HELP! Extraction of periplasmic proteins.

[Alexander V Kravchuk]

 Sorry if this is the wrong place to ask the question below!

 What is a good method of extraction of periplasmic proteins,
overexpressed in E.coli? The method I am using now (osmotic shock)
does not look very efficient: either I get a lot of intracellular
proteins in the extract, or barely get any protein at all if I try
to do it more gently.

 If you know better method and/or can direct me to one, please
reply via e-mail.

 Thank you very much in advance!

 Alex.