. Author manuscript; available in PMC: 2017 Nov 29.

Published in final edited form as: Biochemistry. 2016 Nov 16;55(47):6524–6534. doi: 10.1021/acs.biochem.6b00714

Table 2.

Sulfide:Quinone Oxidoreductase Activity of S. aureus SQR with Sulfide as the Substrate in the Presence of Different S⁰ Acceptors^a

S⁰ acceptor	K_m (μM)	V_max (μmol min⁻¹ mg⁻¹)	k_cat (s⁻¹)	k_cat/K_m (M⁻¹ s⁻¹)
KCN	22 ± 7	0.41 ± 0.03	0.31 ± 0.02	(1.41 ± 0.46) × 10⁴
sulfite	249 ± 86	4.51 ± 0.70	3.42 ± 0.53	(1.37 ± 0.52) × 10⁴
CoA^b	32 ± 6	0.25 ± 0.01	0.19 ± 0.01	(0.60 ± 0.12) × 10⁴

Conditions: 40 nM SQR, 60 μM DQ, 4 mM S⁰ acceptor, 25 mM Tris-HCl, 0.2 M NaCl, pH 8.0, 25 °C.

The CoA concentration was 100 μM.