Analysis of Histone Lysine Methylation Using Mass Spectrometry

Abstract

Histones are highly basic proteins which when digested by trypsin are hard to analyze using mass spectrometry. Because histones are basic nuclear proteins, a nuclei prep followed by acid extraction is the best purification strategy to increase overall abundance of purified histones. Blocking the lysine residues and cleaving with trypsin is a useful technique to increase detection of histone peptides using MudPIT. In particular, carbamylation and propionylation are the best two methods to block lysine residues. Using both propionylation and carbamylation along with no treatment has been shown to increase the identification of unmodified and modified histone peptides when coupled with MudPIT analysis.