ABSTRACT Cupin proteins share a double-stranded β-helix fold, form one of the largest superfamilies and possess remarkable functional diversity. They usually form homooligomeric states. Michailidou et al. recently reported that a cupin protein Pac13, which is a dehydratase mediating the formation of the 3’-deoxy nucleoside of pacidamycins, is an unusual, small monomer. However, a careful analysis of the biophysical and structural data provided by the authors clearly indicates that Pac13 is a homodimer.