Predictive model for capillary electrophoretic peptide mobility in 2,2,2-trifluoroethanol-water solution

Area of Science:

• Analytical Chemistry
• Physical Chemistry
• Biochemistry

Background:

• Accurate prediction of peptide physicochemical properties is crucial for separation science.
• Semiempirical models require validation for peptide size and charge under various conditions.
• Understanding peptide behavior in different solvent systems, like trifluoroethanol (TFE) mixtures, is important.

Purpose of the Study:

• To determine Stokes radii and acidic dissociation constants for peptides.
• To evaluate the reliability of semiempirical models for predicting peptide size and charge.
• To establish predictive equations for peptide mobility based on charge-to-size ratio.

Main Methods:

• Capillary electrophoresis (CE) was used to analyze 21 peptides (350–1850 Da).
• Measurements were conducted in water and a 30% TFE-water mixture.
• Peptide Stokes radii, dissociation constants, and mobility were measured across acidic pHapp (2.00–4.25).

Main Results:

• Stokes radii and acidic dissociation constants were determined for peptides.
• The reliability of semiempirical models for predicting peptide size and charge was assessed.
• Optimal predictive conditions for size and charge were identified at pHapp 2.00–2.25.
• Reliable predictive equations for peptide mobility were established.

Conclusions:

• Semiempirical models show varying reliability for peptide size and charge prediction.
• Peptide mobility can be reliably predicted using the charge-to-size ratio under specific acidic conditions.
• The TFE-water mixture did not significantly alter the optimal predictive conditions compared to water.