how to improve the gst protein purification? - (Mar/25/2008 )

hi, what's the purity you can get from the gst protein purificaton? i am using the Glutathione Sepharose™ beads from the GE HEALTH, but i only got 50% pure. i have heard that the Glutathione Sepharose FF column is better . i need the protein to be 90% pure. my boss tell me to do another gel filtration if the purity is not good from the affinity purification. but i hope i can find a way to purify it in one step. what's the method that you suggest?
thanks
jennfer

i suggest you listen to your boss and add the gel filtration step after the affinity step.

but, if you don't, try eluting with a gradient. see where your protein is released then work out a step gradient (or stay with a linear gradient if necessary).