Sample preparation procedure for mass spectrometric analysis of plant histones

The protocol for preparing samples of plant histones prior to LC-MS/MS analysis was established, using a filter-aided sample preparation (FASP) technique to remove natural contaminants and chemical additives incompatible with MS-based procedures. The protocol consists of nuclei isolation, histone extraction into acidic solvent, protein propionylation and on-membrane digestion, then peptide propionylation in solution. Two variants of the derivatization protocol, in-solution propionylation in the vial (PROP-in-SOL) and propionylation on the filter unit (PROP-on-FILTER), were compared by efficiency of the labeling and by abundance of identified histone peptide forms.