Sulfur dioxygenase that plays an essential role in hydrogen sulfide catabolism in the mitochondrial matrix. Hydrogen sulfide (H(2)S) gives rise to cysteine persulfide residues. ETHE1 consumes molecular oxygen to catalyze the oxidation of the persulfide, once it has been transferred to a thiophilic acceptor, such as glutathione (R-SSH). Plays an important role in metabolic homeostasis in mitochondria by metabolizing hydrogen sulfide and preventing the accumulation of supraphysiological H(2)S levels that have toxic effects, due to the inhibition of cytochrome c oxidase. Required for normal endosperm development in seed, and thereby also required for normal embryo development. H2O + O2 + S-sulfanylglutathione = glutathione + 2 H(+) + sulfite Binds 1 Fe(2+) ion per subunit. Homodimer. A number of isoforms are produced. According to EST sequences. Embryonic lethality at the early heart stage, due to defects in endosperm development. Belongs to the metallo-beta-lactamase superfamily. Glyoxalase II family. Was initially thought to be a glyoxalase II isozyme (PubMed:9349270), but has been shown to lack glyoxalase activity (PubMed:22786886). Truncated N-terminus. Truncated N-terminus. Truncated N-terminus. Truncated N-terminus.