Synthesis of diazo functionalized solid supports and their application towards the enrichment of phosphorylated...

We describe herein the synthesis and application of a range of diazo-functionalized materials as platforms for the solid phase enrichment of phosphorylated peptides from protein digests. Diazo-functionalized solid phase resins are employed to bind covalently and specifically with the phosphate moiety of a peptide substrate, allowing for non-phosphorylated peptides to be efficiently removed by filtration. The technique described herein is compatible with enrichment of phospho-serine, threonine and tyrosine residues and was used to successfully enrich phosphorylated substrates from beta-casein and ovalbumin digests in low-picomolar quantities.