There was an abstract/poster at Neuroscience 2014 (put on by SfN) which showed data using MALDI-TOF to characterize: 1) the monomerization of the amyloid beta peptide by each of the most common solvents (i.e. ammonium hydroxide NH4OH, HFIP, TFA), as well as 2) the relative quantities of oligomeric species formed in each subsequent buffer (i.e. F12, PBS, and water).

The results suggested that NH4OH provided a more complete monomerization of the peptide than any other solvent (monomer:dimer ratio = 30) with HFIP coming in slightly lower (monomer:dimer=8).  When I asked the author, she suggested that with HFIP, a second lyophilization and re-suspension step brought the monomerization ratio much closer to that of NH4OH, though she expressed concern for using pure, non-contaminated HFIP to reduce the formation of non-beta-sheet species of amyloid beta.

For oligomerization, the peptide monomers were suspended in DMSO and then diluted in each of the buffers (F12, PBS, H2O). Her results suggested greater quantities (about 2x) of each low-molecular weight oligomers formed in H2O than in either F12 or PBS, and that the quantity of each species (monomer, dimer, trimer, tetramer) was approximately equal between the F12 and PBS. There was no mention of when or where these results would be published.

You can view the abstract using SfN's Neuroscience meeting planner here:

http://www.abstractsonline.com/Plan/ViewAbstract.aspx?sKey=2db62a76-5aad-42e0-9c73-b4ee1c336d80&cKey=f69eacf2-ee12-4bec-9b9e-127881e07b12&mKey=%7b54C85D94-6D69-4B09-AFAA-502C0E680CA7%7d

Program#/Poster#: 407.02/F9 Monday, Nov 17, 2014, 1:00 PM - 5:00 PM

Characterization of amyloid beta oligomeric composition using matrix assisted laser desorption ionization mass spectrometry

*J. S. WANG1, K. JURCIC2, S. WHITEHEAD3, K. K. C. YEUNG1;

1Chem., 2Biochem., 3Anat. and Cell Biol., Western Univ., London, ON, Canada

I hope that helps,

-Travis

Dear Tanya,

Prof Dobson's group has several papers on interplay of solvents on amyloid fibril formation. A few examples which might help you are:

http://www.ncbi.nlm.nih.gov/pubmed/11714922

http://www.ncbi.nlm.nih.gov/pubmed/10097081

http://www.ncbi.nlm.nih.gov/pubmed/10747012

Best,

Jogender

Good day,

I don't know of any studies looking at the aggregrates formed by each of the amyloid beta salts, but this one compares amyloid beta 1-42 peptide dissolved in NaOH and HFIP:

http://www.ncbi.nlm.nih.gov/pubmed/23678397

and this chapter from Methods in Molecular Biology discusses the various solvent preparations:

http://www.ncbi.nlm.nih.gov/pubmed/?term=20967583

Lastly, Table 1 of this Nature Protocols paper lays out a detailed method for reliably obtaining the conformation of amyloid beta aggregate(s) of your choice:

http://www.nature.com/nprot/journal/v5/n6/full/nprot.2010.72.html

Good luck!

-Travis

pH has significant effect of Abeta amyloid development. At acidic conditions, proto- and mature fibrils develop within a relatively short time span. While, DMSO, acting as micelles, can promote the formation of oligomers instead of fibrillar structures.and seed amyloidogenic species. 

Thank you all for your help! I'm a cell biologist/immunologist stumbling into biochemistry and really appreciate the insights and suggested reading!

I dont know if I understoofd your question correctly! From a food scientist's point of view, in order to form fibrils resulting in clear gels, the random aggregation pathways need to be inhibited. Any factors which decrease the electrostatic repulsion between the building blocks (salts like NaCl or CaCl2) will increase self-assembly. However they would also influence morphology of fibrils. Slightly off discipline! But I hope it may provide some insights into the mechanisms.

There was an abstract/poster at Neuroscience 2014 (put on by SfN) which showed data using MALDI-TOF to characterize: 1) the monomerization of the amyloid beta peptide by each of the most common solvents (i.e. ammonium hydroxide NH4OH, HFIP, TFA), as well as 2) the relative quantities of oligomeric species formed in each subsequent buffer (i.e. F12, PBS, and water).

The results suggested that NH4OH provided a more complete monomerization of the peptide than any other solvent (monomer:dimer ratio = 30) with HFIP coming in slightly lower (monomer:dimer=8).  When I asked the author, she suggested that with HFIP, a second lyophilization and re-suspension step brought the monomerization ratio much closer to that of NH4OH, though she expressed concern for using pure, non-contaminated HFIP to reduce the formation of non-beta-sheet species of amyloid beta.

For oligomerization, the peptide monomers were suspended in DMSO and then diluted in each of the buffers (F12, PBS, H2O). Her results suggested greater quantities (about 2x) of each low-molecular weight oligomers formed in H2O than in either F12 or PBS, and that the quantity of each species (monomer, dimer, trimer, tetramer) was approximately equal between the F12 and PBS. There was no mention of when or where these results would be published.

You can view the abstract using SfN's Neuroscience meeting planner here:

http://www.abstractsonline.com/Plan/ViewAbstract.aspx?sKey=2db62a76-5aad-42e0-9c73-b4ee1c336d80&cKey=f69eacf2-ee12-4bec-9b9e-127881e07b12&mKey=%7b54C85D94-6D69-4B09-AFAA-502C0E680CA7%7d

Program#/Poster#: 407.02/F9 Monday, Nov 17, 2014, 1:00 PM - 5:00 PM

Characterization of amyloid beta oligomeric composition using matrix assisted laser desorption ionization mass spectrometry

*J. S. WANG1, K. JURCIC2, S. WHITEHEAD3, K. K. C. YEUNG1;

1Chem., 2Biochem., 3Anat. and Cell Biol., Western Univ., London, ON, Canada

I hope that helps,

-Travis