TABLE 3.
Substrate specificity of LmNTR
The apparent Vmax and Km values of His-tagged LmNTR toward various nitroaromatic and quinone-based substrates were determined in the presence of NADH (“Experimental Procedures”). The kcat/Km value (the “specificity constant”) was then determined providing a useful ratio for comparing the relative rates of LmNTR activity on various substrates.
| Compound | Apparent Km | Apparent Vmax | kcat/Km |
|---|---|---|---|
| μm | nmol min−1 mg−1 | m−1 s−1 | |
| Nitroimidazole | |||
| Benznidazole | 22.0 ± 0.4 | 78.7 ± 1.0 | 2.5 × 103 |
| Metronidazole | 2.4 ± 0.0 | 17.9 ± 0.0 | 5.2 × 103 |
| Nitrofuran | |||
| Nifurtimox | 9.7 ± 1.1 | 50.9 ± 7.0 | 3.7 × 103 |
| Nitrofurazone | 4.7 ± 0.6 | 68.3 ± 10.0 | 1.0 × 104 |
| Nitrofurantoin | 3.9 ± 0.5 | 56.7 ± 8.0 | 1.0 × 104 |
| Nitrobenzyl | |||
| CB1954 | 13.1 ± 0.1 | 85.9 ± 1.0 | 4.6 × 103 |
| LH32 | 28.8 ± 2.7 | 100.7 ± 10.0 | 2.5 × 103 |
| LH33 | 8.2 ± 1.0 | 114.2 ± 15.0 | 9.8 × 103 |
| LH37 | 7.1 ± 0.4 | 71.7 ± 5.0 | 7.1 × 103 |
| Quinone | |||
| Duroquinone | 9.8 ± 0.3 | 140.6 ± 5.0 | 1.0 × 104 |
| Coenzyme Q1 | 5.1 ± 0.4 | 145.2 ± 11.0 | 2.0 × 104 |