Insights into Chemoselectivity Principles in Metal Oxide Affinity Chromatography Using Tailored Nanocast Metal Oxide Microspheres and Mass Spectrometry-Based Phosphoproteomics

A1 Journal article (refereed)


Internal Authors/Editors


Publication Details

List of Authors: Alexander Leitner, Motolani Sakeye, Christian Zimmerli, Jan-Henrik Smått
Publisher: Royal Society of Chemistry
Publication year: 2017
Journal: Analyst
Volume number: 142
Issue number: 11
Start page: 1993
End page: 2003
eISSN: 1364-5528


Abstract

The ability to comprehensively characterize biological samples,
including tissues and body fluids, opens up new possibilities to
diagnose and treat diseases and to better understand fundamental
biological processes. For this purpose, suitable experimental workflows
need to be designed. In this context, materials with particular
chemoselective properties are used for the enrichment of certain classes
of (bio)molecules. Metal oxides such as titanium dioxide have become
the materials of choice for the large-scale study of protein
phosphorylation in phosphoproteomics. Despite their widespread use, the
main factors influencing their performance (for example, affinity and
specificity) are not completely understood. This understanding is,
however, crucial to develop improved materials and methods. Here, we
used the nanocasting method to prepare microspheres of seven metal
oxides with comparable textural properties, allowing an objective
comparison of the materials and their binding properties. We evaluated
these materials with samples of different complexity, ranging from
synthetic peptides to whole cell lysates, using liquid
chromatography-tandem mass spectrometry as a readout. A set of more than
7000 identified phosphopeptides allowed us to study differences between
the metal oxide sorbents in detail. Importantly, the performance of the
affinity materials was found to be mainly correlated with the oxides’
isoelectric points (IEPs), with the materials that enriched the highest
number of phosphopeptides having an IEP of around 6. This included the
widely used TiO2 and ZrO2, but also In2O3
that was not previously known to possess affinity to phosphates. This
finding supports the conclusion that the IEP has a stronger influence
than the particular type of metal oxide and contrasts earlier reports
that compared a limited number of materials with often unknown textural
properties. Taken together, we introduce new metal oxides suitable for
phosphopeptide enrichment, provide deeper insight into the properties
that affect their performance, and offer a strategy to optimize
enrichment protocols and materials.


Last updated on 2019-13-11 at 04:22