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CATH Superfamily 3.30.70.20

The name of this superfamily has been modified since the most recent official CATH+ release (v4_4_0). At the point of the last release, this superfamily was: waiting to be named.

Functional Families

Overview of the Structural Clusters (SC) and Functional Families within this CATH Superfamily. Clusters with a representative structure are represented by a filled circle.
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FunFam 76: CoB--CoM heterodisulfide reductase iron-sulfur sub...

There are 2 EC terms in this cluster

Please note: EC annotations are assigned to the full protein sequence rather than individual protein domains. Since a given protein can contain multiple domains, it is possible that some of the annotations below come from additional domains that occur in the same protein, but have been classified elsewhere in CATH.

Note: The search results have been sorted with the annotations that are found most frequently at the top of the list. The results can be filtered by typing text into the search box at the top of the table.

EC Term Annotations Evidence
Ferredoxin:CoB-CoM heterodisulfide reductase. [EC: 1.8.7.3]
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM = 2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H(+).
  • HdrABC is an enzyme complex that is found in most methanogens and catalyzes the reduction of the CoB-CoM heterodisulfide back to CoB and CoM.
  • HdrA contains a FAD cofactor that acts as the entry point for electrons, which are transferred via HdrC to the HdrB catalytic subunit.
  • One form of the enzyme from Methanosarcina acetivorans (HdrA2B2C2) can also catalyze EC 1.8.98.4.
  • Cf. EC 1.8.98.5, EC 1.8.98.6, and EC 1.8.98.1.
 1 Q8TM02
Coenzyme F420:CoB-CoM heterodisulfide,ferredoxin reductase. [EC: 1.8.98.4]
2 oxidized coenzyme F420 + 2 reduced ferredoxin [iron-sulfur] cluster + CoB + CoM + 2 H(+) = 2 reduced coenzyme F420 + 2 oxidized ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB.
  • The enzyme, characterized from the archaeon Methanosarcina acetivorans, catalyzes the reduction of CoB-CoM heterodisulfide back to CoB and CoM.
  • The enzyme consists of three components, HdrA, HdrB and HdrC, all of which contain [4Fe-4S] clusters.
  • Electrons enter at HdrA, which also contains FAD, and are transferred via HdrC to the catalytic component, HdrB.
  • During methanogenesis from acetate the enzyme catalyzes the activity of EC 1.8.7.3.
  • However, it can also use electron bifurcation to direct electron pairs from reduced coenzyme F420 toward the reduction of both ferredoxin and CoB-CoM heterodisulfide.
  • This activity is proposed to take place during Fe(III)-dependent anaerobic methane oxidation.
  • Cf. EC 1.8.98.5, EC 1.8.98.6, and EC 1.8.98.1.
 1 Q8TM02
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