TABLE 2.
Second-order rate constants for the reaction of MB with biologically relevant reductants under aerobic conditions
| Reductant | k (M−1 s−1) | Buffer system used (pH) |
|---|---|---|
| NADH | 3.8 | LipDH assay buffer (7.4) |
| 2.5 | 0.3 M ethanol and 1 mM LipS2 in LipDH assay buffer | |
| NADPH | 6.6 | GR assay buffer (6.9) |
| 8.0 | GR assay buffer (6.5) | |
| 3.6 | TrxR assay buffer (7.4) | |
| GSH | <0.5a | GR assay buffer (6.9) |
| P. falciparum thioredoxin | 8.5 | TrxR assay buffer (7.4) |
| D. melanogaster thioredoxin | 27.0 | TrxR assay buffer (7.4) |
| d,l-Dihydrolipoamide | 53.1 | LipDH assay buffer (7.4) |
| 1,4-Dithioerythritol | 12.4 | TrxR assay buffer (7.4) |
a
For the slow reaction 2 GSH + MB+→leucoMB + GSSG + H+, no rate constant could be determined. The half-life of GSH was approximately 6 h when 100 μM GSH was incubated with 25 μM MB (31).