how to purify fusion proteins on a large scale? - (Jul/03/2006 )

hello everybody

can anyone please give me information about how to purify fusion proteins on a large scale?
i want to understand also how to determine which OD to start my IPTG induction in? and when to say its time to stop when OD reaches 2???
any sites talking about this?
thankx in advance

hi again
sorry i found a topic in the forum the same as mine....

anyone knows the size of fusion protein (GST-EGFP)?