Gram negative bacteria cause a wide range of diseases including meningitis, bubonic plague, gonorrhoea, diarrhoea, Legionnaires' disease and cholera. Their outer membrane provides them with their characteristic impermeable outer shell. Colicins are protein toxins capable of penetrating this barrier and killing the bacteria. Thus they constitute an untapped source of antibiotics. We are interested in resolving the structure of colicins bound to their outer membrane receptor and one complex representing the secondary, membrane penetrating stage has has already been resolved by the use of deuterated SDS detergent and hydrogenous/deuterated protein components. The SDS imitates LPS and partially unfolds the colicin. In this proposal we wish to build on this work by solving the initial binding structure of colicin N bound to OmpF which we will trap in the presence of non-ionic detergents.