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RE: [ccp4bb]: Vibration (was re:Dehydration)

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Many years ago at Imperial College we did a fairly systematic experiment on
vibration using lysozyme (hanging drops).
We placed one tray in the basement on a very solid base, one tray was placed
in an incubator, known to vibrate a little and which was often used
(frequent door opening and closing), and the third tray was placed on a
rather strongly vibrating plate hanging from a stand. The vibrations were
produced by a small motor with an acentric piece of metal attached to it.
The trays were examined at regular intervals. Crystals grew in all of them.
The basement tray gave fewer but bigger crystals, but this may have been a
small temperature effect - temperature was not controlled very well.
Crystals from all trays were nice, they diffracted to the same resolution,
with virtually identical Wilson distribution. After this experiment we
stopped worrying about vibration.

Tadeusz Skarzynski
Protein Structure Group

> -----Original Message-----
> From:	Richard Gillilan [SMTP:reg8@cornell.edu]
> Sent:	Tuesday, June 05, 2001 2:45 PM
> To:	ccp4bb@dl.ac.uk
> Subject:	[ccp4bb]: Vibration (was re:Dehydration)
> ***  For details on how to be removed from this list visit the  ***
> ***          CCP4 home page http://www.ccp4.ac.uk         ***
> Hemant Yennawar wrote:
> > Hello Ccp4bb,
> > One of the magic bullets (as we all know, each protein needs a different
> > one) for improving
> > crystal quality was floatation of the crystallization trays.  Floating
> the
> > trays isolate
> > them from the vibrations.  We used a sheet of styrofoam  as a floating
> > platform for the tray.
> > Further, to avoid evaporation of the water under the styrofoam sheet,  a
> > dessicator with lid was used.  Hope some other proteins also yield to
> this
> > treatment.
> >
> Recently, I set out two identical trays of lysozyme (hanging drops).
> One I put on the usual shelf, the other I put on top of our 6-processor
> Linux cluster. Both trays were put inside styrofoam coolers at room
> temperature with thermometers ... there were no significant temperature
> differences between the two.
> After 3 days, the tray on the shelf yielded the usual lovely crystals.
> Much to my surprise, the tray on the Linux cluster had almost NO
> crystals at all ... even after more than a week.  After a couple weeks,
> I removed it to a regular shelf and crystals formed over night.
> Conventional wisdom, would be that vibration increases nucleation ....
> but this would seem to demonstrate the opposite.  The cluster really does
> not
> vibrate much ... it is barely perceptable to the touch
> ..... so .... It may not be a good idea to have a computer on the same
> bench as your crystal trays.
> Floatation sounds like a great idea. I had recently borrowed a motion
> isolation table that uses gas floatation, but have not yet started using
> it.
> Has anyone else done systematic vibration experiments?
> I only have a couple literature references.
> Richard Gillilan
> Cornell University