Dear Diana, I have adopted this method, and for the reasons your users suggest, here at Manchester and do not observe any clogging of the nano probe due to evaporation. The computer interface does complain that there is no protein solution aspirated after the initial run but this is not a 'fatal' error and the modified protocol runs. On the other hand, the transfer losses on a simple protocol will be small (you could easily and quickly check this by careful weighing), in the order of a few microlitre and the user has to remember to correctly modify the protocol after the initial run and at the end of the run. Precious protein may be lost by mistakes here. My only other observation is that the nano purge is quite violent and may introduce bubbles or a foamy layer in the protein sample.
Regards, Pat Bryant Dr Pat Bryant Senior Experimental Officer Macromolecular Crystallography Core Facility Faculty of Life Sciences Michael Smith Building The University of Manchester Oxford Road Manchester M13 9PT, UK Phone: +44-161-275-5090/5658 Fax: +44-161-275-1505 email: [EMAIL PROTECTED] Intranet:http://www.intranet.ls,manchester.ac.uk/facilities/research/xraycrystallography Internet:http://www.ls.manchester.ac.uk/research/facilities/xray -----Original Message----- From: CCP4 bulletin board [mailto:[EMAIL PROTECTED] On Behalf Of Diana Tomchick Sent: 24 April 2008 17:31 To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] Question about Phoenix crystallization robot BACKGROUND: Recently we acquired an Art Robbins Phoenix crystallization robot. This instrument is in a shared environment, accessible to labs with projects that range from small, well-behaved soluble cytosolic proteins to large complexes and integral membrane proteins. Many of our users obtain only small quantities (a few hundred microliters) of purified proteins, and they are always looking for ways to maximize the number of crystallization screens they can set up with their samples. QUESTION: Several users have recently asked if they could use a protocol that allows them to aspirate enough protein into the Nanoneedle (the needle used for dispensing protein) to set up 3-5 or more different 96-condition screens. They feel this would minimize any sample waste and maximize their time. Our concern is that this might result in clogging of the Nanoneedle due to evaporation and subsequent precipitation of their protein, as the amount of time required for such a protocol would be greater than 10 minutes. Our local Art Robbins representative has agreed with us that this is not a recommended protocol. We are in a bit of a dilemma as we do not have enough experience with this robot to definitively say that the users should not follow this kind of protocol, but perhaps there is a better way to achieve their desired goal. Does anyone out there have any practical suggestions and experience that could help us accommodate such user requests? Thank you in advance, I'll post a summary of responses, Diana * * * * * * * * * * * * * * * * * * * * * * * * * * * * Diana R. Tomchick Associate Professor University of Texas Southwestern Medical Center Department of Biochemistry 5323 Harry Hines Blvd. Rm. ND10.214B Dallas, TX 75390-8816, U.S.A. Email: [EMAIL PROTECTED] 214-645-6383 (phone) 214-645-6353 (fax)
