Dear Roger, Since you already have initial crystallisation conditions and crystals you could try dialysis buttons to further reduce the glycerol content (and hence get bigger crystals). They are available e.g. from Hampton, the minimum volume is 5 mul and I find they require a little skill to set up.
Good luck, Tim On Wed, Aug 25, 2010 at 10:19:13AM -0400, Roger Rowlett wrote: > <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> > <html> > <head> > > <meta http-equiv="content-type" content="text/html; charset=ISO-8859-1"> > </head> > <body bgcolor="#ffffff" text="#000000"> > <font face="Verdana">Does anyone have practical experience > crystallizing low solubility proteins from solutions containing > significant (10-20%) glycerol? We can get small crystals by mixing > 4:1 ratios of protein to well solution, but the drops do not > concentrate back to the well solution volume as anticipated, even > if the well solution is brought to 10-20% glycerol as well to > balance osmolarity. Concentration of the protein further to reduce > the protein:well solution ratio may not be practical (it crashes > out) even in 20% glycerol. Unfortunately, glycerol seems to be > required to maintain protein solubility, so that may not be > practical to remove either.<br> > <br> > One thought is to add additional osmolyte to the well solution to > draw down the drop volume once small crystals form, a kind of a > "macro-seeding" approach, but I am not aware of a systematic way > of doing this. Anyway, I am almost certain I am trying to > re-invent the wheel,as someone has probably done something > similar. Any suggestions would be appreciated.<br> > <br> > Cheers,<br> > </font><br> > <div class="moz-signature">-- <br> > <font face="Verdana"> > <hr> > Roger S. Rowlett<br> > Professor<br> > Department of Chemistry<br> > Colgate University<br> > 13 Oak Drive<br> > Hamilton, NY 13346<br> > <br> > tel: (315)-228-7245<br> > ofc: (315)-228-7395<br> > fax: (315)-228-7935<br> > email: <a class="moz-txt-link-abbreviated" > href="mailto:rrowl...@colgate.edu";>rrowl...@colgate.edu</a><br> > </font> > </div> > </body> > </html> -- -- Tim Gruene Institut fuer anorganische Chemie Tammannstr. 4 D-37077 Goettingen GPG Key ID = A46BEE1A
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