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Sorry, I have come to this thread rather late. There seem to be two important differences between nanodrops (say 100 + 100 nl) and larger drops (e.g. 1 + 1 microlitres): 1. A greater proportion of the protein is lost in the nanodrops at the surface of the plastic and also at the air interface 2. The drops equilibrate faster in nanodrops Obviously the smaller drops have a greater surface-to-volume ratio. Data-mining of published high-throughput results suggests that increasing the salt can help when scaling up from nanodrops. Presumably this speeds up equilibration (it may also compensate for lost protein, but it doesn't seem to be necessary to increase PEG or other organics in hits with those materials). Heather Ringrose (Pfizer UK) also suggested that if you initially screen with 100 nl (reservoir) + 200 nl (protein) you will pick up conditions that scale up to 1 + 1 microlitres. This is discussed in more detail in the discussion group that we started up with Jon Hadden at Leeds University for discussions of general crystallization and automation. See the thread beginning http://clubs.wanadoo.co.uk/message/viewdiscussion.cfm?gid=2627826&messag eid=35 This discussion group also has many other comments about detergents, seeding, converting to microbatch etc. All new members welcome! Patrick -- [EMAIL PROTECTED] Douglas Instruments Ltd. DouglasHouse, EastGarston, Hungerford, Berkshire, RG177HD, UK Directors: Peter Baldock, Patrick Shaw Stewart, James Smith http://douglas.co.uk or http://www.douglasinstruments.com Tel: 44 (0) 148-864-9090 US toll-free 1-877-225-2034 > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Dirk > Kostrewa > Sent: 11 April 2006 08:31 > To: CCP4BB > Subject: Re: [ccp4bb]: Protein crystallization > > *** For details on how to be removed from this list visit the *** > *** CCP4 home page http://www.ccp4.ac.uk *** > > > Dear CCP4ers, > > Nat Echols wrote: > > ... > > I would definitely say that reproducing the crystals in a more standard > > format (i.e. 24-well sitting/hanging drop trays) doesn't always work as > > expected, but I've had this problem regardless of screen format. (I > > suspect as more and more people use robots this will continue to be an > > issue.) > ... > > yes, we have quite often problems now with upscaling an initial > crystallization condition from our robot 96 well plates with typically > 200-500 + 200-500 nl drop size to conventional 24 wells with 2-3 + 2-3 > ul drop size. It's clear, that the geometry is somewhat different, and > presumably the smaller drops mix faster, but currently, I have no idea > what the major obstacle for upscaling is. Does anybody of you have a > clue and, maybe, a solution or workaround? > > Best regards, > > Dirk. > > -- > > **************************************** > Dirk Kostrewa > Paul Scherrer Institut > Biomolecular Research, OFLC/110 > CH-5232 Villigen PSI, Switzerland > Phone: +41-56-310-4722 > Fax: +41-56-310-5288 > E-mail: [EMAIL PROTECTED] > http://sb.web.psi.ch > ****************************************
