Protein Purification Problem

Jonathan Kurtis, MD/PhD Jonathan_Kurtis at
Tue Dec 12 13:05:39 EST 2000

Hi all,

I have purified a recombinant fusion protein which contains 1167 aa with a
calculated Mw of 118 kDa. I intend to cut this fusion protein with Factor
Xa protease into the fusion partner (619 aa, 53 kDa, pI=5.95) and the
protein of interest (548 aa, 65 kDa, pI= 6.18). 

These fragments differ in size by only 20% and in pI by 0.23 units. There
are no affinity tags on the fragments.

Using a starting material of 500ug/ml, should it be possible to separate
them by ion exchange (merits of anion vs cation??) ?? by size-exclusion

I need to purify approximately 25 mg.

Thanks for your help,

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