Table 4.
Values of kcat/Km (M−1 s−1) for wild-type and mutant forms of PTE against the nerve agents GB and GD.
| compound | GB | GD | |||
|---|---|---|---|---|---|
| kcat/Km1a | kcat/Km2 | kcat/Km1 | kcat/Km2 | Enantiomeric Preferenceb |
|
| Wild-type | (9±3) × 104 | (2.6±0.2) × 103 | RpSc,RpRc,SpRc>>SpSc | ||
| G60A | (1.2±0.1) × 105 | (2.66±0.01) × 104 | (2.5±0.3) ×104 | (2.2±0.3) × 103 | RpSc,RpRc>SpSc,SpRc |
| S308G | (3.9±0.9) × 104 | (9.1±0.5) × 103 | (8±2) × 102 | RpRc,RpSc>SpRc>>SpSc | |
| H254G/ H257W/ L303T |
(1.5±0.1) × 104 | (9.7±0.1) ×102 | (2.2±0.2) × 103 | SpSc,SpRc>>RpSc,RpRc | |
| H275Y/ L303T |
(3±1) × 105 | (3.65±0.01) × 104 | (8.9±0.9) × 104 | (6.8±0.2) × 103 | SpSc,SpRc>RpSc,RpRc |
a
kcat/Km1 and kcat/Km2 were determined from the first and second exponential phases, respectively, during the reaction of GB or GD as followed by ITC.
b
first phase > second phase >> not observed.