Table 1.

Sulfide:quinone reductase activity of SQR with sulfide as the substrate in the presence of different quinones as the electron acceptor. 100 nM SQR was reacted with 100 μM ubiquinone-1 or menadione, 4 mM KCN and Na₂S ranging from 0 to 640 μM.

Electron acceptor	K m for sulfide (μM)	V max (μmol min −1 μmol −1)	k cat /K m (M−1 s−1)
Ubiquinone-1	186 ± 43	234 ± 22	(2.1 ± 0.5) × 104
Menadione	45 ± 11	95 ± 6	(3.5 ± 0.9) × 104