Re: [ccp4bb] Crystals grown from high ammonium sulphate

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CCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999

Previous message:
Subject: Re: Crystals grown from high ammonium sulphate
From: Iain Kerr ikerr {- at -} CMP {- dot -} UCSF {- dot -} EDU
Date: 2008-11-04

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Subject: Re: tricoordinated ion?
From: "Borhani, David" David {- dot -} Borhani {- at -} DESHAWRESEARCH {- dot -} COM
Date: 2008-11-04

Subject: Re: Crystals grown from high ammonium sulphate
From: Tim Gruene tg {- at -} SHELX {- dot -} UNI-AC {- dot -} GWDG {- dot -} DE
Date: 2008-11-04

Generally crystals require a much higher precipitant concentration for
nucleation than for growth and maybe even less for maintenance of their
crystalline state.

Therefore I would
a) try micro seeding into less Ammonium Sulpahte
b) reduce the ammonium sulfate concentration in the drop by adding
ammonium sulphate free mother liquor to the reservoir (not the drop
itself!) This would re-equilibrate the drop to lower a AS
concentration. You could remove one crytal and try to find the lowest
possible AS concentration with it separately.

Tim

--
Tim Gruene
Institut fuer anorganische Chemie
Tammannstr. 4
D-37077 Goettingen

GPG Key ID = A46BEE1A

On Tue, 4 Nov 2008, Sabine Schneider wrote:

> Hi everyone,
>
> We got crystals that grew in ~3.2M ammonium sulphate and some tris-buffer at
> 18dgC. Unfortunately the crystals take a while to grow (~4-5 weeks) and so
> far we only have 4-5 xtals.
> I tried to freeze the crystals, but as soon as I broke though the skin of the
> drop the ammonium sulphate started to crystallise. I got the crystals out,
> froze them using sort of an artifical mother liquor with sodium malonate as
> cryo and tested the diffraction. The freezing seems to be OK and it is
> definitely a protein crystal. The crystal suffered when the ammonium sulphate
> in the drop started to crystallise, but didn't seem to deteriorate anymore in
> the cryo. Well the corners had already more or less disappeared by the time I
> got them out of the drop...
> Since we only have a few xtals at the moment and I can't try out a lot of
> things, I was wondering if anyone has experienced and solved a similar
> problem? My freezing attempt so far was in an airconditioned room with 18dgC.
> I thought about higher humidity and temperature in the room, and/or adding
> the cryo directly to the drop.... Any ideas are very much appreciated!
>
> Sabine
>
> ------------------------------------------
> Dr. Sabine Schneider
> Ludwig-Maximilians-University
> Department of Chemistry and Pharmacy
> Butenandtstrasse 5-13, Building F
> 81377 Munich
> Germany
> Phone: +49 (0)89 2180 77846
> Fax: +49 (0)89 2180 77756
> http://www.carellgroup.de/
>

CCP4bb navigation

CCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999

Previous message:
Subject: Re: Crystals grown from high ammonium sulphate
From: Iain Kerr ikerr {- at -} CMP {- dot -} UCSF {- dot -} EDU
Date: 2008-11-04

Next message:
Subject: Re: tricoordinated ion?
From: "Borhani, David" David {- dot -} Borhani {- at -} DESHAWRESEARCH {- dot -} COM
Date: 2008-11-04