Table 1.
H-bonds involving the observed hydrogens in x-ray and NMR structures
| Donor | Acceptor |
Donor | Acceptor |
Donor | Acceptor |
|||
|---|---|---|---|---|---|---|---|---|
| X-ray | NMR | X-ray | NMR | X-ray | NMR | |||
| 6 | 28 | 28 (20) | 38 | 81 | 38sc (2) | 70 | 21 | 68 (10) |
| 8 | 26 | 26 (20) | 39 | water | — | 79 | 40 | 40 (18) |
| 10 | 24 | 24 (20) | 40 | 79 | 79 (20) | 80 | 93 | 93 (19) |
| 22 | 12 | 21sc (12) | 41 | 44 | 44 (20) 41sc (1) | 81 | 38 | 38 (20) |
| 23 | 68 | 68 (20) | 42 | 77 | 42sc (9) | 82 | 91 | 91 (16) 80 (1) |
| 24 | 10 | 10 (20) | 44 | 41 | — | 83 | 36 | 36 (20) |
| 25 | 66 | 66 (18) | 46 | 39 | 39 (19) | 84 | water | — |
| 26 | 8 | 8 (7) 24 (10) | 63 | 55 | 55 (1) | 86 | 84Nsc | 84Nsc (19) 84 (1) |
| 27 | 64 | 64 (3) | 64 | 27 | 27 (8) | 87 | 84 | 84 (20) |
| 28 | 6 | 6 (20) | 65 | 53 | 52 (8) | 91 | 82 | 82 (20) |
| 30 | 62 | 28 (9) 62 (1) | 66 | 25 | 25 (11) | 93 | 80 | 80 (12) 91 (8) |
| 35 | — | 33 (10) | 67 | 51 | 50 (14) | 95 | 78 | 78 (16) |
| 36 | 83 | 83 (20) | 68 | 23 | 23 (20) | |||
The x-ray structure is from PDB file 1LDS (43), and the NMR structure is from PDB file 1JNJ (42). A hydrogen bond is considered to be formed when the distance between the proton on the donor atom and the heavy atom acceptor is <2.5 Å; in addition, the angle formed by the proton-donor atom vector with the proton-acceptor atom vector must be >120°. Where not specified, the acceptor atom is the backbone carboxylic oxygen of the residue indicated by the number; the superscript “sc” indicates that the acceptor atom belongs to the side chain of the residue. For NMR structures, the number shown in parentheses indicates the occurrences of hydrogen bonds over the 20 structures.