Protein phosphorylation is one of the most biologically relevant modifications
and is involved in many eukaryotic and prokaryotic cellular signaling
processes. It is estimated that one third of human proteins are phosphorylated
Phosphorylation events are characterized by isolating the phosphopeptides
and mapping their phosphorylated sites. Mass spectrometry (MS) methods
have become powerful tools for characterizing and identifying protein
phosphorylation events.
Prior to MS analysis, proteins are digested with specific proteases, such as
trypsin, chymotrypsin, Lys-C, Glu-C, Asp-N and Lys-N. The enrichment of
phopshopeptides from digested protein samples typically is achieved by
immobilized metal affinity chromatography (IMAC) using Fe3+ and Ga3+.
Although these IMAC methods are very efficient in enriching phosphopeptides,
they also result in significant amounts of nonspecific peptide binding.
To provide an efficient phosphopeptide enrichment method with both high
specificity and low nonspecific binding, we developed the PhosphoCatch™
Phosphopeptide Enrichment System. This system contains a combination of two
resins: zirconium oxide (ZrO2) and titanium oxide (TiO2). Since these metal
oxides differentially enrich mono- and multiphosphorylated peptides,
their individual use may result in a biased representation of the
phosphopeptides in a given sample. The combination of both metal oxides in
the PhosphoCatch™ Phosphopeptide Enrichment System enables a more
accurate sampling of both the mono- and multiphosphorylated peptides
in a fast and convenient format.
For more information visit the Promega web site.
