Move the beam stop back? My lab has grown quite a few
crystals that only diffract to very low resolution.
Phoebe (with sympathy!)
---- Original message ----
>Date: Mon, 19 Apr 2010 11:35:11 +0800
>From: tat cheung cheng <[log in to unmask]>
>Subject: [ccp4bb] Re: [ccp4bb] Mysterious Crystals?
>To: [log in to unmask]
>
> Thank you. Forget to mention, no diffraction
> observed no matter with or without cyro cooling.
>
> ------------------------------------------------
>
> 寄件人﹕ "[log in to unmask]" <[log in to unmask]>
> 收件人﹕ [log in to unmask]
> 傳送日期﹕ 2010/4/19 (一) 11:29:38 AM
> 主題: RE: [ccp4bb] Re: [ccp4bb] Mysterious
> Crystals?
>
> Hello Tc,
>
>
>
> It isn’t that unusual to get protein crystals that
> don’t diffract. This happens probably 50% of the
> time. One can try dehydration of the crystals,
> crystal annealing and additive screens to see if any
> of these things will give you some diffraction. In
> addition, you didn’t mention whether you froze
> these crystals- one should also try putting a
> crystal in the beam without cryo-cooling, as
> cryo-cooling can often be detrimental to
> diffraction.
>
>
>
> Cheers, tom
>
>
>
> ----------------------------------------------------
>
> From: CCP4 bulletin board
> [mailto:[log in to unmask]] On Behalf Of tat
> cheung cheng
> Sent: Monday, 19 April 2010 1:26 PM
> To: [log in to unmask]
> Subject: [ccp4bb] Re: [ccp4bb] Mysterious
> Crystals?
>
>
>
> Yes, I have just done that. They are protein. But if
> they are protein, why no diffraction? That's
> intriguing.
>
>
>
> ----------------------------------------------------
>
> 寄件人﹕ Jürgen Bosch <[log in to unmask]>
> 收件人﹕ [log in to unmask]
> 傳送日期﹕ 2010/4/19 (一) 10:57:40 AM
> 主題: Re: [ccp4bb] Mysterious Crystals?
> Fish and wash some crystals then run them on a
> SDS-gel, then you will know for sure if it's protein
> or not.
>
>
>
> J僡gen
>
> On Apr 18, 2010, at 10:46 PM, tat cheung cheng
> wrote:
>
> Hi all,
>
> I have got some crystals, the purified protein was
> in Tris buffer with 300mM NaCl for crystallization.
> they grew in light weight PEG, PEG400 or monomethyl
> ethyl PEG500, they were needle shaped, could be long
> (~0.2mm) but very thin all the time and sometimes
> grew into sea-urchin like needle cluster.
> What interesting is, when i gridded crystallization
> conditions against pH or PEG amount, the crystals
> sizes and shapes varied, and the crystals were
> fragile so i believed they were protein crystals in
> nature. But upon X-ray diffraction, they gave no
> reflection at all, not even a faint spot.
> I wonder, beside silly mistakes like misalignment of
> the crystal to the beam, not enough exposure time,
> what could be the reason for this mysterious
> crystals? Are they protein or PEG or what?
> Thanks very much.
>
> Tc
>
>
>
> -
>
> J僡gen Bosch
>
> Johns Hopkins Bloomberg School of Public Health
> Department of Biochemistry & Molecular Biology
> Johns Hopkins Malaria Research Institute
> 615 North Wolfe Street , W8708
> Baltimore , MD 21205
> Phone: +1-410-614-4742
> Lab: +1-410-614-4894
> Fax: +1-410-955-3655
> http://web.mac.com/bosch_lab/
>
>
>
>
>
>
Phoebe A. Rice
Assoc. Prof., Dept. of Biochemistry & Molecular Biology
The University of Chicago
phone 773 834 1723
http://bmb.bsd.uchicago.edu/Faculty_and_Research/01_Faculty/01_Faculty_Alphabetically.php?faculty_id=123
RNA is really nifty
DNA is over fifty
We have put them
both in one book
Please do take a
really good look
http://www.rsc.org/shop/books/2008/9780854042722.asp
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