HELP! Extraction of periplasmic proteins.

[schupp at nauvax.ucc.nau.edu]

Alex,
        You might try polymyxin B sulfate, a strongly cationic antibiotic.  It
has been shown to disrupt the outer membrane of gram- bacteria.  I use it to
perforate cells prior to a luciferase assay at a concentration of 12.5ug/ml final.  The disruption is almost instantaneous at room temp.  I can't say whether this will selectively release periplasmic proteins while retaining intracellular
ones.  You might try a range of concentrations and compare the extraction p
protein profiles.  Papers by Donohue-Rolfe (Infect. Immun.  39:270-274, 1983)
and Griffin (Infect. Immun.  40:425-428, 1983) suggest that periplasmic
proteins can be selectively released by polymyxin B and osmotic shock.

Jim Schupp