The caseinolytic protease from E. coli is comprised of two subunits: the protease, ClpP, and the ATPase, ClpA. Fully active ClpP has been over-expressed in E. coli and purified to homogeneity. Mass measurements from the STEM indicate that it is a tetradecamer. In stain, it appears as two stacked seven-member rings. Small angle X-ray and neutron scattering curves were determined for ClpP in solution. A model was derived from these data of a cylinder with an axial pore. The size of the pore is similar to that found in chaperone proteins. Similar studies will be performed using the STEM on ClpA alone, both from E. coli and from plants. The ClpA component may be hexameric. The final goal is to look at the interaction of ClpP and ClpA.