The structural role of the zinc ion can be dispensable in prokaryotic zinc-finger domains, Baglivo, I., Russo L., Esposito S., Malgieri G., Renda M., Salluzzo Antonio, Di Blasio B., Isernia C., Fattorusso R., and Pedone P.V. , Proceedings of the National Academy of Sciences of the United States of America, Volume 106, Number 17, p.6933-6938, (2009)