Hi Frank,
Do not forget that membrane protein crystals are often fragile and
difficult to manipulate.
Finding good cryo condition can be difficult and small temperature
variation can destroy crystals
within minutes, this makes room temperature diffraction tests not always
obvious. The time of harvest may also be critical. In addition to the
previous suggestions, it is often usefull to check if there is a large
amount of lipids in the sample. This can often easily be done by thin
layer chromatography.
HTH
Daniel
Le 23/10/2013 18:22, crystalboy a écrit :
> Hi CCP4BB Forks,
>
> In recently I got a membrane protein crystal in the quite normal
> membrane protein crystallization conditions as other persons reported,
> like PEG400 16-19%, pH 6.0-7.5, with 50 mM MgCl2 (in my case) by using
> sitting drop method. These crystals are around 50-100 uM. They look
> like trapezoid crystal. My problem is all of my crystals have not
> diffraction in home source X-ray and just poor diffraction at
> Synchrotron (lower than 20 A). My crystals like to appear on the
> surface of the drop. Look like my crystals are quite light. I had
> tried to use a needle to touch them. Unlike other protein crystal, my
> crystal looks like quite "soft". When I touch it, it didn't crack, but
> was bend or mashed. I had tried to do additive screen and detergent
> screen. It seems they are not useful.
>
> Do anyone have good ideas to optimization these crystals? Thanks for
> your suggestions.
>
> Frank
