[Lys(Me2)9]-Histone H3 (1-21)-K(Biotin)

Product Name: [Lys(Me2)9]-Histone H3 (1-21)-K(Biotin)

Sequence One Letter Code: ARTKQTAR-K(Me2)-STGGKAPRKQLA-K(Biotin)

Sequence Three Letter Code: H-Ala-Arg-Thr-Lys-Gln-Thr-Ala-Arg-Lys*-Ser-Thr-Gly-Gly-Lys-Ala-Pro-Arg-Lys-Gln-Leu-Ala-Lys(Biotin)-OH (Lys*=di-methylated Lys)

Molecular Weight: 2637.3

Purity: 95%

Form: Lyophilized

Storage Conditions: - 20 °C

Research Area: epigenetics

Source / Species: human

Conjugation: Conjugated

Conjugation Type: Biotins

Code Nacres: NA.26

Application: This peptide corresponds to histone H3 residues 1–21 and is dimethylated at lysine 9 (H3K9me2), a modification associated with transcriptional repression and heterochromatin formation. The C-terminal biotin tag enables affinity capture using streptavidin-based systems for pull-down and interaction assays. H3K9 dimethylation plays a pivotal role in epigenetic gene silencing and recruitment of heterochromatin-associated proteins. This peptide is well suited for studying methyl-lysine reader proteins, chromatin-binding complexes, and antibody specificity. It provides a defined substrate for biochemical analyses of chromatin organization and transcriptional repression mechanisms.

Current Research: Epigenetic regulation of gene expression depends heavily on post-translational modifications of histone proteins. Among these modifications, lysine methylation on histone H3 plays a key role in defining transcriptionally active and repressive chromatin states. One of the most well-characterized repressive marks is dimethylation of lysine 9 on histone H3 (H3K9me2), which is strongly associated with heterochromatin formation and epigenetic gene silencing. Synthetic peptides that reproduce histone sequences with defined modifications are widely used to study the molecular mechanisms underlying chromatin regulation. The biotinylated H3 (1–21) K9me2 peptide provides a defined reagent for analyzing protein interactions, chromatin-binding complexes, and transcriptional repression pathways. Histone H3 N-Terminal Tail as a Regulatory Platform Histone H3 is a core component of the nucleosome, the structural unit around which DNA is wrapped to form chromatin. The N-terminal tail of histone H3 extends outward from the nucleosome and contains several lysine residues that are frequently modified by methylation, acetylation, and phosphorylation. These modifications serve as regulatory signals that influence chromatin structure and gene expression. The specific combination of modifications present on histone tails forms part of the epigenetic landscape, determining whether chromatin regions remain transcriptionally active or become transcriptionally silent. The segment encompassing residues 1–21 of histone H3 includes lysine 9, one of the most important methylation sites involved in transcriptional repression. Biological Significance of H3K9 Dimethylation Dimethylation at lysine 9 of histone H3 (H3K9me2) is commonly associated with regions of chromatin that exhibit reduced transcriptional activity. This modification is frequently enriched within heterochromatin, a tightly packed form of chromatin that restricts access of transcriptional machinery to DNA. H3K9 methylation can occur in different states—mono-, di-, or trimethylation—each associated with specific chromatin contexts. The dimethylated form is often linked to facultative heterochromatin and gene silencing within euchromatic regions. Unlike acetylation, methylation does not change the charge of the lysine residue. Instead, it alters the chemical surface of the histone tail, creating binding sites for specialized methyl-lysine reader proteins that recognize the modified residue. Recruitment of Heterochromatin-Associated Proteins One of the primary functions of H3K9 methylation is to recruit proteins involved in heterochromatin formation. Proteins such as heterochromatin protein 1 (HP1) contain chromodomains that selectively bind methylated lysine residues on histone H3. Binding of these reader proteins initiates a cascade of events that promotes chromatin compaction and gene repression. The recruitment of chromatin-binding complexes stabilizes heterochromatin structure and helps maintain transcriptionally silent genomic regions. Through these mechanisms, H3K9me2 contributes to the establishment and maintenance of epigenetic gene silencing, ensuring that certain genes remain inactive in specific cellular contexts. Structural Design of the Biotinylated Peptide The H3 (1–21) K9me2 peptide replicates the N-terminal region of histone H3 while incorporating a site-specific dimethylation at lysine 9. This design preserves the natural sequence context surrounding the modification, allowing proteins that recognize H3K9 methylation to interact with the peptide as they would with the native histone tail. At the C-terminus, the peptide contains a biotin tag, which enables efficient immobilization through the strong interaction between biotin and streptavidin. Streptavidin-coated beads, plates, or matrices can be used to capture the peptide and associated binding partners in affinity-based assays. This configuration provides a stable platform for investigating protein–histone interactions under controlled biochemical conditions. Applications in Pull-Down and Interaction Assays Biotinylated histone peptides are widely used in pull-down experiments designed to identify proteins that interact with specific histone modifications. In a typical assay, the peptide is immobilized via streptavidin and incubated with nuclear extracts or purified proteins. Proteins that recognize the H3K9me2 modification bind to the peptide and can be isolated for analysis using techniques such as immunoblotting or mass spectrometry. These experiments help identify chromatin-binding proteins and regulatory complexes involved in transcriptional repression. Such interaction studies are crucial for understanding how histone methylation signals are interpreted within chromatin regulatory networks. Studying Methyl-Lysine Reader Proteins The peptide is particularly useful for investigating methyl-lysine reader proteins, including chromodomain-containing proteins and other methylation-sensitive domains. By providing a defined binding substrate, the peptide allows researchers to measure binding affinity, specificity, and structural recognition of the H3K9me2 mark. These studies contribute to understanding how chromatin readers distinguish between different methylation states and how these interactions regulate gene expression. Validation of Modification-Specific Antibodies Another important application of modified histone peptides is validation of antibodies that recognize specific histone methylation states. Because histone lysines can exist in multiple methylation states, antibodies must demonstrate high specificity to accurately detect the intended modification. The H3K9me2 peptide serves as a reference reagent for evaluating antibody performance in assays such as ELISA, western blotting, and chromatin immunoprecipitation (ChIP). Using defined peptide standards helps ensure reliable detection of histone modifications in experimental samples. Conclusion The biotinylated H3 (1–21) peptide containing dimethylated lysine 9 (H3K9me2) provides a powerful biochemical tool for investigating chromatin-mediated gene repression. By reproducing a key histone modification associated with heterochromatin formation, the peptide enables detailed study of methyl-lysine recognition, chromatin-binding complexes, and epigenetic silencing mechanisms. Through applications in affinity pull-down assays, reader protein interaction studies, and antibody validation, this reagent supports research aimed at understanding how histone methylation shapes chromatin organization and transcriptional regulation.