Proteins in this family are thought to be cyclase enzymes. They are found in proteins involved in antibiotic synthesis. However they are also found in organisms that do not make antibiotics pointing to a wider role for these proteins. The proteins contain a conserved motif HXGTHXDXPXH that is likely to form part of the active site.

1: The Streptomyces peucetius dpsY and dnrX genes govern early and late steps of daunorubicin and doxorubicin biosynthesis. Lomovskaya N, Doi-Katayama Y, Filippini S, Nastro C, Fonstein L, Gallo M, Colombo AL, Hutchinson CR; J Bacteriol. 1998;180:2379-2386. PMID:9573189