Members of this family are the enzyme capreomycidine synthase, which performs the second of two steps in the biosynthesis of 2S,3R-capreomycidine from arginine. Capreomycidine is an unusual amino acid used by non-ribosomal peptide synthases (NRPS) to make the tuberactinomycin class of peptide antibiotic. The best characterized member is VioD from the biosynthetic pathway for viomycin. [Cellular processes, Biosynthesis of natural products]