Anhydrous trifluoroacetic acid pretreatment converts insoluble polyglutamine peptides to soluble monomers

Abstract

The data provided in this article are related to the research article entitled “Unaided trifluoroacetic acid pretreatment solubilizes polyglutamine (polyGln) peptides and retains their biophysical properties of aggregation” by Burra and Thakur (in press) [1]. This research article reports data from size exclusion chromatography (SEC), reversed phase-high performance liquid chromatography (RP-HPLC) and mass spectrometry (MS) assays. This data show that trifluoroacetic acid (TFA) has the ability to convert insoluble polyGln peptides to soluble monomers. The data also clarify the possibility of trifluoroacetylation modification caused due to TFA. We hope the data presented here will enhance the understanding of polyGln disaggregation and solubilization. For more insightful and useful discussions, see the research article published in Analytical Biochemistry: Methods in the Biological Sciences (Burra and Thakur, in press [1]).

Insights into the molecular mechanism behind solubilization of amyloidogenic polyglutamine‐containing peptides

“…Improper solubilization often leads to misinterpretation of the aggregation kinetics and its thermodynamics analysis . Solvent pretreatment is a common strategy to convert insoluble or sparingly soluble peptides and proteins into soluble monomers . For example, amyloidogenic peptides such as β‐amyloid, α‐synuclein, islet amyloid polypeptide, and polyGln containing peptides are treated with TFA and HFIP for improving solubility …”

“…The pure fraction of the peptide was collected in one glass vial (Borosil, 15 mL) based on its retention time and previously characterized mass spectrometry data (Supporting Information Figure S1b and Table S1). They were then freeze‐dried by using a lyophilizer and stored at −80 °C for future use …”

“…After incubation, the volatile solvents were removed using nitrogen gas, and their removal was ensured by further subjecting them to vacuum drying for 1 hour. The peptide stock solutions were generated by dissolving the dry peptide film in water‐TFA (pH 3.0) . Any insoluble material or aggregates were removed by subjecting the resultant peptide solution to ultracentrifugation at 350 300 g for 4 hours.…”

“…The PGQ 9 I peptide processed under TFA, HFIP, and TFA/HFIP conditions were adjusted to pH 7.4 by adding phosphate buffer saline (PBS) for SEC analysis . A 50 μL of this peptide was passed through GE healthcare Superdex peptide 10/300GL column connected to Biologic Duoflow chromatography system, Bio‐Rad.…”

Osmolytes modulate polyglutamine aggregation in a sequence dependent manner

“…Peptides were purified on a Zorbax reverse phase C3 column to single peak resolution, lyophilized, and stored at −80°C. Purified peptides were disaggregated prior to use as described, dissolved in acidic water set to pH 3 using trifluoroacetic acid (TFA) and subjected to high speed ultracentrifugation at approximately 350 000 g for 4 hours at 4°C. Top 80% of the supernatant of freshly disaggregated peptide was used to set up the aggregation reaction.…”