The proteasome activating complex (PAN) is an archaebacterial homologue to unfoldases involved in the regulation of the eukaryotic proteasome (one of the molecular machines that control protein degradation in living cells). The correct regulation of protein degradation is of paramount importance for the biological cell and in particular for the aging process. A dysfunction of protein degradation (proteolysis) can seriously impair cellular function and in extreme cases lead to cancer and neurodegenerative diseases. The presentSANS proposal aims at studying the conformation of PAN and a substrate, green fluorescent protein (GFP), by using contrast variation to focus on either of the two partners during the unfolding event. This proposal is the last one in the series for the ILL PhD project of Ziad Ibrahim. It will complement the dyamic ones already granted by arresting the PAN-GFP complex by attaching Avidin at the C-terminus of GFP which will allow a sophisticated rigid-body modelling of the complex.