Hi,
Just wondering if anyone has used the Cholesteryl hemisuccinte (CHS) tris salt before, more specifically with different detergents for membrane protein solubilisation? I have previously incorporated the non-salt form into DDM (which is an absolute nightmare to get in solution as you have to do it as a 10x solution and sonicate it continuously until it dissolves), but I've discovered that we have some of the tris salt form as well in the freezer, which is much easier to dissolve from what I understand. I know that this can be used with different detergents based on publications, but I've never managed to find out how they dissolved it - i.e was it dissolved directly in the detergents or in something else first as a stock then added?
The description from Anatrace doesn't really say much except that it's soluble to 1.2% in 6% CHAPS. Sigma also say that it is soluble in methanol to 1%. Preferentially though I would like to have neither of those near my membrane protein, especially as I will only be diluting by about 5 to 10x.
Although I'm asking this as a general question, I'm specifically thinking of using this CHS salt with Fos-choline 14. My thinking is that if CHAPS can dissolve it then FC14 should be able to as well, but thought it was worth asking before I potentially waste valuable resources!
Thanks.
Samuel.
I haven't used specifically that detergent mixture, but FC14 can solubilize it, since it is known as a pretty strong detergent. Just take care of the ratios (generally you need much more detergent than CHS)
Thanks Jorgaq Pata, that was the answer I was suspecting that I would get. I'm only going to be using the CHS at a final concentration of 0.15% with 1.5% FC14, so hoepfully it should dissolve fairly easily. I'm just about to make the detergent up, so I'll find out.
Samuel Davis just check the pH, because in function of pH the carboylate group will be negatively charged (or not), so this can change its affinity for H2O, thus its solubility
I'm dissolving in buffer with a pH of 8, so I'm assuming it should be fine based on previously using the non-salt form (which needs an alkaline pH).
Jorgaq Pata I added it and it appears to have dissolved. I accidentally added slightly too much of the salt (so the final conc was about 2.5% rather than 1.5%), but after 10 minutes of shaking on the mixer it seems to have gone into solution. Thanks for the help!
I noticed there will be some black precipitation after continuous sonication of CHS/detergent mixture solution. I was wondering if those black precipitation are some kind of degraded or maybe oxudized form of CHS. Do you know what those precipitation are?
Xiang Zhang I've sonicated CHS (both the Tris salt and the non-salt) into many different detergents with continuous sonication and not seen any sort of black precipiate before. Could your deterent or CHS powder stocks be contaminated in some way possibly?
Samuel Davis It is possible that those precipitate is impurity. But the amount of precipitate is large. I am wondering what kind of sonicator you are using. I use this sonicator (https://www.thomassci.com/Equipment/Ultrasonic-Cleaners/_/500-AND-750-WATT-ULTRASONIC-PROCESSORS?q=Ultrasonic%20Sonicator). And it produce a lot of heat during sonication. I guess heating might turn CHS into black precipitae.
Xiang Zhang I can't recall the exact sonicator that I previously used (it was about a year ago when I was at the University of Dundee that I last made detergent/CHS), but it was a probe sonicator about 30+ years old with a solid probe and little control except for intensity and a crude mechanical on/off cycler (which I don't think I ever used). The detergent/CHS solution did get very hot to the touch during the sonication, but that was necessary to be able to get it into solution. This particular sonicator was in a 4 degrees C cold room, but I doubt that made much difference.
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