Skip to main content
. Author manuscript; available in PMC: 2022 Jun 1.
Published in final edited form as: Crit Rev Biochem Mol Biol. 2021 Mar 15;56(3):221–235. doi: 10.1080/10409238.2021.1893641

Figure 2. H2S interactions with the ETC.

Figure 2.

Oxidation of H2S by SQOR requires CoQ (Q), which is also used as an electron acceptor by other enzymes and by complexes I and II. At higher concentrations, H2S inhibits the ETC by targeting complex IV. H2S oxidation limits the oxidized CoQ pool which together with complex IV inhibition is predicted to lead to a reductive shift in the NAD+/NADH, FAD/FADH2 and CoQ/CoQH2 redox couples, affect the proton motive force and decrease ATP. Under these conditions, the NADPH concentration could also increase via the activity of the nucleotide transhydrogenase (NNT). DHOD, G3PDH, ETF and PDH denote dihydroorotate dehydrogenase, glycerol 3-phosphate dehydrogenase, electron transfer flavoprotein and proline dehydrogenase, respectively.