PTMScan^® Phospho-Enrichment IMAC Fe-NTA Magnetic Beads #20432

Immobilized metal affinity chromatography, or IMAC, has been widely used to enrich proteins and peptides from biological samples by binding to clusters of negative charge. Divalent transition metal ions Co²⁺, Cu²⁺, Ni²⁺, and Zn²⁺ are often used to purify proteins rich in poly-Histidine or Cysteine as well as proteins with metal affinity. Trivalent metal ions, Fe³⁺, Ga³⁺, Al³⁺, as well as Ti⁴⁺ and Zr⁴⁺ are commonly used for phosphopeptide enrichment for proteomic studies (1). Iminodiacetic acid (IDA) or nitrilotriacetic acid (NTA) are used for chelating the metal ions to agarose-coated beads. In comparison studies, NTA has been shown to perform better than IDA at selectively capturing and identifying more phosphopeptides. Ga³⁺ and Fe³⁺ are comparable with respect to the number of phosphopeptides identified (2). Compared to metal oxide affinity chromatography (MOAC) using TiO₂, Fe³⁺ IMAC performed marginally better with TiO₂ having a preference for acidic phosphopeptides (pI > 4) relative to Fe³⁺ which preferred less acidic peptides (pI < 4) (3). The PTMScan^® Fe-NTA Magnetic Beads offer an efficient tool for phosphopeptide enrichment with little or no bias for phospho-residue context. They can be employed independently or in conjunction with immunoaffinity based enrichment to complement any PhosphoScan^® LC-MS/MS proteomic study.