Expected double-ring stoichiometries and sub-oligomeric fragments from them. LMR stands for the low mass ring, 4ClpP1 + 3ClpP2, and HMR stands for the high mass ring, 3ClpP1 + 4ClpP2. Relative ClpP1/P2 stoichiometries are given in square brackets. Experimental masses are given in round brackets. Question mark (?) indicates the fragments not recorded in the mass spectra.