Histone H3 (1-20) K4Me3, K9Ac-GG-[Lys(5-FAM)] is derived from Histone 3 (H3) which is one of the four core histones fundamental for compacting eukaryotic DNA into the nucleosome. Lysine 4 of Histone H3 (1-20) K4Me3, K9Ac-GG-[Lys(5-FAM)] has been tri-methylated, lysine 9 has been acetylated and the C-terminal has been labelled with 5-Carboxyfluorescein (5-FAM), a widely used green, fluorescent tag. Additionally, this peptide contains an uncharged C-terminal amide.

LD: Histone H3 (1-20) K4Me3, K9Ac-GG-[Lys(5-FAM)] is derived from Histone 3 (H3) which is one of the four core histones (H2A, H2B, H3 and H4) fundamental in compacting eukaryotic DNA into the nucleosome. The nucleosome arises when 147 base pairs of DNA wrap around a H3-H4 tetramer and two H2A-H2B dimers, forming the histone octamer core. Both H4 and H3 are highly conserved and perform roles in binding to segments of DNA which enter and leave the nucleosome and in chromatin formation. Similar to the other core histone, H3 has a globular domain and a flexible N-terminal domain, “histone tail” which can undergo modifications such as acetylation, methylation, phosphorylation and ubiquitination. Due to histones containing a large number of lysine and arginine residues they have a positive net charge which interacts in an electrostatic manner with the negatively charged phosphate groups in DNA. The transcriptional activation or silencing of the chromatin is controlled by ATP-dependent chromatin remodelling factors and histone modifying enzymes which target histone proteins. Both processes function to alter the positioning of the nucleosome, allowing the DNA it to be either available or inaccessible to the transcription machinery.

The lysine at position 4 of this peptide has been tri-methylated and it is implicated in studies that this modification may remodel the chromatin so that it is more accessible to transcription factors, which may ultimately increase the level of gene expression. The lysine at position 9 has been acetylated, which neutralizes the positive charge on the amino acid, loosening the chromatin structure. This alteration to the accessibility of chromatin promotes the initiation of transcription.

Additionally, Histone H3 (1-20) K4Me3, K9Ac-GG-[Lys(5-FAM)] has a C-terminal GKK linker labelled with 5-Carboxyfluorescein (5-FAM), a widely used green fluorescent tag. This peptide also has an uncharged C-terminal amide.