ID   1.8.99.5
DE   Dissimilatory sulfite reductase.
AN   Siroheme sulfite reductase.
CA   (1) Hydrogen sulfide + a [DsrC protein]-disulfide + 2 acceptor + 3 H(2)O
CA   = sulfite + a [DsrC protein]-dithiol + 2 reduced acceptor + 2 H(+).
CA   (2) A [DsrC protein]-S-sulfanyl-L-cysteine + 3 acceptor + 3 H(2)O =
CA   sulfite + a [DsrC protein]-disulfide + 3 reduced acceptor + 2 H(+).
CF   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   -!- In sulfur reducers it catalyzes the reduction of sulfite to sulfide,
CC       while in sulfur oxidizers it catalyzes the opposite reaction.
CC   -!- The reaction involves the small protein DsrC, which is present in all
CC       the organisms that contain dissimilatory sulfite reductase.
CC   -!- During the process an intramolecular disulfide bond is formed between
CC       two L-cysteine residues of DsrC.
CC   -!- This disulfide can be reduced by a number of proteins including DsrK
CC       and TcmB.
CC   -!- This enzyme is different from EC 1.8.1.2 and EC 1.8.7.1, which are
CC       involved in sulfate assimilation.
DR   O33998, DSRA_ALLVD ;  Q59109, DSRA_ARCFU ;  Q59110, DSRB_ARCFU ;
DR   P94694, DSVB_DESGG ;  P45575, DSVB_DESVH ;  P45573, DSVC_DESVH ;
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