Histone H3 (1-25), amide is a N-terminal peptide fragment of histone H3 that serves as a substrate for histone methyltransferases (HMTs). It can be utilized to identify the substrate for HMTs. Compared to histone H3 (15-39) and full-length histone H3, Histone H3 (1-25), amide proves to be more efficient as a substrate for HMT G9a.