ssK36, a peptide super-substrate for the histone methyltransferase SET domain-containing protein 2 (SETD2), is derived from histone H3 lysine 36 (H3K36) amino acids 29-43, with modifications at positions 31, 32, 36, 37, and 39. It undergoes methylation at a rate 70 times greater and 290 times faster than the unmodified H3K36 (29-43) in cell-free assays.