Re: [ccp4bb] heavyatom soaking problem

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

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Subject: packing
From: Tassos Papageorgiou apapageo {- at -} BTK {- dot -} UTU {- dot -} FI
Date: 2007-06-29

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From: Wim Burmeister wpb {- at -} EMBL-GRENOBLE {- dot -} FR
Date: 2007-06-29

Subject: Re: heavyatom soaking problem
From: Tommi Kajander tommi {- dot -} kajander {- at -} HELSINKI {- dot -} FI
Date: 2007-06-29

Quoting Priyank Maindola :

> Hello all,
> I am struggling with getting the phases out for my protein. Heavyatom
> database shows that only mercury and samarium have the binding motifs in
> it.
>
> Sodium iodide soak is killing the crystal even as less as 0.2 Molar
> concentration for 30sec.
> With Potassium iodide crystal is okay upto 0.75M for 1 & a half min but
> the
> incorporation is not at relevent sites.(Iodide signal is not distinct and
>
> is weak)

how much data and what is anomalous redundancy? what space group?
could you do Sulphur-SAD?

> Hg & Au salts precipitate it.

i dont understand this, precipitate the crystals?
what concentrations and soak times do you use and what is the pH?

...ie more details would be useful.

> With Pt signal is weak.

again how about a longer soak??? higher concentration???
... or try Pd, should be more reactive.

> Somewhere I read that high salt causes problems for heavy atom to bind to
>
> protein.My protein needs high salt for stability (750mM NaCl)

I think that would mainyl affect electrostatic binding, but imidazole
of cys attachement of Hg, Pr etc probably not. (??????)

and again, why no se-met??????

> Please help with some suggestion!!
>

tommi

CCP4bb navigation

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

Previous message:
Subject: packing
From: Tassos Papageorgiou apapageo {- at -} BTK {- dot -} UTU {- dot -} FI
Date: 2007-06-29

Next message:
Subject: Re: packing
From: Wim Burmeister wpb {- at -} EMBL-GRENOBLE {- dot -} FR
Date: 2007-06-29