Re: [ccp4bb] Do you have this type of diffraction pattern?

[James Phillips]

I agree with Roger Rowlett, try a room temp capillary mount.  Also ,what is
the magnification of the microscope/TV system you are using to center these
tiny crystals? Centering the loop is not enough.

James Phillips

On Fri, Dec 1, 2017 at 8:48 AM, Thomas, Leonard M.  wrote:

> Looking a bit closer are you sure the crystal is protein?  I see a couple
> of spots which could indicate a small molecule of some variety.
>
> Len
>
>
> On Nov 30, 2017, at 3:04 PM, Geny  wrote:
>
> ​
>
> Dear EveryOne,
> ​
> ​ I recently tried to collect the diffraction data, but unluckily, the
> diffraction patter is attached in this email. There is no any diffraction
> spots ​at all. It is my honor to ask experts worldwide why the crystal does
> this, and how to improve the quality of this kind of crystal. if you have
> any ideas, would you like to share?  Thank you so much and really
> appreciate it.
>
> Bests,
> Geny
>
>
> 
> 
>
>
> Leonard Thomas
> lmtho...@ou.edu
>
>
>
>

Re: [ccp4bb] Do you have this type of diffraction pattern?

[Thomas, Leonard M.]

Looking a bit closer are you sure the crystal is protein?  I see a couple of 
spots which could indicate a small molecule of some variety.

Len


On Nov 30, 2017, at 3:04 PM, Geny > 
wrote:

​

Dear EveryOne,
​
​ I recently tried to collect the diffraction data, but unluckily, the 
diffraction patter is attached in this email. There is no any diffraction spots 
​at all. It is my honor to ask experts worldwide why the crystal does this, and 
how to improve the quality of this kind of crystal. if you have any ideas, 
would you like to share?  Thank you so much and really appreciate it.

Bests,
Geny





Leonard Thomas
lmtho...@ou.edu

Re: [ccp4bb] Do you have this type of diffraction pattern?

[Ivan Shabalin]

Geny,

Unfortunately, it is a very common case. In our practice, we have 20-40% 
of protein crystals that show this kind of diffraction. We still call 
them crystals because they often look beautiful, with nice edges and 
planes. My understanding is that the protein molecules are not arranged 
orderly enough to show diffraction spots.


It is possible that the crystal was destroyed when the cryo protectant 
was added. You may try RT as suggested by Roger (which is the ultimate 
test), or just try other methods of cryoprotection and/or cryoprotectants.


For some ideas, i suggest looking into the paper "A review of techniques 
for maximizing diffraction from a protein crystal in stilla" by Janet 
Newman.


Shooting it a better X-ray source is unlikely to improve the picture 
significantly in my opinion. You may simply try increasing the radiation 
dose many folds to see if there are diffraction spots at all.


Good luck!

With best regards,
Ivan Shabalin, Ph.D.
Research Scientist,
Department of Molecular Physiology and Biological Physics,
University of Virginia,
1340 Jefferson Park Avenue, Pinn Hall,Room 4223,
Charlottesville, VA 22908

Re: [ccp4bb] Do you have this type of diffraction pattern?

[stenkamp]

Is it a crystal if there are no reflections?  Aren't Bragg reflections a 
necessary and sufficient condition for calling something a crystal?  Ron

On Thu, 30 Nov 2017, Geny wrote:



​Dear EveryOne,
​​I recently tried to collect the diffraction data, but unluckily, the 
diffraction patter is attached in this
email. There is no any diffraction spots ​at all. It is my honor to ask experts 
worldwide why the crystal does
this, and how to improve the quality of this kind of crystal. if you have any 
ideas, would you like to share? 
Thank you so much and really appreciate it.

Bests,
Geny


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