[Lys(Ac)18]-Histone H3 (1-21)-GGK(Biotin)-NH2

Product Name: [Lys(Ac)18]-Histone H3 (1-21)-GGK(Biotin)-NH2

Sequence One Letter Code: ARTKQTARKSTGGKAPR-K(Ac)-QLA-GGK(Biotin)-NH2

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

Molecular Weight: 2764.4

Purity: 95%

Form: Lyophilized

Storage Conditions: - 20 °C

Research Area: Cancer Disease Research

Source / Species: human

Conjugation: Conjugated

Conjugation Type: Biotins

Code Nacres: NA.26

Application: This peptide corresponds to histone H3 residues 1–21 and is acetylated at lysine 18, a modification associated with transcriptional activation and cancer prognosis. A C-terminal glycine–glycine linker followed by a biotinylated lysine enables affinity capture using streptavidin-based systems. H3K18 acetylation has been correlated with clinical outcomes in prostate, lung, and kidney cancers and plays a role in chromatin accessibility and transcriptional regulation. This peptide is suitable for studying histone acetyltransferase specificity, bromodomain-mediated recognition, and epigenetic regulation in oncogenic contexts. It is also valuable for antibody validation and reader protein interaction assays.

Current Research: Epigenetic modifications of histone proteins play a fundamental role in regulating gene expression, chromatin structure, and cellular identity. Among the most extensively studied modifications is histone acetylation, a reversible process that influences chromatin accessibility and transcriptional activity. One modification of particular interest is acetylation of lysine 18 on histone H3 (H3K18ac), which has been strongly associated with transcriptional activation and has emerged as a potential biomarker in several cancers. Synthetic peptides representing histone tail regions with defined post-translational modifications provide powerful tools for dissecting these epigenetic mechanisms. A biotinylated H3K18ac peptide corresponding to residues 1–21 of histone H3 enables detailed investigation of histone modification recognition, enzymatic regulation, and chromatin-associated protein interactions. Histone Acetylation and Chromatin Regulation Histones form the core of nucleosomes, the basic structural units of chromatin. Each nucleosome consists of DNA wrapped around an octamer of histone proteins, including H2A, H2B, H3, and H4. The N-terminal tails of histones extend outward from the nucleosome and are subject to a wide range of post-translational modifications, such as acetylation, methylation, phosphorylation, and ubiquitination. These chemical modifications collectively contribute to the “histone code,” a regulatory system that modulates chromatin structure and gene transcription. Acetylation of lysine residues is mediated by histone acetyltransferases (HATs), which transfer an acetyl group from acetyl-CoA to the ε-amino group of lysine. This modification neutralizes the positive charge of lysine residues, weakening their interaction with negatively charged DNA. As a result, chromatin becomes more accessible to transcription factors and transcriptional machinery, generally promoting gene activation. Conversely, histone deacetylases (HDACs) remove acetyl groups, restoring chromatin compaction and transcriptional repression. Functional Importance of H3K18 Acetylation Among histone acetylation sites, lysine 18 on histone H3 has attracted particular attention due to its regulatory and clinical significance. H3K18 acetylation is commonly associated with active chromatin regions and transcriptionally engaged genes. The modification can recruit chromatin-binding proteins that contain specialized recognition modules, such as bromodomains, which specifically bind acetylated lysine residues. Beyond its role in transcriptional regulation, H3K18ac has been linked to cancer biology and disease prognosis. Altered levels of this modification have been observed in several malignancies, including prostate, lung, and kidney cancers. In some clinical studies, reduced global levels of H3K18 acetylation have been associated with poor patient outcomes, suggesting that the modification may serve as a biomarker reflecting epigenetic dysregulation in tumor cells. Because of these associations, understanding how H3K18 acetylation is established, recognized, and interpreted by cellular machinery has become an important area of research in epigenetics and cancer biology. Design of the Biotinylated H3K18ac Peptide Synthetic histone peptides are widely used to model specific post-translational modifications in a controlled experimental format. The peptide described here corresponds to residues 1–21 of histone H3, a region encompassing several important regulatory lysine residues and representing the accessible N-terminal tail of the histone protein. In this peptide, lysine 18 is specifically acetylated, faithfully reproducing the H3K18ac modification observed in chromatin. To facilitate biochemical assays, the peptide also includes a C-terminal glycine–glycine linker followed by a biotinylated lysine residue. This design enables efficient capture using streptavidin-based affinity systems, a widely used approach for immobilizing biotin-labeled molecules. The glycine linker provides flexibility and spatial separation between the histone sequence and the biotin tag, helping preserve accessibility of the modified lysine residue for interacting proteins. Applications in Epigenetic Research Biotinylated histone peptides are commonly used in pull-down assays and binding studies to investigate interactions between histone modifications and chromatin-associated proteins. By immobilizing the peptide on streptavidin-coated beads or surfaces, researchers can capture proteins that specifically recognize the H3K18ac modification. One major application involves studying bromodomain-containing proteins, which function as “reader” modules that detect acetylated lysine residues on histones. Identifying which bromodomains bind to H3K18ac can help clarify how transcriptional regulatory complexes are recruited to chromatin. The peptide is also useful for investigating histone acetyltransferase substrate specificity. Enzymatic assays can compare how different HAT enzymes modify histone sequences and determine how acetylation at specific sites influences downstream chromatin signaling. Antibody Validation and Interaction Studies Another important application of the H3K18ac peptide is antibody validation. Antibodies designed to detect histone modifications must exhibit high specificity for the modified residue. Synthetic peptides containing defined modifications provide reliable standards for testing antibody binding and ensuring that antibodies distinguish between acetylated and unmodified lysine residues. In addition, the peptide can be used in protein interaction assays, allowing researchers to identify or characterize proteins that selectively bind the H3K18ac modification. Such studies contribute to mapping the networks of epigenetic regulators that control gene expression. Advancing Epigenetic and Cancer Research As interest in epigenetic regulation continues to grow, tools that precisely model histone modifications are increasingly important. The biotinylated H3K18ac peptide offers a versatile platform for investigating how acetylation at lysine 18 influences chromatin structure, transcriptional regulation, and disease-related epigenetic changes. By enabling studies of enzyme specificity, reader protein recognition, and modification-dependent interactions, this peptide supports research into the molecular mechanisms that connect histone acetylation with gene regulation and oncogenic transformation. Such insights may ultimately contribute to improved understanding of epigenetic regulation and the development of therapeutic strategies targeting chromatin-modifying pathways.