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. 2021 Feb 9;143(7):2694–2698. doi: 10.1021/jacs.0c13423

Table 1. Kinetic Parameters at pH 7.5 and 25 °C for Enzyme-Catalyzed Reactions of Whole and Phosphodianion Truncated Substrates (Scheme 2), the Total Phosphodianion Binding Energies, and the Dianion Binding Energy Utilized for Enzyme Activation.

  (kcat/Km)SPi (kcat/Km)S Inline graphic G)Pi (kcal/mol),h,j ΔGHPi  (kcal/mol),i,j  
enzyme (M–1 s–1)e,f (M–1 s–1)e,f (M–2 s–1)f,g [IBE]T [IBE]HPi [IBE]HPi/[IBE]T
ScPGIa (6.9 ± 0.2) × 105 (3.6 ± 0.2) × 10–4 0.52 ± 0.10 12.6 ± 0.1 4.3 ± 0.1 0.34
kcat = 400 s–1
LmG6PDHa (2.0 ± 0.2) × 106 (8.3 ± 0.1) × 10–3 53.0 ± 0.3 11.4 ± 0.1 5.2 ± 0.1 0.46
kcat = 320 s–1
Ec6PGDHb (8.4 ± 0.4) × 105 (9.9 ± 0.2) × 10–3 140 ± 1 10.8 ± 0.1 5.7 ± 0.1 0.53
kcat = 12 s–1
OMPDCc 1.1 × 107 0.026 12000 11.7 ± 0.1 7.7 ± 0.1 0.66
TIMd 2.2 × 108 0.062 2700 13.0 ± 0.1 6.3 ± 0.1 0.48
GPDHd 4.6 × 106 0.050 16000 10.8 ± 0.1 7.5 ± 0.1 0.69
a

SPi = G6P; S = d-xylose.

b

SPi = 6-PG; S = d-xylonate.

c

SPi = orotidine 5′-monophosphate (OMP); S = 1-(β-d-erythrofuranosyl)orotic acid.6,18

d

SPi = dihydroxyacetone phosphate; S = glycolaldehyde.2,6

e

Kinetic data for the catalyzed reactions of whole or truncated substrate (see SI).

f

The quoted uncertainty is the standard error obtained from the least-squares fit of experimental data to the appropriate kinetic equation.

g

Third-order rate constant for the phosphite dianion-activated reaction of truncated substrate (Scheme 3).

h

G)Pi = RT ln[(kcat/Km)SPi/(kcat/Km)S].

i

See eq 3.

j

The approximate uncertainties are calculated from the standard errors in the kinetic parameters.