Purothionins are a family of cationic cystiene rich plant defence proteins which have been shown to have a wide spectrum of activity due their ability to permeate cellular membranes. Here we intend to examine the interaction of beta-purothionin with floating lipid bilayers of DPPG and DPPC to roughly model the bacterial and eukaryotic membranes respectively. We will use the floating bilayer model and neutron reflectometry to examine how this protein self assembles into pore structures across the membrane. This activity of the protein will be monitored both strucuturally and kinetically using advances in instrument capabilities at ISIS. Comparisons between the data obtained from this study with previous NR data obtained on related though more selective plant defence proteins will allow for a greater understanding of the behaviour of this protein group at the membrane interface.