Table 1.

Redox transitions and rate constants of the fast kinetics of reduction by NADH of wild-type Na⁺-NQR, NqrB-D346A and NqrB-D397A mutants

		Rate constants (s-1)
Enzyme	NaCl	K1	K2	K3	K4
WT
	0	249.3	15.4	4.2	0.31
		FAD → FADH2	RibH• → RibH2	2(FMN → FMN•-)
	100	143.2	35.1	0.7
		FAD → FADH2; RibH• → RibH2	2(FMN → FMN•-)
NqrB-D346A
	0	235	20.1	3.6	0.3
		FAD → FADH2		; Rib → RibH•
	50	121.6	16.4	1.5	0.2
		FAD → FADH2;	; Rib → RibH•		RibH• → RibH2
NqrB-D397A
	0	268	4.2	0.3
		FAD → FADH2	RibH• → RibH2; 2(FMN → FMN•-)
	50	270	4.6	0.35
		FAD → FADH2	RibH• → RibH2; 2(FMN → FMN•-)
	200	258	5.1	0.4
		FAD → FADH2	RibH• → RibH2; 2(FMN → FMN•-)

Desalted samples were mixed with 250 μM NADH using different concentrations of sodium.