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. 2014 Jun 5;53(27):4476–4487. doi: 10.1021/bi500491w

Table 2. Kinetic Parameters for Inhibition of hBChE Variants by Nerve Agent Model Compoundsa.

  kib (μM–1 min–1) k2c (min–1) KDd (μM) t1/2 (min)e R2f
SPGB3N
wild type 0.14 ± 0.08 1.17 ± 0.31 8.4 ± 3.9 3.8 ± 2.5g 0.97
Y332S 0.01 ± 0.01 0.52 ± 0.09 50.9 ± 11 9.5 ± 3.0g 0.99
D340H 0.03 ± 0.02 0.48 ± 0.04 19.0 ± 2.6 4.9 ± 1.3g 0.99
Y332S/D340H 0.002 ± 0.001 0.22 ± 0.35 132.0 ± 23.3 58 ± 2.16g 0.94
G117H 3.62 ± 3.03 0.02 ± 0.003 6202 ± 833 NAh 0.99
SPGD3N
wild type 0.11 ± 0.05 0.58 ± 0.11 5.2 ± 2.2 4.0 ± 2.4g 0.96
Y332S 0.02 ± 0.01 0.24 ± 0.16 10.9 ± 1.18 22.6 ± 1.57g 0.85
D340H 0.04 ± 0.02 0.20 ± 0.08 5.4 ± 0.42 16.2 ± 1.07g 0.84
Y332S/D340H 0.03 ± 0.01 0.03 ± 0.004 1.1 ± 0.5 38.9 ± 7.5g 0.76
G117H 71.4 ± 5.59 0.19 ± 0.09 2613 ± 1500 NAh 0.97
SPGF3N
wild type 2.03 ± 1.21 0.23 ± 0.01 0.11 ± 0.014 21.1 ± 8.97g 0.99
Y332S 0.71 ± 0.35 0.04 ± 0.01 0.06 ± 0.015 43.0 ± 16.2g 0.99
D340H 0.91 ± 0.45 0.05 ± 0.002 0.06 ± 0.005 48.6 ± 2.82g 0.99
Y332S/D340H 0.31 ± 0.04 0.27 ± 0.05 0.88 ± 0.124 42.4 ± 9.85g 0.92
G117H 4.3 ± 3.49 0.02 ± 0.02 3460 ± 7385 NAh 0.87
a

Values for k2 and KD were derived from the nonlinear curve fit of kapp over nerve agent model compound concentrations. Values reported represent best fit values ± the standard deviation derived from fitting 30–40 data points from a single experiment. Values for ki were calculated from k2/KD ratios. Statistical significance was evaluated by ANOVA followed by a Dunnett’s multiple-comparison test.

b

Bimolecular inhibition constant (ki).

c

Phosphonylation constant (k2).

d

Equilibrium dissociation constant (KD).

e

Half-life value for 50% inhibition of BTC hydrolysis.

f

Correlation constant for a nonlinear curve fit (R2).

g

Half-life values calculated for five concentrations of nerve agent model compounds.

h

Half-life value could not be calculated.