An easy and straightforward synthesized nano calcium phosphate for highly capture of multiply phosphorylated peptides

Multisite phosphorylation of proteins regulates various cellular life activities, however, the capture of low abundance multi-phosphopeptides from biosamples and identification of phosphorylation sites are largely limited due to the limited enrichment materials and their unclear interactions with multi-phosphopeptides. Here we propose using two cheap raw materials (CaCl2·2H2O and Na2HPO4·12H2O) in 10 min at room temperature to synthesize the structurally simple Nanometric Calcium Phosphate (CaP) to resolve this challenge. The current results showed that the "simple" CaP has good selection specificity, high sensitivity and stability for multi-phosphopeptides enrichment and the identification of phosphorylation sites, which facilitate the popularization and application of phosphoproteomics research. Further, the interaction of CaP and multi-phosphopeptides were qualitatively characterized at the molecular/atomic level and the high affinity between them was quantified by the isothermal titration microcalorimeter based on the laws of thermodynamics. The results indicated that the interaction was a spontaneous (ΔG < 0) exothermic reaction with enthalpy reduction (ΔH < 0) and driven mainly by hydrogen bond and electrostatic interaction process.