Lipopolysaccharide interferes with the staining of lipoprotein on polyacrylamide gels.

After electrophoresis of total membrane preparations of Escherichia coli B on sodium dodecyl sulfate polyacrylamide gels, and subsequent staining with Coomassie Brilliant blue, a band corresponding to the Braun lipoprotein fails to appear. This is in contrast to similar preparations of E. coli K-12 which do display the lipoprotein upon staining. Experiments described below indicate that failure to observe this protein in E. coli B is due to interference in the staining reaction by the lipopolysaccharide present in the membrane preparations.