Table 1.
Protection factors (krc/kobs) of backbone amides measured for DHFR bound to GroEL and for native DHFR–MTX
| Residue | GroEL bound, krc/kobs | Native state, krc/kobs × 10−3 |
|---|---|---|
| N5 | <5 | 13,000 (12) |
| C6 | <11 | 32,000 (9) |
| I7 | 14 (24) | 39,000 (44) |
| V8 | 12 (12) | 5,300 (42) |
| A9 | 20 (30) | 190 (13) |
| V10 | 10 (15) | 5,700 (26) |
| S11 | <5 | 8,400 (11) |
| M14 | <5 | 260 (12) |
| G15 | <5 | 480 (13) |
| I16 | <5 | 810 (13) |
| G17 | <5 | 88 (14) |
| W24 | 10 (22) | 64 (13) |
| F31 | <5 | 36 (13) |
| R32 | <5 | 1,900 (93) |
| Y33 | <5 | 66 (20) |
| F34 | 16 (20) | 7,000 (15) |
| Q35 | <5 | 4,100 (9) |
| R36 | <5 | 2,000 (19) |
| M37 | <5 | 4,200 (10) |
| T38 | <5 | 6,900 (10) |
| T39 | <5 | 4,300 (7) |
| N48 | <7 | 390 (16) |
| L49 | 6 (32) | 11,000 (22) |
| V50 | 5 (17) | 16,000 (75) |
| I51 | 9 (19) | 15,000 (67) |
| M52 | 9 (40) | 40,000 (47) |
| F58 | 7 (26) | 14,000 (31) |
| S59 | <5 | 9,200 (7) |
| I60 | 6 (37) | 17,000 (31) |
| N64 | <7 | 440 (9) |
| I71 | 4 (20) | 7,500 (22) |
| L73 | 10 (44) | 52,000 (54) |
| V74 | 6 (13) | 21,000 (10) |
| L75 | 2 (23) | 7,700 (36) |
| S76 | <5 | 390 (6) |
| L97 | 13 (16) | 890 (8) |
| M111 | 12 (14) | 290 (26) |
| V112 | 33 (11) | 31 (9) |
| W113 | 40 (9) | 48,000 (10) |
| I114 | 54 (13) | 8,800 (55) |
| V115 | 27 (11) | 2,300 (26) |
| G116 | <5 | 170 (10) |
| A124 | <5 | 77 (8) |
| M125 | <5 | 83 (9) |
| K132 | 5 (22) | 2,500 (11) |
| L133 | 9 (20) | 11,000 (34) |
| F134 | 12 (12) | 41,000 (65) |
| V135 | 11 (11) | 35,000 (65) |
| T136 | 14 (14) | 110,000 (10) |
| R137 | 34 (19) | 330,000 (10) |
| I138 | 17 (10) | 53,000 (10) |
| M139 | 14 (25) | 62 (12) |
| Q140 | 8 (33) | 260 (7) |
| F148 | 26 (28) | 2,300 (8) |
| Y156 | 19 (11) | 320 (18) |
| K157 | 22 (20) | 2,600 (5) |
| L159 | 24 (9) | 1,100 (8) |
| E172 | <5 | 810 (42) |
| I175 | 2 (29) | 16 (10) |
| Y177 | 9 (29) | 10,000 (11) |
| K178 | 5 (22) | 16,000 (15) |
| F179 | 4 (25) | 7,600 (10) |
| E180 | 4 (24) | 15,000 (34) |
| V181 | 5 (13) | 150 (10) |
| Y182 | 12 (13) | 1,200 (11) |
| W24-Hɛ | <5 | 180 (10) |
| W57-Hɛ | <5 | 89 (7) |
| W113-Hɛ | 48 (20) | 170,000 (19) |
The last three lines show protection factors for the indole side chain NH protons of the three tryptophans in DHFR. For each protection factor, the error (parentheses) represents 1 SD, as a percentage of the listed value, estimated by Monte Carlo simulation (24). For the probes washed out during refolding, only upper bounds are listed. A protection factor of 5 implies that the amide is hydrogen bonded or otherwise protected from exchange 80% of the time; a protection factor of 10 implies 90% of the time.