Phosphopeptide Enrichment by Immobilized Metal Affinity Chromatography.

Research output: Contribution to journalArticle


Immobilized metal affinity chromatography (IMAC) has been the method of choice for phosphopeptide enrichment prior to mass spectrometric analysis for many years and it is still used extensively in many laboratories. Using the affinity of negatively charged phosphate groups towards positively charged metal ions such as Fe(3+), Ga(3+), Al(3+), Zr(4+), and Ti(4+) has made it possible to enrich phosphorylated peptides from peptide samples. However, the selectivity of most of the metal ions is limited, when working with highly complex samples, e.g., whole-cell extracts, resulting in contamination from nonspecific binding of non-phosphorylated peptides. This problem is mainly caused by highly acidic peptides that also share high binding affinity towards these metal ions. By lowering the pH of the loading buffer nonspecific binding can be reduced significantly, however with the risk of reducing specific binding capacity. After binding, the enriched phosphopeptides are released from the metal ions using alkaline buffers of pH 10-11, EDTA, or phosphate-containing buffers.Here we describe a protocol for IMAC using Fe(3+) for phosphopeptide enrichment. The principles are illustrated on a semi-complex peptide mixture.


  • Tine Thingholm
  • Martin R Larsen
External organisations
  • University of Southern Denmark
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Cell and Molecular Biology
Original languageEnglish
Pages (from-to)123-133
JournalMethods in Molecular Biology
Publication statusPublished - 2016
Publication categoryResearch