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Capillary Electrophoresis-based Hydrogen/Deuterium Exchange for Conformational Characterization of Proteins with Top-down Mass Spectrometry
Published on: June 8, 2021
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Electromembrane extraction of peptides based on hydrogen bond interactions
Samira Dowlatshah1, Frederik André Hansen1, Chen Zhou2
1Department of Pharmacy, University of Oslo, P.O Box 1068 Blindern, 0316, Oslo, Norway.
Analytica Chimica Acta
|July 31, 2023
Summary
This study introduces a novel electromembrane extraction method for peptides using tri(pentyl) phosphate as a carrier-free liquid membrane. This approach enhances stability and selectivity through hydrogen bonding interactions, avoiding electrolysis issues.
Area of Science:
- Analytical Chemistry
- Separation Science
Background:
- Electromembrane extraction (EME) traditionally uses ionic carriers in liquid membranes for peptide transfer.
- Ionic carriers increase membrane conductivity, leading to accelerated electrolysis and pH instability.
- This limits the efficiency and reliability of EME for peptide analysis.
Purpose of the Study:
- To develop a carrier-free electromembrane extraction method for peptides.
- To investigate the use of organic solvents as pure liquid membranes in EME.
- To identify the primary interaction mechanisms responsible for peptide transfer in the absence of ionic carriers.
Main Methods:
- Screening of various organic solvents as liquid membranes for EME of peptides.
- Selection and evaluation of tri(pentyl) phosphate for its extraction efficiency and operational stability.
- Testing the extraction of 16 different model peptides, focusing on charge and polarity characteristics.
- Analysis of extracted peptides from human blood plasma using LC-MS/MS.
Main Results:
- Tri(pentyl) phosphate demonstrated high mass transfer and operational stability as a carrier-free liquid membrane.
- Selective extraction of peptides with a net charge of +1 and limited polar side chains was achieved.
- Hydrogen bonding between the tri(pentyl) phosphate (acceptor) and protonated peptides (donors) was identified as the key interaction.
- Exhaustive extraction of specific peptides (leu-enkephalin, met-enkephalin, endomorphin) from human blood plasma was successful.
- Linear calibration curves (r² > 0.99) and good precision (RSD < 12%) were obtained.
Conclusions:
- Carrier-free EME using tri(pentyl) phosphate enables selective peptide extraction based on hydrogen bonding.
- This method overcomes the limitations of electrolysis and pH drifting associated with traditional EME.
- The approach is suitable for analyzing small, low-polarity peptides in complex matrices like blood plasma.
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