Lots of protein remains bound to the matrix even after elution with buffer containing 500mM Imidazole.
If 0.5 M is not enough, try to change pH. To increase above 0.5 M is not effective
What buffer condition are you currently using? You could for example increase the NaCl concentration in case your protein is sticking unspecifically to the column matrix.
2 M imidazole in 500 mm NaCl should be fine. Make sure to adjust the pH of your final buffer.
Can anybody suggest a spectrophotometric method for detecting the presence of selenocysteine in a protein sample?
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