Table 1.

Effects of subunit V isozymes and YHb on NO₂⁻-dependent NO production in yeast cells

Strain	Subunit V isozyme	YHb	NO production, pmol NO/g wet weight per min*	In vivo turnover rate, pmol NO × 10−1/min per pmol aa3†
JM43	Va	+	78 ± 32	0.07 ± 0.03
JM43ρ0	Va	+	00 ± 20	-
DR11	Va	−	240 ± 60	0.21 ± 0.05
DR10	Va	−	20 ± 10	-
GD5b	Va	+	36 ± 32	0.04 ± 0.03
CT4F	Vb	+	114 ± 32	0.30 ± 0.08
DW29	Va	−	168 ± 40	0.18 ± 0.04
DW27	Vb	−	336 ± 32	0.89 ± 0.08

*Cells (160 mg) were suspended in 2 ml of NO assay buffer and prebubbled for 5 min with N₂ to create anoxic conditions. After 5 min of prebubbling NaNO₂ was added to 1 mM, and NO production was measured with an NO polarographic electrode.

^†Turnover rate was calculated by normalizing the rate of NO production to the cytochrome aa₃ content of each strain, determined as described (31). Intracellular aa₃ contents were 5.6 μM aa₃/g wet weight for strains JM43 and DR11; 4.6 μM aa₃/g wet weight for strains GD5b and DW29, and 1.9 μM aa₃/g wet weight for strains CT4F and DW27. Strains JM43 ρ⁰ and DR10 lack detectable cytochromes aa₃.