. Author manuscript; available in PMC: 2010 Oct 13.

Published in final edited form as: Biochemistry. 2009 Oct 13;48(40):9516–9524. doi: 10.1021/bi900845y

Table 6.

Apparent kinetic parameters of the wild-type Na⁺-NQR and acid mutants.

Subunit	Mutant	Orientation	Km_app_Na⁺ (mM)	Vmax_Na+/ Vmax_noNa⁺
	WT		1.1	6.2
B	E28A	P	2.1	3.5
	E144L	N	4.2	4.8
	D346A	P	0.9	1.4
	D397A	N	>100	-
D	D88L	P	1.4	3.1
	D133A	N	9.3	2.8
E	E95A	N	13.1	1.3

The Qred activity of the mutants was measured with different concentrations of NaCl using near saturating amounts of NADH (150 µM) and Q-1(50 µM). The kinetic parameters were calculated from the saturation curve using the Michaelis-Menten equation. The orientation was obtained from the topology studies published previously (15). N; negative side of the membrane (facing the cytosol), P; positive side of the membrane (facing the periplasmic space).