[RASMB] glycerol gradient

[Tom Laue]

Hi-
The gradient in your data is from both the salt (s ~ 0.25) and glycerol 
(s~0.2). Tris is neutrally buoyant (or nearly so). Years back we did a 
series of equilibrium experiments to see if the high viscosity of 
glycerol could be traced to associative interactions (my recollection is 
that association was not strong enough to overcome repulsive interactions).
Allen Minton may have some data on this...
Best wishes,
Tom

Piszczek, Grzegorz (NIH/NHLBI) [E] wrote:
> Jack,
>
> I found some old data for buffer containing 10% glycerol, 50mM Tris and 0.1M KCl run against water at 45k - see the attached file.
>
> Hope this helps,
>   Greg
>
>
> -----Original Message-----
> From: rasmb-bounces at rasmb.bbri.org [mailto:rasmb-bounces at rasmb.bbri.org] On Behalf Of Jack Kornblatt
> Sent: Thursday, May 07, 2009 4:57 PM
> To: rasmb at server1.bbri.org
> Subject: [RASMB] glycerol and the formation of gradients
>
> Dear All
> Back in 2003 Borries Demeler made the following suggestion to a question:
>
> "Marcello,
>
> that's quite a bit of glycerol. Depending on the speed, I'd be concerned about building up a glycerol gradient inside your velocity experiment which would also give a gradient of density and viscosity, causing the sample to slow down towards the bottom of the cell (it hits a glycerol cushion?). Just another variable to think about. One thing you might want to do to verify this is to run glycerol against water to see if the effect is large enough ito worry about at the speed you are running it. 
> Should be possible with and XLI.
>
> Regards, -Borries"
>
> I have searched the archives and have done a day's search of the literature but I've not found any sign that people have taken Borries' 
> suggestion to heart. Has anyone out there measured the sedimentation of glycerol? We have an XL-I and plan to do the experiment tomorrow but it would be very nice to have something to compare the results to. This presumes, of course, that there are results. If there are, I'll let you know.
>
> On reflection, Jim Cole, might have the data. His 1996 paper on glycerol effects still impresses one.
>
> best to all
> jack (kornblatt)
>
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-- 
Department of Biochemistry and Molecular Biology
University of New Hampshire
Durham, NH 03824-3544
Phone: 603-862-2459
FAX:   603-862-0031
E-mail: Tom.Laue at unh.edu
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