-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Dear Chang,
What makes you think spots from salt crystals should not be as large? You have got an ordinary small molecule crystal (or probably a cluster of them) in the beam, with a unit cell somewhat bigger than that of ice judging by the extra real ice rings you've got. Hydrolysis of ATP and Mg2+ present - it's probably (Mg)3(PO4)2- it is very unsoluble http://en.wikipedia.org/wiki/Solubility_table. Best, Tim On 10/12/2012 09:29 AM, Chang Qing wrote: > Hi, Thanks for answering my question. I think I'd better provide > more informations. These four images were taken from one crystals. > The distance of image1-2 is 250mm, and image3-4 is 100mm. I checked > more than 10 crystals and results were similar. The spots look very > large. The lowest resolution is about 6A. As my protein can > hydrolyze ATP, so protein buffer with 5mM of ATP. There is 0.2M of > MgCl2 in precipitant buffer with PH7.0. 0.06M of CsCl can improve > quality of crystals. I also setup control, in which target protein > was not added, and could get nothing in it. I don't think it is a > protein crystal. But salt spot should not be so large. And the > rings are not just ice-ring. As I got crystal first in hampton > crystal screen kit with MgCl2, TrisHCl and PEG4,000, there are only > rings in images from 5-6A to about 3A. > > 2012/10/12 THOMPSON Andrew > <andrew.thomp...@synchrotron-soleil.fr>: >> Hi Chang No mention of the resolution limit / oscillation range >> (I think I can see an ice ring, so I would guess 2.5 A?), but it >> looks like salt to me, with some weaker satellite peaks that may >> be something weird like an incommensurate phase. Did you try to >> index? Cheers Andy ________________________________________ De : >> CCP4 bulletin board [CCP4BB@JISCMAIL.AC.UK] de la part de Chang >> Qing [robie0...@gmail.com] Date d'envoi : vendredi 12 octobre >> 2012 08:11 À : CCP4BB@JISCMAIL.AC.UK Objet : [ccp4bb] Strange >> diffraction image >> >> Hi, everyone: >> >> I just got some strange diffraction images from crystals with >> triangular pyramid shape. I think this should not be protein >> diffraction. I never saw so strange images like this. Does anyone >> know what it is? Is it a kind of salt diffraction? Thank you very >> much >> >> Chang > - -- - -- Dr Tim Gruene Institut fuer anorganische Chemie Tammannstr. 4 D-37077 Goettingen GPG Key ID = A46BEE1A -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iD8DBQFQeAheUxlJ7aRr7hoRAibDAJ9yAfiSwNmh8R4tGwUIwFEZno2qWACfStCM y+xKb+FGGglmv8lTL9Ej8ZQ= =ub/P -----END PGP SIGNATURE-----
