Table 1.

Affinity of the cbb₃ isoforms for oxygen

Isoforms	Km (μM)	Vmax (nmol O2/min/mg-protein)
CcoN1O1P1	0.012 ± 0.003	11 ± 3
CcoN1O2P2	0.027 ± 0.003	24 ± 5
CcoN2O1P1	0.016 ± 0.006	16 ± 3
CcoN2O2P2	0.022 ± 0.005	34 ± 3
CcoN3O1P1	0.121 ± 0.024	25 ± 7
CcoN3O2P2	0.151 ± 0.039	21 ± 5
CcoN4O1P1	0.046 ± 0.015	15 ± 2
CcoN4O2P2	0.035 ± 0.015	52 ± 13

K_m values for oxygen were determined using the deoxygenation kinetics of oxymyoglobin. Values are presented as means ± SDs from three independent experiments. Membrane fractions of the cells of strain STO7 transformed with the plasmids expressing only one of the cbb₃ isoforms were used for determination of the oxygen affinity (Fig. S1).