Thaw a cell pellet corresponding to 1L culture by re-suspending it in 40 ml lysis buffer (50 mM HEPES pH 7.5, 300 mM NaCl, 1 mM MgCl2, 10% glycerol, 0.5% CHAPS, 5 U/ml Benzonase (Sigma), 1 mM DTT, CIP protease inhibitor (Sigma), cOmplete EDTA-free protease inhibitor cocktail (Roche)) and rolling or stirring in the cold room.