What's a non-toxic and safe alternative to ammonium sulphate precipitation?

Question

I'm trying to isolate albumin in egg whites and I was told to further separate it with ammonium sulphate. However, I heard that it was toxic to use, so is there an alternative?

Answer 1

Are you trying to ISOLATE or PURIFY the albumin?  If you simply want to isolate it (along with some of the other soluble proteins in egg whites), then you can add water to the egg whites to precipitate the globular proteins, filter, and isolate the ablumins in the filtrate.  If you want to further purity the albumin, then theoretically any salt at high enough ionic strength will precipitate (salt out) the albumin. However, your concerns with ammonium sulfate (the most commonly used agent for such a procedure) may not be completely justified. It takes a fair amount of this salt to cause human toxicity, and further, you can remove the ammonium sulfate following isolation and purification of the albumin.  After purification by salting out, you simple filter or centrifuge the preparation, and resuspend the albumin in water, or some desired buffer, etc.