[Lys(Ac)9] – Histone H3 (1-21)-GGK(Biotin)-NH2

Product Name: [Lys(Ac)9] - Histone H3 (1-21)-GGK(Biotin)-NH2

Sequence One Letter Code: ARTKQTAR-K(Ac)-STGGKAPRKQLA-GGK(Biotin)-NH2

Sequence Three Letter Code: H-Ala-Arg-Thr-Lys-Gln-Thr-Ala-Arg-Lys(Ac)-Ser-Thr-Gly-Gly-Lys-Ala-Pro-Arg-Lys-Gln-Leu-Ala-Gly-Gly-Lys(Biotin)-NH2

Molecular Weight: 2764.4

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 biotinylated peptide corresponds to residues 1–21 of histone H3 and contains an acetyl modification at lysine 9 (H3K9ac), a well-characterized epigenetic mark associated with transcriptionally active chromatin and enriched near transcription start sites. H3K9 acetylation contributes to an open chromatin configuration that supports transcription initiation and elongation by facilitating the recruitment of transcriptional machinery and acetyl-lysine reader proteins. The peptide incorporates a C-terminal glycine–glycine (GG) linker followed by a biotinylated lysine, enabling stable immobilization on streptavidin-coated surfaces for affinity capture and interaction studies. This configuration supports pull-down assays, chromatin interaction analysis, and the investigation of proteins that specifically recognize acetylated histone tails, including bromodomain-containing factors. By replicating the native N-terminal sequence of histone H3 with a defined acetylation site, this peptide serves as a useful tool for epigenetics research, histone modification studies, and validation of antibodies targeting H3K9 acetylation.

Current Research: Epigenetic regulation plays a central role in controlling gene expression without altering the underlying DNA sequence. One of the most important mechanisms of epigenetic control involves post-translational modifications (PTMs) of histone proteins, which influence chromatin structure and transcriptional activity. Among these modifications, acetylation of lysine residues on histone H3 is strongly associated with transcriptionally active chromatin. In particular, acetylation at lysine 9 of histone H3 (H3K9ac) is widely recognized as a marker of active promoters and regulatory regions. Synthetic histone peptides containing defined modifications, such as the biotinylated H3K9ac peptide corresponding to residues 1–21 of histone H3, provide valuable tools for studying the molecular mechanisms of chromatin regulation and protein recognition of acetylated histone tails. Histone Acetylation and Chromatin Accessibility Histones form the structural foundation of chromatin by organizing DNA into nucleosomes. Each nucleosome consists of DNA wrapped around a histone octamer composed of two copies each of H2A, H2B, H3, and H4. The N-terminal tails of histones, including histone H3, extend outward from the nucleosome and are accessible to regulatory enzymes that introduce post-translational modifications. Histone acetylation is catalyzed by histone acetyltransferases (HATs), which transfer acetyl groups from acetyl-CoA to lysine residues on histone tails. This modification neutralizes the positive charge of lysine side chains, weakening electrostatic interactions between histones and the negatively charged DNA backbone. As a result, chromatin adopts a more relaxed and accessible conformation, allowing transcription factors and RNA polymerase to access gene regulatory regions. The dynamic balance between acetylation and deacetylation—regulated by HATs and histone deacetylases (HDACs)—plays a major role in controlling transcriptional activity and maintaining cellular identity. Functional Significance of H3K9 Acetylation Among the various histone acetylation sites, H3K9ac is one of the most extensively studied marks associated with active gene expression. Genome-wide chromatin profiling studies have shown that this modification is highly enriched near transcription start sites (TSS) and promoter regions of actively transcribed genes. H3K9 acetylation contributes to transcriptional activation through multiple mechanisms. First, it promotes chromatin accessibility, allowing transcription factors to bind DNA more efficiently. Second, it creates docking sites for specialized protein modules known as acetyl-lysine reader domains, such as bromodomains. Proteins containing these domains recognize acetylated lysines and recruit additional transcriptional machinery or chromatin remodeling complexes. Through these interactions, H3K9ac functions as a key signal linking histone modification patterns to the assembly of transcriptional regulatory complexes. Design of the Biotinylated H3K9ac Peptide To facilitate biochemical and structural studies of histone modifications, researchers often use synthetic peptides representing histone tail sequences with defined PTMs. The peptide described here corresponds to residues 1–21 of histone H3, which includes several regulatory lysine residues within the histone H3 N-terminal tail. In this peptide, lysine 9 is specifically acetylated, reproducing the H3K9ac epigenetic mark found in active chromatin regions. The peptide also incorporates a C-terminal glycine–glycine (GG) linker followed by a biotinylated lysine residue. This design allows the peptide to be immobilized efficiently on streptavidin-coated beads or surfaces, which form extremely stable interactions with biotin. The flexible glycine linker helps separate the histone sequence from the biotin tag, ensuring that the acetylated lysine remains accessible for interaction with binding proteins. Applications in Chromatin Interaction Studies Biotinylated histone peptides are widely used in pull-down assays designed to identify or characterize proteins that recognize specific histone modifications. In a typical experiment, the immobilized peptide is incubated with cell extracts or purified proteins. Proteins that bind to the acetylated histone sequence can then be captured and analyzed using techniques such as western blotting or mass spectrometry. These experiments help identify chromatin reader proteins that specifically interact with H3K9ac. Bromodomain-containing proteins are among the most well-known readers of acetylated histone lysines. Many of these proteins function as transcriptional coactivators or components of chromatin remodeling complexes, linking histone acetylation to gene activation. Studying Epigenetic Regulation and Enzyme Specificity In addition to protein interaction studies, the H3K9ac peptide can be used to investigate histone-modifying enzymes. For example, researchers can examine how histone acetyltransferases recognize histone substrates or how deacetylases interact with acetylated residues. Such studies help clarify how epigenetic marks are dynamically established and removed during transcriptional regulation. These peptide substrates also provide useful reagents for studying epigenetic signaling networks involved in development, differentiation, and disease. Antibody Validation and Assay Development Another important application of modified histone peptides is antibody validation. Antibodies targeting histone modifications must distinguish between closely related modifications and unmodified histones. Synthetic peptides containing defined modifications serve as precise standards for testing antibody specificity and sensitivity. For example, an antibody raised against H3K9ac can be evaluated by comparing its binding to acetylated and non-acetylated peptide variants. Such validation ensures reliable results in experiments such as chromatin immunoprecipitation (ChIP) or immunofluorescence. Supporting Epigenetics and Chromatin Research The biotinylated H3K9ac peptide provides a well-defined molecular tool for studying the functional consequences of histone acetylation. By replicating the native N-terminal sequence of histone H3 while incorporating a specific acetyl modification and affinity tag, this reagent enables controlled investigation of chromatin interactions, histone modification recognition, and transcription-associated epigenetic regulation. As research into chromatin biology continues to expand, reagents that model specific histone modifications remain essential for understanding how epigenetic marks influence gene expression and cellular behavior. The H3K9ac peptide therefore serves as a valuable resource for epigenetics research, chromatin interaction studies, and antibody validation efforts aimed at elucidating the molecular mechanisms underlying transcriptional control.