Ammonium Sulphate ppt + His Tags

Randy Willis willis at
Thu Apr 24 15:52:26 EST 1997


In the past, with an unknown protein, I have always performed amm.sulf.
cuts in increments of 10%.  If using solid salt, make sure that you drop
the salt into your solution very slowly with steady, but not too violent
mixing.  You can find a chart of amounts to add in almost any protein
purification text.  If using a solution of amm.sulf., I have found that
a 4M solution is saturated at 4C (ie not all of it goes into solution). 
Remember to account for volume changes when adding the sat.solution to
your protein solution.  Between additions of salt, allowing several
minutes to half an hour or so, centrifuge your protein slurry at about
10-20000 rpm for 30' or more, separate the pellet and solution (should
be very little salt in pellet) and continue to saturate your

Good luck,

Randall C Willis, Researcher
Biochemistry, Hosp for Sick Children
3522-555 University Ave
Toronto, ON

416-813-5933 (ph)  -5022 (fax)

willis at

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