I also solved a structure on our home CuKa source by SIRAS with 20-60sec in 0.5-1M KI.
JPK
==============Original message text===============
On Tue, 25 Sep 2007 6:55:28 pm CDT James Whisstock wrote:
Hi - sorry - rather than iodine I meant to say we had had success with Potassium Iodide (1M for 20
seconds)!
Cheers
James
[log in to unmask] wrote:>
> Hi,
>
> I do not use their method as such - however, I love heavy atom soaks and
> do them any time I can, so I've got very similar experiences in the past.
>
> Heavy atoms can bind very quickly even from quite dilute solutions - the
> quickest I've ever soaked (and got useful data) was sodium
> chloroplatinate
> in under ten minutes at ~ 1mM concentration. The next quickest was
> K2Pt(NO2)4 which tends to take between 10 minutes and 30 minutes, almost
> regardless of the concentration. This is by far my favorite HAD reagent,
> incidentally.
>
> In general my soaks are all less than one hour with a few exceptions,
> such
> as iodine [not iodide!] soak to iodinate tyrosines which is typically
> better done during a day or so with very low amount of I2, via vapor
> phase.
>
> Artem
>
>> 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
>>
>>
>>
--
Professor James Whisstock
NHMRC Principal Research Fellow / Monash University Senior Logan fellow
Department of Biochemistry and Molecular Biology
Monash University, Clayton Campus, PO Box 13d, VIC, 3800, Australia
+613 9905 3747 (Phone)
+613 9905 4699 (Fax)
+61 418 170 585 (Mobile)
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Jacob Keller
Northwestern University
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