[RASMB] Oligomerization of small peptides (20-30 aa)...

[Lake N. Paul, PhD]

Hans-Joachim,
Using ESI to show oligiomerization states can be extremely tricky since you are
going to see a series of multiply charged ions. It will take some detailed
deconvolution to sort out the peptides (Waters' Protein Lynx program can do it).
Also the strength of the interaction will be tested, since you are going to be
under acidic conditions (i.e 0.1% TFA/FA). There is a new matrix developed by
Daniel Armstrong (University of Texas) called Ionic Liquid Matrix (ILM) that is
used under MADLI conditions. I have been using this matrix to complement my AUC
experiments. The principle behind these ionic liquid matrixes is to preserve the
non-covalent complexes by maintaining the pH around 7 or greater. So far I have
been able to detect GFP tetramers (~120 kDa)relatively easy in the gas phase and
also in my AUC experiments. These experiments take some tweaking before you can
detect the higher order oligiomers but email me and I will will start you on
your way.
Best,
Lake

-- 
Lake N. Paul, PhD
Biophysics Research Specialist
Discovery Park - Bindley Biosciences Center
Purdue University
1201 West State Street
West Lafayette, Indiana, 47905
lpaul at purdue.edu
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"The great tragedy of Science - the slaying of a beautiful hypothesis by an ugly
fact." -- Thomas H. Huxley
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Quoting "Schoenfeld, Hans-J." <hans-j.schoenfeld at roche.com>:

> Dear RASMB colleagues,
> the methods of choice to characterize peptide oligomerization in solution so
> far in my view were AUC in equilibrium mode or static light scattering
> methods...
> Recently, I heart about attempts to investigate peptide oligomerization as
> function of pH, buffer composition, etc. by electron spray mass spectroscopy.
> Are there opinions around about how MS methods in doing that compare to the
> more classical methods as mentioned above. I can hardly believe how MS could
> work without significantly influencing weak interactions or change
> equilibria...
> Thanks for any comment on that topic.
> Best regards,
> Hans-Joachim.
> Ps: also grateful for any literature of review references on this topic...
> 
> ============================================
> Dr. Hans-Joachim Schönfeld
> F. Hoffmann-La Roche Inc.
> Preclinical research, B93/5.44
> CH-4070 Basel
> Switzerland
> 
> Tel. (+41) 61 688 28 95
> Fax. (+41) 61 688 90 60
> mailto:hans-j.schoenfeld at roche.com
> 
>