Table 2.
Steady-state kinetics of AfNpsr under aerobic conditions at 70°C.
| Substratea | k cat (s−1) | K m (mM) | k cat/Km (M−1 s−1) |
|---|---|---|---|
| NADHb | 7.15 ± 0.51 | 0.0206 ± 0.0051 | 3.47 ± 0.75 × 105 |
| NADPHb | NRc | — | — |
| DTNB | 2.44 ± 0.14 | 0.743 ± 0.196 | 3.28 ± 0.48 × 103 |
| Coenzyme A disulfide | NR | — | — |
| Glutathione disulfide | NR | — | — |
| Cystine | NR | — | — |
| Coenzyme A persulfide | 13.2 ± 0.3 | 0.547 ± 0.041 | 2.41 ± 0.14 × 104 |
| Glutathione persulfide | 29.8 ± 1.2 | 1.25 ± 0.23 | 2.44 ± 0.49 × 104 |
| Cysteine persulfide | 230 ± 23 | 3.41 ± 0.63 | 6.76 ± 1.1 × 104 |
| Polysulfided | 42.0 ± 2.2 | 0.616 ± 0.058 | 6.82 ± 0.29 × 104 |
aAll reactions performed with di-, per-, and polysulfide substrates contained 100 μM NADH. bNAD(P)H oxidase activity. No di-, per-, or polysulfides were present. cNR: no reaction. dThe reaction was performed in 1 M Tris, pH 8.7, as in (8).