Selective enrichment of phosphopeptides by porous SnO<sub>2</sub> — ASN Events

Selective enrichment of phosphopeptides by porous SnO2 (#24)

Liping Li 1 , Yu Bai 1 , Huwei Liu 1
  1. Department od Chemistry, Peking University, Beijing, China

As one of the most important post-translational modifications, protein phosphorylation regulates various biological functions and involves in several diseases including cancer.[1] While phosphoproteomics attracts increasing interest, the detection of phosphorylated proteins/peptides by mass spectrometry (MS) is still challenging due to their low abundance, high dynamic range and poor ionization efficiency. Currently metal oxide affinity chromatography (MOAC) is considered more applicable[2] compared to other pre-treatment strategies. Various metal oxides have been proposed as affinity probes (APs), and among them SnO2 is considered as a selective and effective material[2].

Recently we applied porous SnO2 spheres with large surface area and high activity on phosphopeptide enrichment, and compared their performance with non-porous SnO2 and commercial TiO2. In a typical enrichment process the protein digests were incubated with the MOAC materials in a batch mode, and then the eluted peptides were analyzed by MALDI-TOF MS (matrix-assisted laser desorption/ionization-time of flight mass spectrometry). The mass spectra showed that better results could be obtained using porous SnO2 in both sensitivity and real sample analysis. For tryptic digests of β-casein, when the concentration was as low as 4×10-10 M, three phosphopeptides can still be detected after enrichment by porous SnO2.

[1] Stern, D. F. Phosphoproteomics. Experimental and Molecular Pathology, 2001, 70 (3), 327-331.
[2] Leitner, A. Phosphopeptide enrichment using metal oxide affinity chromatography. Trac-Trends in Analytical Chemistry, 2010, 29 (2), 177-185.