The solution nanostructure of peptide assemblies with catalytic properties will be investigated using small-angle neutron scattering. This is a method to probe the structure and dimensions of nanoscale structures such as micelles and fibres formed by self-assembled molecules including peptides and molecules with attached lipid chains. By varying the composition of water and deuterium oxide (which is an isotopically labelled version of water, also known as heavy water) the neutron scattering power of the solution can be varied in order to highlight particular features of the molecule within the aggregates. We will use this method investigate the detailed inner structure of micelle and fibre self-assemblies formed by lipidated peptides with short peptide groups that have been shown to have activity as catalysts.