Hi Anamika,

    As it was said before, a cocktail of protease inhibitors should be fine. But let`s say you can not overcome the problem. It is not specified if you are doing this dialysis to cleave or not your His-tagged protein but even this you could try getting samples in 1 hour intervals then you could monitor the stability (and/or cleavage) of your protein. Another thing is if you are doing this at room temperature or at 4C.

    Best regards,

    Everton.

On Thu, Oct 26, 2017 at 5:11 PM, Smith Liu <[log in to unmask]> wrote:
suppose protease is the issue, then avoid overnight dialysis


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在2017年10月26日 22:18，Anamika Singh 写道：
Dear All,

I am purifying the His-tagged proteins ( 21Kda) using buffer 20mM Tris, 150mM Nacl, and 5mM MgCl2 with 500mM imidazole. Earlier I was facing the precipitation problem during dialysis but with the addition of 50mM L-Arg somehow managed to overcome the precipitation issue. But this time I have seen after overnight dialysis there are degradation products on SDS page. I have used protease inhibitor (PMSF) in my sonication buffer. 

Please suggest me to overcome this problem. 

Thanks
--
Anamika





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Éverton Dias D'Andréa