Hello Yu,

As every one knows, this is major crystallization problem for large
difficult protein targets, specially  proteins with large moving loops
and/or domains may be responsible for this unique crystals/diffraction
pattern. If you think your protein has large moving loop/domain in
presence/absence of ligands, adding specific substrate/additives or
removing loop/domain through site directed mutagenesis or making different
construct of your protein domains (if you are interested in only unique
protein structure)  may be another option to obtained better crystals
depends on the method, which you are going to solve the crystal structure.

This is another way of obtaining better crystals in addition to above
mentioned useful comments.

Wish you good luck for better crystals,
Satya



On Wed, Feb 14, 2018 at 12:33 PM, Kevin Jin <kevin...@gmail.com> wrote:

> Hi Yu,
>
> I did not see your images before I sent my previous email. I had a same
> case like this long time ago. However, the diffraction image was much worse
> than your. After I modified the condition, I got a single crystal with
> clear edges and reasonable resolution (not diffraction to 2.7 Ang). I have
> no idea which kind of protein you are working on. Membrane protein?
>
> Here is my understanding for your laughing,
>
> 1. According to your diffraction image, those spots (with red circles,
> image attached) may not be diffractions from ice and organic salt. Did you
> use your mouse to check the distance between these spot manually? It may
> give you clues for size of the unit cell, if you can not index it. It will
> be helpful If there was another image with 90 degree offset.
>
> 2. For your first image, folk discussed before here. It is a phase
> separation. In this case, you need to change the ratio between the
> hydrophobic portion (may be a little bit high here?) and hydrophilic
> portion. For instance,
> (1) if you used 20% PEG8K, then you may try 20% PGE 6K or 20% PGE 3300.
> (2) Sometimes, the combination of 2-5% 2-propanol with < 5mM ZnCl2 could
> also give some surprising results.
> (3). Change your salt concentration, and try different anions for
> comparison, Cl vs SO4.
>
> The whole idea above is to fine shuffle the surface charge for better
> packing.
>
> 3. Change your buffer salt with the same pH.
> 4.  You may try some surface detergent.
> 5. Decrease the concentration of your protein sample.
>
> However, each protein has its unique characteristics for crystallization.
>
>  Best Regards,
>
> Kevin
>
> On Tue, Feb 13, 2018 at 1:03 PM, Yu Qiu <yu....@sanofi.com> wrote:
>
>> As asked by a few people, here are the images of crystals and diffraction.
>>
>>
>>
>> Thanks,
>>
>> Yu
>>
>>
>>
>> *From:* CCP4 bulletin board [mailto:CCP4BB@JISCMAIL.AC.UK] *On Behalf Of
>> *Keller, Jacob
>> *Sent:* Tuesday, February 13, 2018 4:00 PM
>> *To:* CCP4BB@JISCMAIL.AC.UK
>> *Subject:* [EXTERNAL] Re: [ccp4bb] protein quasicrystals?
>>
>>
>>
>> I also would love to see an imageā€¦.
>>
>>
>>
>> JPK
>>
>>
>>
>> +++++++++++++++++++++++++++++++++++++++++++++++++
>>
>> Jacob Pearson Keller
>>
>> Research Scientist / Looger Lab
>>
>> HHMI Janelia Research Campus
>>
>> 19700 Helix Dr, Ashburn, VA 20147
>> <https://maps.google.com/?q=19700+Helix+Dr,+Ashburn,+VA+20147&entry=gmail&source=g>
>>
>> Desk: (571)209-4000 x3159 <(571)%20209-4000>
>>
>> Cell: (301)592-7004 <(301)%20592-7004>
>>
>> +++++++++++++++++++++++++++++++++++++++++++++++++
>>
>>
>>
>> The content of this email is confidential and intended for the recipient
>> specified in message only. It is strictly forbidden to share any part of
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>> If you received this message by mistake, please reply to this message and
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>>
>>
>>
>> *From:* CCP4 bulletin board [mailto:CCP4BB@JISCMAIL.AC.UK
>> <CCP4BB@JISCMAIL.AC.UK>] *On Behalf Of *James Phillips
>> *Sent:* Tuesday, February 13, 2018 3:03 PM
>> *To:* CCP4BB@JISCMAIL.AC.UK
>> *Subject:* Re: [ccp4bb] protein quasicrystals?
>>
>>
>>
>> There are programs which are good at indexing patterns from multiply
>> twinned crystals. Bruker AXS has one, to my knowledge. There may be other
>> sources. I suggest you try that first before you invoke a quasicrystal
>> explanation.
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> James Phillips
>>
>>
>>
>> On Tue, Feb 13, 2018 at 12:07 PM, Takanori Nakane <
>> tnak...@mrc-lmb.cam.ac.uk> wrote:
>>
>> Hi,
>>
>> "dials.reciprocal_space_viewer" is very useful to identify multiple
>> lattices.
>> For quasicrystal and modulated crystals, "dials.rs_mapper" is also very
>> useful.
>>
>> Best regards,
>>
>> Takanori Nakane
>>
>>
>> > Have you tried microseeding of these sphere crystals? It may help to get
>> > better crystals.
>> >
>> >
>> > Burak
>> >
>> > ________________________________
>> > From: CCP4 bulletin board <CCP4BB@JISCMAIL.AC.UK> on behalf of Yu Qiu
>> > <yu....@sanofi.com>
>> > Sent: 13 February 2018 15:09:43
>> > To: CCP4BB@JISCMAIL.AC.UK
>> > Subject: [ccp4bb] protein quasicrystals?
>> >
>> >
>> > Hi,
>> >
>> >
>> >
>> > I have been trying to crystallize a protein complex and keep getting
>> > sphere shape crystals. The diffraction is around 3 angstrom, but looks
>> > like multiple lattices. I am wondering if it could be a quasi crystal?
>> Is
>> > there anyone has such experience?
>> >
>> >
>> >
>> > Thanks,
>> >
>> > Yu
>> >
>>
>>
>>
>
>
>
> --
> Kevin Jin
>
> Sharing knowledge each other is always very joyful......
>
> Website: http://www.jinkai.org/
>
>

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