Table 1. Summary of ThdG Impact on GQ Folding, OTA Binding, and Predicted Location of the ThdG Probe within the Antiparallel GQ.
| ID | Tm (ΔTm)a | λex (290)b | GQc | location | Kdd |
|---|---|---|---|---|---|
| OTAA | 46.6 | yes | 1.1 ± 0.2 | ||
| ThdG-5 | (−0.5) | yes | no | 5′-tail | 19.9 ± 2.7 |
| ThdG-6 | (+6.4) | yes | yes | syn-tetrad | 10.5 ± 2.2 |
| ThdG-7 | (−8.4) | yes | no | anti-tetrad | NBe |
| ThdG-11 | (+3.4) | yes | yes | syn-tetrad | 2.1 ± 0.3 |
| ThdG-12 | (−7.5) | yes | no | anti-tetrad | NB |
| ThdG-13 | (−2.3) | no | yes | loop | 3.3 ± 0.4 |
| ThdG-23 | (+3.0) | yes | no | loop | NB |
| ThdG-24 | (+9.2) | yes | yes | syn-tetrad | NB |
| ThdG-25 | no Tm | yes | no | anti-tetrad | NB |
a
Tm of GQ in degree Celsius, ΔTm = Tm (mOTAA GQ) – Tm (native OTAA).
b
Presence of the excitation peak at 290 nm for probe-G-tetrad stacking interactions.
c
Formation of antiparallel GQ, as evidenced by CD.
d
Dissociation constant (μM) for OTA binding measured by changes in the intrinsic fluorescence of OTA upon aptamer additions.
e
No binding (NB) observed from fluorescence titration.