Histone H3 (1-25), amide

Product Name: Histone H3 (1-25), amide

Sequence One Letter Code: ARTKQTARKSTGGKAPRKQLATKAA-NH2

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-Thr-Lys-Ala-Ala-NH2

Chemical Formula:C110H202N42O32

Molecular Weight: 2625.2

Purity: 95%

Form: Lyophilized

Storage Conditions: - 20 °C

Research Area: peptide substrate

Source / Species: human

Conjugation: Unconjugated

Code Nacres: NA.26

Application: This peptide represents the N-terminal 25 amino acids of histone H3 and is amidated at the C-terminus to enhance stability and mimic the native histone tail environment. The H3 N-terminal region is a major regulatory platform for post-translational modifications such as methylation, acetylation, and phosphorylation, which collectively influence chromatin structure and transcriptional activity. Because many chromatin-modifying enzymes recognize this region, the peptide is commonly used as a substrate or reference sequence in biochemical assays. It supports studies of histone modification enzymes, chromatin remodeling complexes, and protein–histone binding interactions. This peptide is widely applied in epigenetics and transcription research investigating how histone modifications regulate gene expression and chromatin accessibility.

Current Research: Chromatin structure plays a fundamental role in controlling gene expression in eukaryotic cells. At the core of this regulatory system are histone proteins, which organize DNA into nucleosomes and provide a platform for a wide range of post-translational modifications (PTMs). Among these histones, histone H3 is particularly important because its N-terminal tail contains multiple residues that undergo regulatory modifications influencing transcriptional activity and chromatin accessibility. The Histone H3 (1–25) amide peptide, representing the first 25 amino acids of the H3 N-terminal tail with a C-terminal amidation, is widely used as a model substrate for studying chromatin regulation and histone-modifying enzymes. The Histone H3 N-Terminal Tail Histone H3 is one of the four core histone proteins—H2A, H2B, H3, and H4—that assemble into nucleosomes, the basic structural units of chromatin. DNA wraps around a histone octamer composed of two copies of each core histone, forming a compact structure that helps organize and protect genomic DNA. Extending outward from the nucleosome core are histone tails, flexible regions that are accessible to chromatin-modifying enzymes. The N-terminal tail of histone H3 is particularly rich in lysine, arginine, and serine residues that serve as sites for regulatory modifications. These modifications include lysine acetylation, lysine and arginine methylation, and serine phosphorylation, among others. The first 25 amino acids of histone H3 encompass several well-characterized modification sites, including H3K4, H3K9, H3K14, and H3K23, which are frequently studied in the context of transcriptional regulation and chromatin dynamics. Because of its importance as a regulatory hub, this region is widely used in biochemical and structural studies examining chromatin signaling pathways. Functional Importance of Histone Modifications Post-translational modifications on histone tails regulate chromatin structure through two main mechanisms. First, they can alter the electrostatic interactions between histones and DNA, affecting the physical accessibility of chromatin. Second, these modifications create binding sites for specialized reader proteins, which recruit chromatin remodeling complexes and transcriptional regulators. For example, acetylation of lysine residues is commonly associated with transcriptionally active chromatin because it neutralizes the positive charge of lysine, weakening histone–DNA interactions and promoting a more open chromatin conformation. In contrast, methylation marks can either activate or repress transcription depending on the specific residue modified and the number of methyl groups added. The N-terminal region of histone H3 serves as a central platform where these regulatory signals are integrated, making it a critical focus in studies of epigenetic control. Design and Properties of the H3 (1–25) Amide Peptide The H3 (1–25) peptide replicates the sequence of the natural histone H3 N-terminal tail, providing a simplified model for studying histone interactions outside the context of full nucleosomes. The peptide includes a C-terminal amidation, which improves stability and more closely resembles the chemical environment of the native histone tail within chromatin. Because the peptide retains the key residues targeted by chromatin-modifying enzymes, it can serve as a convenient substrate for biochemical assays designed to evaluate enzyme activity or protein–histone interactions. Applications in Enzyme Activity Assays One of the primary uses of the H3 (1–25) amide peptide is as a substrate for histone-modifying enzymes. Enzymes such as histone acetyltransferases (HATs), histone methyltransferases (HMTs), and kinases recognize residues within the histone H3 N-terminal region and catalyze specific modifications. Using a defined peptide substrate allows researchers to examine enzyme specificity, catalytic efficiency, and regulatory mechanisms in controlled in vitro assays. Such experiments help clarify how different chromatin-modifying enzymes recognize histone sequences and how modification patterns are established across the genome. This approach is particularly valuable for screening inhibitors or modulators that influence histone modification pathways, which are increasingly relevant in epigenetic drug discovery. Investigating Chromatin-Associated Protein Interactions In addition to enzyme studies, the H3 (1–25) peptide is commonly used to explore protein–histone binding interactions. Many chromatin-associated proteins contain specialized domains that recognize specific histone sequences or modification states. For example, chromodomains, PHD fingers, and bromodomains bind to modified histone residues and help recruit transcriptional regulators or chromatin remodeling complexes. By using the H3 (1–25) peptide in binding assays, researchers can examine how these proteins recognize histone tails and interpret epigenetic signals. These experiments provide insight into how combinations of histone modifications contribute to the “histone code,” a regulatory framework in which multiple modifications collectively influence chromatin function. Relevance to Epigenetics and Gene Regulation Because histone H3 modifications play central roles in controlling gene expression, the H3 (1–25) peptide is widely applied in epigenetics research. Studies using this peptide help uncover how chromatin structure is dynamically regulated during processes such as cellular differentiation, development, and environmental response. Researchers also use the peptide in assays designed to evaluate chromatin remodeling complexes, which reposition or restructure nucleosomes to regulate DNA accessibility. Understanding how histone tails interact with these complexes provides important insight into the mechanisms that control transcriptional activation and repression. Supporting Advances in Chromatin Biology The Histone H3 (1–25) amide peptide offers a practical and versatile model for studying the molecular mechanisms that govern chromatin regulation. By reproducing the key sequence of the histone H3 N-terminal tail, the peptide enables controlled investigation of histone modification enzymes, chromatin-binding proteins, and epigenetic signaling pathways. As research continues to uncover the complexity of chromatin-based regulation, defined histone peptides such as H3 (1–25) remain valuable tools for exploring how histone modifications shape gene expression and influence cellular function.