Re: [ccp4bb] is it Ok to freeze

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

Previous message:
Subject: Re: is it Ok to freeze
From: Remy Loris reloris {- at -} VUB {- dot -} AC {- dot -} BE
Date: 2008-06-19

Next message:
Subject: Re: is it Ok to freeze
From: Marius Schmidt marius {- dot -} schmidt {- at -} PH {- dot -} TUM {- dot -} DE
Date: 2008-06-19

Subject: Re: is it Ok to freeze
From: harry powell harry {- at -} MRC-LMB {- dot -} CAM {- dot -} AC {- dot -} UK
Date: 2008-06-19

Hi

Without wishing to start an argument, I've been checking with some of
my colleagues who are chemical crystallographers - the reply I get is
that, for routine structural analysis, "pretty well all datasets are
collected at 100K unless the crystals fall apart at low T, or if the
cryostream is broken".

I should point out that the first production Cryostream that I came
across (serial number 2, which I think may have been the first one
sold!) was in the Cambridge Department of Chemistry in about 1985.
They didn't become common until the mid-1990's in PX labs, when they
were already well-established as a bit of pretty well essential kit
for small molecule work.

So although what Remy says is true, the practice is to cryocool most
of the time.

On 19 Jun 2008, at 12:08, Remy Loris wrote:

> Typically crystals of small organic compounds do not require
> freezing as there are no solvent channels. They do in general not
> suffer from radiation damage at room temperature the way protein
> crystals do. Occasionally they are mounted in a capillary instead
> of simply glueing them to a goniometer if they are air sensitive.
> In principle freezing should not damage the crystals, but one still
> may have to be carefull if the crystals are large. I think you risk
> increasing mosiacity, and any manipulation that is not needed will
> on average only reduce the quality of the specimen rather than
> improve it
>
> Remy Loris
> Vrije Univesiteit Brussel
>
> Jayashankar wrote:
>> Dear Scientists and Friends,
>> I am not sure, whether organic crystals need to be in cryo
>> stream necessarily during data collection from an in house
>> xray machine .
>> How most of the organic crystals have been solved mostly?
>> --
>> S.Jayashankar
>> (A bit confused new generation researcher).
>> Research Student
>> Institute for Biophysical Chemistry
>> Hannover Medical School
>> Germany

Harry
--
Dr Harry Powell, MRC Laboratory of Molecular Biology, MRC Centre,
Hills Road, Cambridge, CB2 2QH

CCP4bb navigation

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

Previous message:
Subject: Re: is it Ok to freeze
From: Remy Loris reloris {- at -} VUB {- dot -} AC {- dot -} BE
Date: 2008-06-19

Next message:
Subject: Re: is it Ok to freeze
From: Marius Schmidt marius {- dot -} schmidt {- at -} PH {- dot -} TUM {- dot -} DE
Date: 2008-06-19