Gram negative bacteria cause a wide range of diseases. Colicins are protein toxins capable of penetrating the outer membrane barrier and killing the bacteria. Thus they constitute an untapped source of antibiotics. We wish to resolve the structure of colicins bound to their outer membrane receptor and one complex, representing the secondary, membrane penetrating stage has already been resolved by the use of deuterated SDS detergent. 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. The previous two days on SANS2D have shown that we can use d/h octylglucoside and we have clear data for two of 4 contrasts. The trickier 87%/100% D2O samples need to be run and for publication we must extend the 16% D2O data. This is a continuation to complete this important study.