Gel-exclusion chromatography of solubilised MOMPs. A. GE analysis of C. trachomatis MOMP expressed in BL21omp8 cells with the OmpT leader, solubilised from an OM preparation in 1% (w/v) LDAO. Immuno-dotblots from successive 5 ml fractions between 100–220 ml (shown below the absorbance trace) reveal the appearance of high-molecular mass MOMP aggregates after the void volume, with a second immunoreactive peak at 195 ml (range 185–205 ml), corresponding to a molecular mass of 80 kDa (note inset column calibration trace, also in the presence of detergent). B. GE analysis of C. trachomatis MOMP expressed as in A but solubilised in 1% (w/v) Zwittergent 3–14. Oligomeric MOMP peaks at 180 ml (range 170–190 ml), corresponding to a molecular mass of 120 kDa. C. GE analysis of C. trachomatis MOMP in which all 9 cysteines were changed to alanine, expressed and solubilised as in B. Oligomeric MOMP peaks at 170 ml (range 160–190 ml), corresponding to a molecular mass of 160 kDa. Each trace is representative of at least 3 experiments.