [distance] |
|---|---|---|
| [Å] | ||
| P6 Lys8 | Arg217A | (6) CE--NH2 [3.59] |
| P5 Val9 | Gln192 | (1) CG1--NE2 [3.83] |
| P4 Gly10 | Arg217A | (2) C--CG [3.82] |
| P3 Arg11 | Ala99A | (1) NH1--CB [3.87] |
| Thr175 | (1) NH2--OG1 [3.90] | |
| Phe215 | (5) O--CB [3.10] | |
| Val216 | (10) O--N [2.82] | |
| Arg217A | (3) CG--CG [3.47] | |
| P2 Cys12 | His57 | (8) CB--NE2 [3.52] |
| Val99 | (2) SG--CG2 [3.76] | |
| Gln192 | (4) O--OE1 [2.97] | |
| Ser214 | (3) CA--O [3.51] | |
| P1 Leu13 | His57 | (1) N--NE2 [3.86] |
| Gly190 | (3) CD1--C [3.47] | |
| Cys191 | (6) CD2--C [3.56] | |
| Gln192 | (9) CA--OE1 [3.37] | |
| Gly193 | (4) O--N [2.73] | |
| Asp194 | (1) O--N [3.26] | |
| Ser195 | (11) C-OG [2.76]; O--N [3.04] | |
| Thr213 | (1) CD1--CG2 [3.78] | |
| Ser214 | (1) N--O [3.33] | |
| Val216 | (4) CD2--CG2 [3.52] | |
| P1′ Gly14 | Thr41 | (2) C--O [3.86] |
| His57 | (1) N--NE2 [3.75] | |
| Gln192 | (5) O--OE1 [3.02] | |
| Gly193 | (2) C--N [3.58] | |
| Ser195 | (4) N--OG [3.02] | |
| P2′ Tyr15 | His40 | (1) CD2--O [3.87] |
| Thr41 | (8) N--O [3.00] | |
| N--OG1 [3.80] | ||
| Leu143 | (2) CE1--CD1 [3.71] | |
| Leu151 | (11) CD1--CD2 [3.47] | |
| Gly193 | (3) CB--CA [3.69] | |
| P3′ Phe16 | Thr41 | (5) CZ--OG1 [3.62] |
| Cys58 | (1) CZ--O [3.63] | |
| Arg61 | (4) CZ--NE [3.54] | |
| P4′ Pro17 | Tyr35 | (2) CE1--OE1 [3.26] |
| P5′ Arg18 | Arg61 | (1) NH2--NH1 [3.22] |
| 32 Ile32 | Gln192 | (1) CG2--CB [4.00] |
| 34 Gly34 | His57 | (2) O--CD2 [3.64] |
| Gln192 | (1) CA--OE1 [3.70] | |
| 35 Gly35 | His57 | (2) O--O [3.56] |
| Arg61 | (3) O--NH2 [2.77] | |
| 36 Cys36 | Thr96 | (4) CB--O [3.58] |
| Val99 | (2) SG--CB [3.84] | |
| 37 Gly37 | Thr96 | (2) N--O [2.91] |