Hi -
My two cents:
First, you say:
I assume the bigger crystal might have lot of solvent which prevent
for high resolution. If it is true what could be the best way to
dehydrate crystal without affecting crystal quality?
I think this assumption is confusing. If the crystals were grown in
the same drop/condition, they have identical percentage solvent
content. Thus, you do not want to look at dehydration, the 'percentage
solvent content' is fine. What you want to look at is the mechanics of
vitrification. Big crystals, are simply hard to freeze: because of
their volume they cannot be vitrified as rapidly and uniformly as
smaller crystals. I will not be surprised if there are papers that
quantify that, but what I am saying here is only from experience and
adding a 'logical' explanation to that experience.
Thus, I would simply stay with the smaller crystals (I have a feeling
that you 'small' crystals are 'big' for many other people) and be
happy they diffract to 2.5 A (is that SR or RA?)
A.
On Apr 15, 2010, at 3:16, syed ibrahim wrote:
Dear Jurgen and Ho Leung
To add few more point regarding my question:
1. Crystal was first frozen in LN2 and then transfered to cryo
stream (in presence of LN2 in vial)
2. Anealing did not help (both short time and long time) - perhaps
the crystal dies.
3. Spots are clear to available resolution (is: 6-7A). In the high
resolution region there is no spot but looks like smear in the whole
area.
4. The crystal was approximately 1.0mm length and 0.4mm dia. I
mounted on 0.5mm loop. So the liquid around the crystal was very
less. I deliberately avoided more solvent in the loop to help
diffraction.
Thanks
Syed
--- On Thu, 4/15/10, Jürgen Bosch <jubo...@jhsph.edu> wrote:
From: Jürgen Bosch <jubo...@jhsph.edu>
Subject: Re: [ccp4bb] Cryo Vs crystal size
To: CCP4BB@JISCMAIL.AC.UK
Date: Thursday, April 15, 2010, 3:46 AM
There are a couple of additional factors not taken into account here.
1. LN2 versus frozen in strem or propane etc
2. did you try to flash anneal the larger crystal
3. smeary diffraction from the big crystal or not ?
4. how much residual solvent was around your crystal when freezing ?
In general smaller crystals are anyhow better in my hands.
Jürgen
On Apr 14, 2010, at 5:36 PM, syed ibrahim wrote:
Hi All
I had two crystals grown in same well, one is small and other is 10
times bigger. I treated both crystal in same cryo and same time.
The smaller one diffracted to 2.5A and the bigger one to 6-7A. I
was expecting the bigger one to diffract high resolution.
I assume the bigger crystal might have lot of solvent which prevent
for high resolution. If it is true what could be the best way to
dehydrate crystal without affecting crystal quality?
Thank you
Syed
PS: Taken care of less solvent to be present in the loop
-
Jürgen Bosch
Johns Hopkins Bloomberg School of Public Health
Department of Biochemistry & Molecular Biology
Johns Hopkins Malaria Research Institute
615 North Wolfe Street, W8708
Baltimore, MD 21205
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Department of Biochemistry (B8)
Netherlands Cancer Institute,
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