[RASMB] Peptide sedimentation

[Lake Paul]

Marina,
First I would make sure you have at least 50 to 150 mM NaCl in your
buffer. I would also spin at 60,000 rpm if possible. If you can't then
do it at 50, 000 rpm for a longer time. The wavelength is dependent on
whether you have W, F or Y in your peptides. If you do then you can
use 280 nm. If you don't then 220-230 nm will be your best option. The
only catch is that you have to make sure your buffer does not absorb
in that wavelength range. Fortunately, the masters of the AUC did
these experiments for us and there is a list of acceptable buffers you
can use. Phosphate is a good one at that wavelength. I would also
search the archives of RASMB. I would treat it like a peptide like a
protein in terms of concentration. 0.1 to 1.3 OD range or the range in
which you see aggregation.
This should get you started.
Lake

On Tue, Jul 9, 2013 at 5:51 AM, Fasolini, Marina [Nervianoms]
<Marina.Fasolini at nervianoms.com> wrote:
> Dear All
> I need to follow the aggregation of some peptides of about 4 KDa . I would
> like to estimate the dimension of these aggregates.
> Since my experience is mostly in protein sedimentation, I was wondering if
> you have some tips for me. Which wavelength do you use for absorbance optic?
> Which is the best concentration to run?
> At which speed do you suggest me to run the experiment?
> Any help will be appreciated.
> Thanks in advance
> Marina
>
>
>
> MARINA FASOLINI
> Structural Chemistry
>
> Nerviano Medical Sciences http://www.nervianoms.com
> Viale Pasteur 10
> 20014 Nerviano - Milano
> marina.fasolini at nervianoms.com
> Tel. +390331581462
> Fax. +390331581360
>
>
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-- 
Lake Paul, PhD

Biophysical Analysis Lab
Purdue Proteomics Facility

Bindley Bioscience Center
Purdue University
1203 West State Street,
West Lafayette, Indiana, 47095
765.494.4960