growing better crystals and thanks

Allan Sharp allan at mycroft.mmid.ualberta.ca
Mon Sep 30 20:41:22 EST 1996


jgluz at MAIL.MED.CORNELL.EDU wrote:
: Thanks to all the folks who took time to respond to my last inquiry 
: about mounting crystals.  Now another matter. I have two forms of my 
: crystal: one with cofactor and one with sustrate.  The former grows as a 
: thin rectangular plate.  I can see the edge but otherwise the crystals 
: are quite thin.  I was told thin crystals are not useful for x-ray 
: analysis.  Now I am trying to grow these crystls fatter but it's not 

You might test them anyways - sometimes flat plates will suprise you, although
your unlikely to get great data from them.

: working.  I've tried grids around the original condition, varying the pH 
: and salt and precipitant concentrations.  Any suggestions would be 
: greatly appreciated.  My other crystals grow as rectagular boxes that 
: are pointy at one end and hollow at the other.  What causes that 
: hollowness?  It looks strange.  Thanks again.--john        

I'm no expert, but I've heard it suggested that solute depletion can cause
hollows in crystals - i.e. the outer edge of the crystal is growing faster
than the inner edge because it's getting more contact with dissolved protein.
You can try adjusting your protein concentration, or try to slow down the
crystallisation process, by various means.

Allan M. Sharp 




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