HistoneH3 (1-25), amide is a N-terminal peptide fragment of histoneH3 that serves as a substrate for histone methyltransferases (HMTs). It can be utilized to identify the substrate for HMTs. Compared to histoneH3 (15-39) and full-length histoneH3, HistoneH3 (1-25), amide proves to be more efficient as a substrate for HMT G9a.