What to add to centrifuge tube
Posted 20 March 2010 - 09:09 PM
Posted 21 March 2010 - 04:38 AM
What are you trying to do?
If you are doing an ammonium sulfate precipitation, you are adding salt, precipitating protein, adding more salt, precipitating protein, etc. You are doing a quick purification of your protein which will precipitate when the salt reaches a certain percentage. The cool thing here is that your protein isn't denatured and when salts are removed, your protein goes back into solution and is still soluble. Then you can further purify it or use it as is depending on what you're doing. Here's a few links with detailed explanations:
Protein Precipitation Using Ammonium Sulfate
1National Institutes of Health, Bethesda, Maryland
Current Protocols in Protein Science
Online Posting Date:
Check your PM
Edited by Denny, 21 March 2010 - 04:43 AM.
Posted 21 March 2010 - 08:04 AM
I now think the salt is added to insolubilise (salt out) some soluble proteins so that the supernatant will contain purer target protein.
Posted 14 April 2010 - 12:01 PM
the salint point is: ammonium sulfate robs proteins the covering water to precipitate WITHOUT denaturation
Posted 05 June 2010 - 03:09 PM
If you're still trying to salt the protein out of solution just make sure you add the AS slowly with gentle stirring with your protein on ice. I didn't check out the link to the protocol Denny posted, but it should mention those details if it didn't. Adding the AS slowly just prevents locally high concentrations of AS, which could prompt some of your target protein to fall out even as the percent AS is below the threshold for your protein. Sorry if you already knew about this, though.