ID   1.8.1.22
DE   dissimilatory sulfite reductase.
AN   siroheme sulfite reductase.
CA   [DsrC protein]-trisulfide + NAD(+) + 3 H2O = [DsrC protein]-dithiol +
CA   sulfite + NADH + 3 H(+).
CC   -!- Contains siroheme.
CC   -!- The enzyme is essential in prokaryotic sulfur-based energy
CC       metabolism, including sulfate/sulfite reducing organisms, sulfur-
CC       oxidizing bacteria, and organosulfonate reducers.
CC   -!- The system comprises the DsrAB reductase and the DsrL protein, which
CC       form a tight complex.
CC   -!- The reaction involves the small protein DsrC, which is present in all
CC       the organisms that contain dissimilatory sulfite reductase.
CC   -!- In sulfite reducers the DsrL component transfers two electrons from
CC       NADH to the DsrAB component, which then reduces the sulfur in sulfite
CC       to an S(II) intermediate that forms (together with two cysteine
CC       residues of DsrC) a trisulfide.
CC   -!- In sulfur oxidizers the enzyme catalyzes the opposite reaction.
CC   -!- Formerly EC 1.8.99.5.
DR   O33998, DSRA_ALLVD ;  Q59109, DSRA_ARCFU ;  Q59110, DSRB_ARCFU ;
DR   P94694, DSVB_MEGG1 ;  P45575, DSVB_NITV2 ;  P45573, DSVC_NITV2 ;
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