In Vitro Assays to Measure Histone Methyltransferase Activity Using Different Chromatin Substrates.

In vitro histone modification (HM) assays are used to characterize the activity of chromatin-modifying enzymes. These assays provide information regarding the modification sites on histones, the product specificity, and the impact of other histone or nucleotide modifications on enzyme activity. In particular, histone methyltransferase (HMT) assays have been instrumental in elucidating the activity and site specificity of many plant HMT enzymes. In this chapter, we describe a general protocol that can be used to perform HMT assays using different chromatin substrates, detection methods, and enzymes directly purified from plant material or heterologous sources.