Hi Anna,
Actually I just tried lithium sulfate: I made a cryo with 1M KCl, 1.3M Lithium
sulfate to replace the ammonia sulfate totally at pH7. it is not freezing
clear. I guess I should try to increase the amount of LiSO4. But from all the
warm responses here, I found sometimes people don't necessary keep the same
concentration of component in the cryo as in the well solution +
cryoprotectant. I usually make the artificial mother liquor as Roger or Michael
mentioned early on. So my question is: will that hurt the crystal if the
concentration of the component of cryo change?
Want to thanks to all for your warm suggestions. I haven't finish all the
reading suggested here. but will.
Thanks,Manqing
Date: Thu, 12 Jul 2012 13:40:39 -0700
From: anna.s.gardb...@gmail.com
Subject: Re: [ccp4bb] cryo for high salt crystal
To: CCP4BB@JISCMAIL.AC.UK
Hello, Min.Lithium sulfate is a cryoprotectant at 2.0 M and sometimes even less
(much lower than the concentrations needed for ammonium sulfate), so I would
try replacing your ammonium sulfate with lithium sulfate, creating a
cryoprotectant with 0.5-1.0 M KCl, 1.4-2.0 M LiSO4, at pH 7. You might need to
transfer your crystals through a couple of intermediate drops.
Regarding the reservoir precipitation - is there any chance you could control
the humidity of the area in which you're working? Even filling a couple of
adjacent reservoirs with water might help buy you a few extra crucial seconds.
Also, working in a cold room to harvest your crystals will help reduce the
evaporation rate.
Good luck!
Best,Anna
On Tue, Jul 10, 2012 at 9:28 AM, m zhang <mzhang...@hotmail.com> wrote:
regaentDear All,
I am sure this question was discussed before. But I am wondering if anyone got
the same experience as I do. I got a crystal out of condition with 1M KCl, 1.4M
Ammonium sulfate at pH7. I tried to use glycerol, ethylene glycol, 25% sucrose,
paraton-N oil, or ammonium sulfate itself: The problem is that all the cryo
plus original reagents in the reservoir precipitate the salts out. And more
serious problem is because of high salt in the condition, while I am trying to
loop the crystal, both the drop and cryoprotectant drop form salt crystals (not
sure it is KCl or ammonia sulfate) significantly and very quickly, that cause
my crystal dissolved. My crystal doesn't seem to survive paraton-N oil. Does
anyone here have similiar case? any suggestion will be appreciated.
Thanks,Min
