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

[Peter Edward Prevelige Jr]

This is something we do a bit of. To look at complexes is non-trivial  
but doable.  You actually spray at neutral pH so you don't denature  
the protein. As a result the charge state is low and the m/z is high,  
think ToF instruments. Increasing pressure in the first stage is  
required to cool/focus the ions.  Good reviews by Carol Robinson and  
group.

The thought and limited data are that electrostatic interactions are  
strengthened and hydrophobic are weakened. I don't know of any  
rigorous comparisons with solution measurements.

We have found it useful for some problems but won't be reading in our  
AU or LS instrumentation.

Peter Prevelige
University of Alabama Birmingham

Sent from my iPhone

On Feb 10, 2010, at 7:53 AM, "Lake N. Paul, PhD" <lpaul at purdue.edu>  
wrote:

> 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
> --- 
> --- 
> --- 
> --- 
> --------------------------------------------------------------------
> "The great tragedy of Science - the slaying of a beautiful  
> hypothesis by an ugly
> fact." -- Thomas H. Huxley
> --- 
> --- 
> --- 
> --- 
> --------------------------------------------------------------------
>
>
> 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
>>
>>
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