Quantitative profile of lysine methylation and acetylation of histones by LC-MS/MS

Histone post-translational modifications (PTMs), as the histone code assumes, are related with regulation of gene transcription, an important mechanism of cells in the differentiation process. Many PTMs are simultaneously present in histone proteins, and changes in the PTM stoichiometric ratios can have several effects, like changes in the chromatin structure leading to a transcriptionally active or repressive state. Significant progresses were made to map variations of histone PTMs by mass spectrometry (MS), and although many protocols were developed there are still some drawbacks. Incomplete and side reactions were identified, which can directly affect the quantification of histone PTMs, because both (incomplete and side reactions) can be misinterpreted as endogenous histone post translational modifications. Therefore, a protocol for derivatization of histones with no noticeable undesired reactions (