This domain is found at the C-terminal end of the FAD-linked sulfhydryl oxidase R596 from Acanthamoeba polyphaga mimivirus (APMV) and similar proteins predominantly found in giant viruses. This protein is a member of the Erv family of sulfhydryl oxidases. This is an ORFan domain that folds into six alpha-helices forming a compact domain [1].

1: Exploring ORFan domains in giant viruses: structure of mimivirus sulfhydryl oxidase R596. Hakim M, Ezerina D, Alon A, Vonshak O, Fass D; PLoS One. 2012;7:e50649. PMID:23209798