Hi, I beg to differ. Evaporation rates change dramatically between a
drop lying on a flat surface open to air flow; a drop lying in a
depression; and a drop lying in a depression with some reservoir
solution next to it. We're talking seconds to minutes.
So especially when using robotics to set up lots of drops, you might
find increased precipitation (or nucleation?) events in hanging drops --
but also less repeatable experiments.
As for visualisation: a proper drop shape (e.g. as used in the SwissCi
MRC or 3-drop plates) can make a big difference; certainly those are
superior to average hanging drop, I argue. (Whatever "superior" means.)
phx
Bostjan Kobe wrote:
There is really not much difference in terms of setup between hanging and
sitting drop, especially if the drops are set up on tape. Visualization is
also usually easier with hanging drops.
Bostjan
On 1/05/09 1:37 AM, "Poul Nissen" <p...@mb.au.dk> wrote:
We often find results to be very different between hanging and sitting
drops (equilibration kinetics for one may be the explanation). Then
there's the good thing of hanging drops that crystals rarely stick to
the surface of the support facilitating the mounting procedure, in
particular for fragile crystals.
All in all we much prefer hanging drops for our membrane proteins -
the bottle neck is not in the extra few minutes for set-up, but in the
months it takes to produce the protein.
Poul
On 30/04/2009, at 16.45, Jacob Keller wrote:
I have noticed that a significant majority of crystallizations are
done in hanging- rather than sitting-drop configuration, and
considering the significant extra labor involved in hanging drops,
can only understand this preference as a historical bias. I
understand that sometimes one technique works and not the other, but
all things being equal, why is hanging drop still "hanging around?"
Any insights appreciated...
Jacob Keller
*******************************************
Jacob Pearson Keller
Northwestern University
Medical Scientist Training Program
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lab: 847.491.2438
cel: 773.608.9185
email: j-kell...@northwestern.edu
*******************************************
---
Bostjan Kobe
ARC Federation Fellow
Professor of Structural Biology
School of Chemistry and Molecular Biosciences
and Institute for Molecular Bioscience
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University of Queensland
Brisbane, Queensland 4072
Australia
Phone: +61 7 3365 2132
Fax: +61 7 3365 4699
E-mail: b.k...@uq.edu.au
URL: http://profiles.bacs.uq.edu.au/Bostjan.Kobe.html
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