[Selective enrichment of phosphopeptides with aspartic acid based immobilized metal ion affinity chromatography...

A natural amino acid, aspartic acid, was modified to bind to silica microspheres with a click chemistry method (-Click Asp).The modified Click Asp microspheres were further modified by incorporating Fe³⁺ ions, resulting in Fe³⁺ and Click Asp based immobilized ion affinity chromatography (IMAC)(Fe³⁺-Click Asp).The prepared materials were characterized using Fourier transform infrared spectrometry, X-ray photoelectron spectrometry, and scanning electron microscopy, and it was confirmed that Fe³⁺-Click Asp was successfully prepared.Subsequently, the Fe³⁺-Click Asp microspheres were used to enrich phosphopeptides from tryptic digests of proteins and milk.It was found that the phosphopeptides could be selectively enriched with this material.This study describes a novel material and enrichment method for phosphoproteomics.