Protein Phosphorylation

Resin Elution Selectivity

Product No: P 9740

Resin Elution Selectivity - MALDI-MS

Figure 2. MALDI mass spectra of A) Crude ß-casein tryptic digest (113 pmol/µL) prior to loading on the PHOS-Select Resin and B)-E) purified phosphopeptides after elution from the PHOS-Select Resin under various elution conditions. Eluents were as follows: B) 0.15 M NH4OH, C) 0.4 M NH4OH, neutralized with formic acid prior to analysis, D) 0.15 M NH4OH, 25% ACN, and E) 5% formic acid, 25% ACN.


Binding Capacity Study
Species Molecular
Weight (Da)
Format
Plate
(nmol/well)
Resin
(µmol/mL)
4-methylumbelliferyl
phosphate (MUP)
256.14 0.9 4.5
Monophosphopeptide
(ß-casein)
2061.96 0.5 8.0
Tetraphosphopeptide
(ß-casein)
3122.92 1.0 5.5
Binding capacities for the two formats were determined using purified phosphorylated molecules. Binding of MUP was determined via a fluorescence assay. Binding of the mono and tetraphosphopeptides was determined using HPLC-MS analysis.