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. 2024 Mar 13;121(12):e2319473121. doi: 10.1073/pnas.2319473121

Fig. 2.

Fig. 2.

H2S increases P50(O2) for complex IV. (A) Postulated mechanism for sulfide binding to the metal sites in the MT-CO1 subunit of complex IV. (B) Inhibition of OCR as a function of sulfide concentration in HT29Scr (purple) and HT29SQOR KD (blue) cells yielded IC50 estimates of 30 ± 1 and 6.0 ± 0.3 µM, respectively. Data represent the mean ± SD of three to five independent experiments. (C) Dependence of P50(O2) (blue) and Jmax(O2) (purple) values on sulfide concentration in HT29 cells. Data represent the mean ± SD of at least three independent experiments. (D and E) Na2S increases the P50(O2) and decreases the Jmax(O2) value in HT29SQOR KD (at 10 µM) but not in HT29Scr cells (n = 4). (F) The P50(O2) and Jmax(O2) of HEK293 and 143B cells are significantly altered by 20 µM Na2S as in HT29 cells, while Ea.hy926 cells need 40 µM Na2S for similar modulation (n = 3). The two-sample unpaired t test was performed for statistical analysis.