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  From: Jeffrey C. Hansen <hansen@bioc02>
  To  : ccGeoff=Howlett%BioChem%UNIMELB@muwaye.unimelb.EDU.AU
  Date: Thu, 12 May 1994 11:09:53 +0000 (   )

Re: forthcoming van Holde/Weischet method explanation

> 1.  What is the Van Holde-Weischet method and what advantages does it offer?

Thanks for asking this question.  For those interested in the
answer, we ask your patience. Bo Demeler and I are working on a
comprehensive response, but we are both extremely busy at the moment.
It may take a few more days before it shows up on RASMB.

Briefly, the original paper is: van Holde & Weischet, Biopolymers (1978) 25,
1981-88. This is a G(s) method that uses a global fit to factor diffusion
out of a sedimentation velocity experiment.  The resulting integral
distribution of sedimentation coefficients can be used as a test for
homogeneity.  Perhaps more importantly, it allows one to characterize very
paucidisperse samples with confidence.  Finally, it also identifies
non-ideality.  In Jack's case, the upward sloping plateaus cause his samples
to appear non-ideal when this analysis method is used. Applications of
this method can be found in: Biochemistry (1989) 28, 9129-9136; JBC (1991)
266, 4276-82; Biochemistry (1992) 31, 7977-88; JBC (1993) 268, 5840-48;
Biochemistry (1994) 33, 2226-33; PNAS (1994) 91, 2339-43; JBC (1994) 269,
2447-51. Bo Demeler has programmed the van Holde-Weischet method (along with a
real-time data acquisition module and quite a bit more) into an
Origin-based data analysis package that allows one to edit and analyze by
this method a 20-30 scan velocity experiment in about 5 minutes. I hope
that this gives you at least a partial answer to question, and some insight
into the recent dialog concerning upward sloping plateaus.

- Jeff Hansen

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