PFOR_II is a core domain of the anaerobic enzyme pyruvate:ferredoxin oxidoreductase and is necessary for inter subunit contacts in conjunction with domains I and IV [1,2].

1: Crystal structures of the key anaerobic enzyme pyruvate:ferredoxin oxidoreductase, free and in complex with pyruvate. Chabriere E, Charon MH, Volbeda A, Pieulle L, Hatchikian EC, Fontecilla-Camps JC; Nat Struct Biol 1999;6:182-190. PMID:10048931

2: Identification and characterization of oxalate oxidoreductase, a novel thiamine pyrophosphate-dependent 2-oxoacid oxidoreductase that enables anaerobic growth on oxalate. Pierce E, Becker DF, Ragsdale SW; J Biol Chem. 2010;285:40515-40524. PMID:20956531