<p>Synthetic oligonucleotides containing the SNP are phosphorylated, polymerized and subsequently strand-specifically desthiobiotin-labeled. The immobilized DNA fragments are incubated with either light or heavy extract. After removal of unbound proteins, bead fractions are combined and DNA-protein complexes are eluted with biotin. The eluate is precipitated, digested and analyzed by single-run, high resolution, quantitative mass spectrometry. Specific interaction partners result in a ratio different from 1∶1, demonstrating specific enrichment at one variant of the single nucleotide polymorphism.</p
