Dear Zhiyi,
Ezra is exactly right, of course. The Oxford Diffraction PX Scanner system can assess the diffraction qualities of (putative) protein crystals in situ - in the crystallisation plate. So, directly, you would discover if your 'big and beautiful' crystals actually diffract well... in their mother liquor under ambient conditions and before the addition of any cryo-protect. Do you have a friend or neighbour with a PX Scanner ? If not, please feel most welcome to contact Oxford Diffraction: we would be pleased to assist if at all possible. Good Luck and Best Wishes, Marcus Winter. www.oxford-diffraction.com -----Original Message----- From: CCP4 bulletin board [mailto:ccp...@jiscmail.ac.uk] On Behalf Of Ezra Peisach Sent: 26 January 2010 16:01 To: CCP4BB@JISCMAIL.AC.UK Subject: Re: [ccp4bb] Crystal rescue First you need to establish if it is your cryo conditions or the crystals. Depending where you are - they might have the equipment to do a wet mount - without freezing. Yes the crystal will not last - but then you know if the problem is in the crystal. If it is - you need better crystals. If it is the cryo - you need to work on that. Tacsimate is mixture of alot of different compounds - but the smears are too close together to be a small salt crystal on top... Good luck, Ezra On 1/26/2010 10:42 AM, Zhiyi Wei wrote: > Dear all, > > I got a problem with my crystals. I have two total different proteins > that both can be crystallized in the condition with PEG3350 and Tacsimate > (although the concentrations are different) with different shapes. The > crystals look big and beautiful. However, when I test them in synchrotron, > both of these two types of crystals showed poor diffractions. As showed in > the attached diffraction image, the diffraction is up to ~4 A but smear in > one direction while<8 A in the other direction. The interesting thing is > that the diffraction pattern is similar for all crystals (from two different > proteins) that I tested without exception although they belong to different > space groups. So, I wonder whether these kind of pattern is caused by > Tacsimate (I don't know what it is) and how to rescue these crystals. Any > suggestions or comments? > > Thanks a lot! > > Best, > Zhiyi >
