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Mol Cell Proteomics. 2007 Jun;6(6):1103-9. Epub 2007 Feb 23.

Phosphopeptide enrichment by aliphatic hydroxy acid-modified metal oxide chromatography for nano-LC-MS/MS in proteomics applications.

Author information

1
Institute for Advanced Biosciences, Keio University, Tsuruoka 997-0017, Japan.

Abstract

We developed novel methods for phosphopeptide enrichment using aliphatic hydroxy acid-modified metal oxide chromatography (MOC). Titania and zirconia were successfully applied to enrich phosphopeptides with the aid of aliphatic hydroxy acids, such as lactic acid and beta-hydroxypropanoic acid, to reduce the interaction between acidic non-phosphopeptides and the metal oxides. These methods removed the vast majority of non-phosphopeptides from phosphoprotein standard digests, and large numbers of phosphopeptides could be readily identified. The methods were coupled with nano-LC-MS/MS systems without difficulty. Recovery of phosphopeptides in MOC varied greatly from peptide to peptide, ranging from a few percent to 100%, and the average was almost 50%. Repeatability and linearity were satisfactory. In an examination of the cytoplasmic fraction of HeLa cells, more than 1000 phosphopeptides were identified using lactic acid-modified titania MOC and beta-hydroxypropanoic acid-modified zirconia MOC, respectively. The overlap between phosphopeptides enriched by these two methods was 40%, and the combined results provided 1646 unique phosphopeptides. To our knowledge, this is the first successful application of a single MOC-based approach to phosphopeptide enrichment from complex biological samples such as cell lysates.

PMID:
17322306
DOI:
10.1074/mcp.T600060-MCP200
[Indexed for MEDLINE]
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