Abstract
The sensitivity of the outer and cytoplasmic membranes of Escherichia coli to detergent was examined by isopycnic sucrose density gradient centrifugation. Sodium lauryl sarcosinate (Sarkosyl) was found to disrupt the cytoplasmic membrane selectively under conditions in which Triton X-100 and dodecyl sodium sulfate solubilized all membrane protein. These results were verified by gel electrophoresis; membrane proteins solubilized by Sarkosyl were identical to those of the cytoplasmic membrane. The presence of Mg(2+) during treatment with Sarkosyl was found to afford partial protection of the cytoplasmic membrane from dissolution.