[RASMB] Overspeeding to establish equilibrium

[Walter Stafford]

At 19:03 +0100 6/25/02, Andrew Leech wrote:
>
>
>Is there a procedure, or rule of thumb, to decide how fast to
>run the AUC to minimise the time taken to reach equilibrium?
>
>I am thinking about unstable samples and how to avoid the long
>delays before reaching equilibrium.
>
>Andrew
>


Hi Andrew et RASMB,

I would like to bring your attention to a paper by Dennis Roark from 
ancient of days in which he gave an analysis of and little rule of 
thumb for computing the optimum overspeed time.

SEDIMENTATION EQUILIBRIUM TECHNIQUES - MULTIPLE SPEED ANALYSES AND AN 
OVERSPEED PROCEDURE.  ROARK DE, BIOPHYSICAL CHEMISTRY ,5 (1-2): 
185-196 1976


Also in that paper is a reference to work from David Teller's and 
Howard Schachman's labs describing extensive overspeeding simulations 
to find optimum overspeeding times. The one main caution I remember 
from that paper is that even a small amount of excessive overspeeding 
can drastically _increase_ the time to equilibrium. Choosing the 
right length of time for overspeeding was critical. I don't think 
they addressed the problems associated with reversible interaction or 
other concentration dependence.

I think this is the reference to that work:
ULTRACENTRIFUGE STUDIES WITH RAYLEIGH INTERFERENCE OPTICS .3. 
COMPUTATIONAL METHODS APPLIED TO HIGH-SPEED SEDIMENTATION EQUILIBRIUM 
EXPERIMENTS. TELLER DC, HORBETT TA, RICHARDS EG, SCHACHMA.HK,  ANNALS 
OF THE NEW YORK ACADEMY OF SCIENCES, 164 (A1): 66-& 1969
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Walter F. Stafford III, Ph.D.
Senior Scientist
Analytical Ultracentrifugation Research Laboratory
Boston Biomedical Research Institute
64 Grove Street
Watertown, MA  02472-2829
and
Associate in Neurology
Massachusetts General Hospital
Harvard Medical School
Boston MA 02115

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