Soluble protien of GST - (May/02/2013 )

Hi there,
I have cloned my gene of interest into pGEX-2T vector. I have indue it with IPTG for different concentration and different temprature different competant cells (my cell BL21 ) but usually it become insoluble. I am using thermo kit for purification, however I used Sarkosyl but i have got promssing but protien.
Please If you have any method to soluble my protien without effect the protien I will use it for Histone Methyltransferase - Assay

any help

you can solubilize it in urea and then refold after purification by slowly dialyzing away the urea.