Improved mass spectrometric detection of acidic peptides by variations in the functional group pKa values of reverse micelle extraction agents (original) (raw)
* Corresponding authors
a Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, USA
b Molecular and Cellular Biology Program, University of Massachusetts, Amherst, Massachusetts 01003, USA
c Center for Bioactive Delivery, Institute for Applied Life Sciences, University of Massachusetts, Amherst, Massachusetts 01003, USA
E-mail: thai@chem.umass.edu, rwvachet@chem.umass.edu
Abstract
Polymeric reverse micelles can be used to selectively extract peptides from complex mixtures via a two-phase extraction approach. In previous work, we have shown that the charge polarity of the hydrophilic functional group that is in the interior of the reverse micelle dictates the extraction selectivity. To investigate how the extraction is influenced by the inherent p_K_a of the functional group, we designed and tested a series of polymeric reverse micelles with variations in the hydrophilic functional group. From this series of polymers, we find that the extraction capability of the reverse micelles in an apolar phase is directly related to the aqueous phase p_K_a of the interior functional group, suggesting that the functional groups maintain their inherent chemistry even in the confined environment of the reverse micelle interior. Because these functional groups maintain their inherent p_K_a in the reverse micelle interior, they provide predictable extraction selectivity upon changes in aqueous phase pH. We exploit this finding to demonstrate that sulfonate-containing polymers can be used to remove basic peptides from complex mixtures, thereby allowing the improved detection of acidic peptides. Using these new materials, we also demonstrate a new means of isoelectric point (pI) bracketing that allows the mass spectrometric detection of peptides with a defined and narrow range of pI values.
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Article information
DOI
https://doi.org/10.1039/C7AN02094E
Article type
Paper
Submitted
27 Dec 2017
Accepted
14 Feb 2018
First published
15 Feb 2018
Download Citation
Analyst, 2018,143, 1434-1443
Permissions
Improved mass spectrometric detection of acidic peptides by variations in the functional group p_K_a values of reverse micelle extraction agents
B. Zhao, M. A. C. Serrano, M. Wang, T. Liu, M. R. Gordon, S. Thayumanavan and R. W. Vachet,Analyst, 2018, 143, 1434DOI: 10.1039/C7AN02094E
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