TABLE 1.
Activation barriers and selected geometric parameters for PP2A(PPP2R5D)/pSer hydrolysis a .
| Reactant state | Transition state | ΔH‡ (kcal/mol) b | |||||
|---|---|---|---|---|---|---|---|
| Inversion dihedral c | r(P-Oγ) (Å) | Inversion dihedral c | r(P-Oγ) (Å) | r(P-OW1) (Å) | Gas phase | Solvent corrected | |
| Pathway I: Model A | −23.7° | 1.711 | +10.6° | 2.492 | 1.889 | +24.3 | +15.5 |
| Pathway I-alt: Model A d | −24.7° | 1.713 | +8.9° | 2.427 | 1.928 | +24.5 | +16.4 |
| Pathway II-alt: Model B d | −25.3° | 1.700 | 0.0° | 2.191 | 2.141 | +24.8 | +18.8 |
| Pathway II-alt: Model A d | −25.8° | 1.702 | +5.0° | 2.074 | 2.014 | +26.1 | +22.3 |
| PPP5/pMeOH d | −21.1° | 1.759 | +4.1° | 2.223 | 1.950 | +8.6 | +10.0 |
a
ONIOM(UB3LYP/6-31G(d):UPM7) model systems and atom labeling are shown in Figure 2.
b
ΔH‡ ≈ ΔE‡.
c
Inversion dihedral given by d(O2,O1,O3, P). More positive (or less negative) values favor the product side of the inversion process; the dihedral for bound HPO4 2−is ∼ +21°.
d
The “alt” designation refers to the alternative position taken by W2 indicated in Figure 2.
e
pMeOH, methyl phosphate dianion. Data from Salter et al. (2020).