Need help with GST fusion protein purification

[Dr E. Buxbaum]

If everything else fails, forget about your tag and do conventional 
protein purification. I was in that situation once when a MBP-conjugate 
absolutely refused to bind to the affinity column. 

Ammoniumsulfate fractionisation, gel chromatography and ion exchange 
chromatography gave me a pure product and a good yield. Not very elegant, 
but it worked.