[Lys(Ac)27]-Histone H3 (21-43)-GGK(Biotin)

Product Name: [Lys(Ac)27]-Histone H3 (21-43)-GGK(Biotin)

Sequence One Letter Code: ATKAAR-K(Ac)-SAPATGGVKKPHRYRP-GGK(Biotin)

Sequence Three Letter Code: H-Ala-Thr-Lys-Ala-Ala-Arg-Lys(Ac)-Ser-Ala-Pro-Ala-Thr-Gly-Gly-Val-Lys-Lys-Pro-His-Arg-Tyr-Arg-Pro-Gly-Gly-Lys(Biotin)-OH

Molecular Weight: 2959.6

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 21–43 and is site-specifically acetylated at lysine 27, a hallmark of transcriptionally active chromatin and enhancer regions. A C-terminal glycine–glycine linker followed by a biotinylated lysine facilitates immobilization and pull-down applications. Acetylation at H3K27 regulates chromatin accessibility and gene expression by recruiting bromodomain-containing reader proteins and chromatin remodeling complexes. The peptide is suitable for histone acetyltransferase assays, interaction studies, and antibody validation. It provides a defined biochemical tool for dissecting transcriptional regulation mechanisms and epigenetic control of gene activation.

Current Research: Epigenetic regulation plays a central role in controlling gene expression, cellular differentiation, and genome organization. One of the most important mechanisms underlying epigenetic regulation is the post-translational modification (PTM) of histone proteins, which influences chromatin accessibility and transcriptional activity. Among these modifications, acetylation of lysine 27 on histone H3 (H3K27ac) is widely recognized as a hallmark of active chromatin and enhancer regions. Synthetic peptides containing defined histone modifications have become essential tools for studying how these epigenetic marks regulate chromatin-associated processes. The biotinylated H3 (21–43) peptide acetylated at lysine 27 provides a precisely defined reagent for investigating histone acetylation, chromatin interactions, and transcriptional regulation. Histone H3 and the Role of Epigenetic Modifications Histone H3 is one of the core proteins that form the nucleosome, the fundamental structural unit of chromatin. Within the nucleosome, DNA wraps around a histone octamer composed of two copies each of histones H2A, H2B, H3, and H4. Extending outward from this structure are the N-terminal and internal histone tail regions, which serve as platforms for regulatory modifications. These modifications—including acetylation, methylation, phosphorylation, and ubiquitination—collectively form part of the “histone code,” a system of molecular signals that guide chromatin structure and transcriptional activity. By influencing interactions between histones, DNA, and chromatin-associated proteins, histone modifications help regulate the accessibility of genomic regions to transcriptional machinery. The peptide corresponding to histone H3 residues 21–43 encompasses an important regulatory region of the H3 protein that contains lysine 27, a residue frequently modified during transcriptional activation. Functional Importance of H3K27 Acetylation Acetylation at lysine 27 of histone H3 (H3K27ac) is a key epigenetic marker associated with active promoters and enhancers. In contrast to methylation at the same residue—which is commonly linked to transcriptional repression—acetylation promotes a chromatin environment favorable for gene expression. Acetylation neutralizes the positive charge of lysine residues, reducing electrostatic interactions between histones and negatively charged DNA. This change results in a more relaxed chromatin structure, allowing transcription factors and RNA polymerase complexes greater access to DNA. In addition to altering chromatin structure directly, H3K27 acetylation acts as a recruitment signal for bromodomain-containing reader proteins. These proteins recognize acetylated lysine residues and help recruit transcriptional regulators, chromatin remodeling complexes, and coactivator proteins that facilitate gene activation. Structural Design of the Synthetic Peptide The synthetic H3 (21–43) K27ac peptide is designed to reproduce a specific segment of histone H3 while incorporating features that enable efficient experimental use. The peptide sequence spans residues 21 through 43 of histone H3, ensuring that lysine 27 appears within its native sequence context. At this position, the lysine residue is site-specifically acetylated, precisely replicating the epigenetic modification found in transcriptionally active chromatin. The peptide also includes a C-terminal glycine–glycine linker followed by a biotinylated lysine residue. This structural addition allows the peptide to be immobilized on streptavidin-coated surfaces while maintaining accessibility of the histone sequence for binding interactions. The flexible glycine spacer helps minimize steric hindrance between the histone sequence and the immobilization surface, preserving the biochemical integrity of the modified region. Applications in Chromatin Interaction Studies Biotinylated histone peptides are widely used in pull-down assays and protein interaction studies. In these experiments, the peptide is immobilized using the strong affinity between biotin and streptavidin. Nuclear extracts or purified proteins can then be incubated with the immobilized peptide to identify factors that specifically recognize the H3K27ac modification. Such experiments are particularly useful for studying bromodomain-containing proteins, which selectively bind acetylated lysine residues on histones. These interactions play a critical role in recruiting transcriptional regulators and chromatin remodeling complexes to active genomic regions. By providing a well-defined substrate, the H3K27ac peptide allows researchers to examine how chromatin reader proteins interpret histone acetylation signals. Utility in Histone Acetyltransferase Assays The peptide also serves as a useful substrate for histone acetyltransferase (HAT) assays. Histone acetyltransferases are enzymes responsible for adding acetyl groups to lysine residues on histones, thereby regulating transcriptional activity. Although the peptide already contains acetylation at lysine 27, it can still be used in comparative assays to examine enzyme recognition of histone sequences or to evaluate the specificity of acetyltransferase activity toward particular histone regions. These assays help clarify how histone-modifying enzymes contribute to dynamic epigenetic regulation. Validation of Modification-Specific Antibodies Another important use of modified histone peptides is antibody validation. Antibodies designed to recognize histone modifications must distinguish between modified and unmodified residues with high specificity. Synthetic peptides such as H3K27ac provide well-defined standards for assessing antibody performance in assays including ELISA, western blotting, and chromatin immunoprecipitation (ChIP). By comparing antibody binding to modified and control peptides, researchers can confirm that antibodies selectively recognize the intended epigenetic mark. Reliable antibody validation is essential for accurate interpretation of chromatin-based experiments. Supporting Research on Epigenetic Control of Gene Activation Because H3K27ac is strongly associated with active regulatory elements, tools that model this modification are valuable for studying transcriptional regulation and enhancer activity. Synthetic peptides enable detailed biochemical investigations of how specific epigenetic marks recruit regulatory complexes and influence chromatin accessibility. By providing a defined and reproducible substrate, the biotinylated H3 (21–43) K27ac peptide supports studies aimed at understanding the molecular mechanisms underlying gene activation, chromatin remodeling, and epigenetic signaling pathways. Conclusion The biotinylated H3K27ac peptide corresponding to histone H3 residues 21–43 offers a powerful experimental reagent for investigating epigenetic regulation. By incorporating site-specific acetylation at lysine 27 along with a biotin capture tag, the peptide enables efficient analysis of histone–protein interactions, chromatin reader recognition, and transcription-associated signaling mechanisms. Its applications span histone acetyltransferase assays, pull-down experiments, antibody validation, and studies of enhancer-associated chromatin activity. As research continues to uncover the complex networks governing gene expression, well-defined histone peptides like H3K27ac remain indispensable tools for exploring the biochemical foundations of epigenetic control.