Table 2.
Trp/Trp mutants of the Schenk-Gellman double hairpin: ring current shifts, CD exciton couplet amplitudes, and fold populations (including those for unmodified reference compounds).
| Turn1/2 | HP1 | HP2 | S±4 W’s | S±2 W’s | ||||
|---|---|---|---|---|---|---|---|---|
| χF(1) | χF(2) | χF (1) | W11Hε3b | [θ]228 c | χF (1) | W4Hε3b | [θ]228 c | |
| pG/pG | 0.718 | 0.811 | 0.92 | −2.03 | +360 | ≥0.96 | −1.55 | +309 |
| pG/NG | 0.668 | 0.563 | ||||||
| pG/PG | 0.557 | -- | ||||||
| NG/pG | 0.365 | 0.682 | 0.84 | −1.94 | +330 | 0.90 | −1.70 | +285 |
| NG/NG | 0.247 | 0.461 | 0.85 | −1.68 | n. d. | |||
| NG/PG | 0.104 | -- | 0.80 | −2.05 | +370 | 0.73 | −1.73 | +120 |
| T4A | ||||||||
| pG/pG | n.d. | 0.82 | −1.83 | +440 | ||||
| pG/PG | n.d. | 0.65 | −1.91 | +470 | ||||
a
Fold population are given for each hairpin that can form, χF(1) and χF(2). The data for the species lacking Trp substitution are taken from Hudson46.
b
The CSD of Hε3 of the edge indole at 280K is given in ppm. These were not corrected so as to represent the values at 100% folded. The largest upfield shift observed for any proton sites on the other indole ring was 0.27 ppm.
c
Ellipticity values are reported in 10−3 molar ellipticity units.