Table 7.
Equilibrium isotope effects on nucleophile (2′-OH) deprotonation of the (A) native, (B) S3′, and (C) S5′ simplest models of RNA transphosphorylation in solution. All values are computed from the Bigeleisen equation.
| Native (37°C) | Equilibrium Isotope Effects in Solution (ratio of isotopic equilibrium constants) Nucleophile (2′-OH) deprotonation |
||||
|---|---|---|---|---|---|
| Electronic Struct. Theory | 18ENuc | 18ELea | 18EO3′ | 18EO1P | 18EO2P |
|
|
|
||||
| HF/3-21+G* | 1.0245 | 1.0020 | 0.9985 | 0.9991 | 0.9999 |
| B3LYP/6-31+G(d) | 1.0210 | 1.0007 | 1.0012 | 0.9999 | 1.0008 |
| M06-2X/6-31+G(d) | 1.0214 | 1.0015 | 0.9975 | 1.0000 | 0.9998 |
| B3LYP/6-311+G(d,p) | 1.0220 | 1.0007 | 1.0013 | 0.9997 | 1.0011 |
| M06-2X/6-311+G(d,p) | 1.0222 | 1.0016 | 0.9977 | 0.9999 | 1.0001 |
| MP2/6-311+G(d,p) | 1.0218 | 1.0020 | 0.9984 | 1.0004 | 1.0003 |
|
| |||||
| (A) | |||||
| S3′ (37°C) | Equilibrium Isotope Effects in Solution (ratio of isotopic equilibrium constants) Nucleophile (2′-OH) deprotonation |
||||
|---|---|---|---|---|---|
| Electronic Struct. Theory | 18ENuc | 18ELea | 34ES3′ | 18EO1P | 18EO2P |
|
|
|
||||
| HF/3-21+G* | 1.0266 | 1.0002 | 1.0000 | 1.0003 | 0.9995 |
| B3LYP/6-31+G(d) | 1.0196 | 1.0005 | 1.0003 | 1.0007 | 1.0006 |
| M06-2X/6-31+G(d) | 1.0244 | 1.0002 | 1.0009 | 1.0005 | 0.9998 |
| B3LYP/6-311+G(d,p) | 1.0208 | 1.0005 | 1.0003 | 1.0008 | 1.0006 |
| M06-2X/6-311+G(d,p) | 1.0255[a] | 1.0003[a] | 1.0009[a] | 1.0005[a] | 1.0000[a] |
| MP2/6-311+G(d,p) | 1.0271 | 1.0001 | 1.0007 | 1.0004 | 1.0004 |
|
| |||||
| (B) | |||||
| S5′ (37°C) | Equilibrium Isotope Effects in Solution (ratio of isotopic equilibrium constants) Nucleophile (2′-OH) deprotonation |
||||
|---|---|---|---|---|---|
| Electronic Struct. Theory | 18ENuc | 34ELea | 18EO3′ | 18EO1P | 18EO2P |
|
|
|
||||
| HF/3-21+G* | 1.0259 | 0.9997 | 1.0001 | 1.0002 | 1.0014 |
| B3LYP/6-31+G(d) | 1.0204 | 1.0002 | 1.0026 | 1.0011 | 1.0004 |
| M06-2X/6-31+G(d) | 1.0215 | 0.9994 | 1.0024 | 1.0005 | 1.0011 |
| B3LYP/6-311+G(d,p) | 1.0215 | 1.0002 | 1.0027 | 1.0012 | 1.0004 |
| M06-2X/6-311+G(d,p) | 1.0222 | 0.9993 | 1.0022 | 1.0004 | 1.0012 |
| MP2/6-311+G(d,p) | 1.0225 | 0.9999 | 1.0002 | 1.0004 | 1.0001 |
|
| |||||
| (C) | |||||
[a]
As in Table 2, the ground state after deprotonation is determined but along with very small value of non-reactive imaginary frequency.