Re: [ccp4bb] "Quick soak" method

- Protein crystallography

Main steps:

- Protein purification
- Crystallisation

Special:

- Programs for crystallography
- X-ray detectors

Basic tutorials:

   - Chemistry
   - Protein
   - Peptide
   - Amino Acids

Xtal community:

- CCP4BB

CCP4bb navigation

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

Previous message:
Subject: Re: "Quick soak" method
From: Jacob Keller j-keller2 {- at -} MD {- dot -} NORTHWESTERN {- dot -} EDU
Date: 2007-09-25

Next message:
Subject: Re: "Quick soak" method
From: Dirk Kostrewa kostrewa {- at -} LMB {- dot -} UNI-MUENCHEN {- dot -} DE
Date: 2007-09-26

Subject: Re: "Quick soak" method
From: Uwe Mueller umue {- at -} BESSY {- dot -} DE
Date: 2007-09-26

Dear Derek and Tassos,
I normally start using the following compounds depending on pH of the
cryo-solution at 10 mM concentration and 10 min incubation time and
optimize towards lower concentrations and longer incubation times:
-ethyl mercuric phosphate (EMP)
-HgCl2
-SmCl3
-K2PtCl4
-K2PtCl6

Best regards,
Uwe

Derek Logan schrieb:
> Hi Uwe,
>
> Just what I wanted to hear, and with a limited set of compounds too!
> Follow-up question: what are these 4-6 most successful compounds?
> Thanks also for the tips on monitoring thw soaking
>
> Derek
>
> On Sep 25, 2007, at 13:23, Uwe Mueller wrote:
>
>> Dear Derek,
>> we are using the quick-soak method frequently at the BESSY-MX
>> beamlines. So far we were able to obtain phase information in terms
>> of MAD/SAD- phases in all cases which we tried. The starting set-up
>> is the screen over the 4-6 most successful heavy atom compounds at
>> 5-10mM concentration and 10-20 min soaking time.
>> If you follow the soaking under a transmissive light microscope like
>> the Leica MZ7.5, you can receive quite intriguing visual feedbacks
>> from your experimental set-up, including the bending of large crystal
>> face areas towards the crystal center due to the large osmotic
>> pressure at the beginning of the process an others. Those
>> observations might provide you further information for the
>> optimization loop which will be confirmed by the detection of an
>> anomalous signal after the peak-dataset.
>> 3-8 of such fast feedback loops could be carried out within a 8h
>> beamtime shift and led to interpretable electron densities. So, I
>> regard this method as a very powerful alternative, where the
>> availability of SeMet-crystals is limited.
>>
>> Best regards,
>> Uwe
>>
>>
>> Derek Logan schrieb:
>>> Hi,
>>>
>>> I'd like to find out how successful the "quick soak" method for
>>> heavy atom derivatisation proposed by Radaev and Sun:
>>>
>>> Sun PD, Radaev S, Kattah M. Generating isomorphous heavy-atom
>>> derivatives by a quick-soak method. Part I: test cases. Acta Cryst.
>>> 2002. D58:1092-1098.
>>>
>>> has been in comparison to the "classical" method of longer soaks at
>>> low concentrations of heavy atom compound. The method was quite
>>> successful in our hands a few years ago but (fortunately?) it's
>>> becoming increasingly rare that we use heavy atoms. I understand
>>> that evidence will necessarily be anecdotal, but let's not let that
>>> stop us.
>>>
>>> Derek
>>> --
>>>
>>> Derek Logan tel: +46 46 222 1443
>>>
>>> Associate professor fax: +46 46 222 4692
>>>
>>> Molecular Biophysics mob: +46 76 8585 707
>>> Lund University
>>>
>>> Box 124, Lund, Sweden
>>>
>>>
>>>
>>
>> --
>> _______________________________
>>
>> Dr. Uwe Müller
>> BESSY-MX group BESSY GmbH
>> Albert-Einstein-Straße-15
>> D-12489 Berlin
>> Phone: +49-(0)30-6392 4974
>> Fax : +49-(0)30-6392 4975
>> email: umue@bessy.de
>> url : http://www.psf.bessy.de
>>
>> BESSY GmbH - Mitglied der Leibniz Gemeinschaft
>> Vorsitzender des Aufsichtsrates: Prof. Dr. Dr. h.c. mult Joachim Treusch
>> Geschäftsführer: Prof. Dr. Dr. h.c. Wolfgang Eberhardt, Prof.
>> Dr.Eberhard Jaeschke Sitz Berlin, AG Charlottenburg, HRB 14635

--
_______________________________

Dr. Uwe Müller
BESSY-MX group

BESSY GmbH
Albert-Einstein-Straße-15
D-12489 Berlin

Phone: +49-(0)30-6392 4974
Fax : +49-(0)30-6392 4975
email: umue@bessy.de
url : http://www.psf.bessy.de

BESSY GmbH - Mitglied der Leibniz Gemeinschaft
Vorsitzender des Aufsichtsrates: Prof. Dr. Dr. h.c. mult Joachim Treusch
Geschäftsführer: Prof. Dr. Dr. h.c. Wolfgang Eberhardt, Prof. Dr.Eberhard Jaeschke
Sitz Berlin, AG Charlottenburg, HRB 14635

CCP4bb navigation

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

Previous message:
Subject: Re: "Quick soak" method
From: Jacob Keller j-keller2 {- at -} MD {- dot -} NORTHWESTERN {- dot -} EDU
Date: 2007-09-25

Next message:
Subject: Re: "Quick soak" method
From: Dirk Kostrewa kostrewa {- at -} LMB {- dot -} UNI-MUENCHEN {- dot -} DE
Date: 2007-09-26