[Lys(Me1)9]-Histone H3 (1-21)

Product Name: [Lys(Me1)9]-Histone H3 (1-21)

Sequence One Letter Code: ARTKQTAR-K(Me1)-STGGKAPRKQLA

Sequence Three Letter Code: H-Ala-Arg-Thr-Lys-Gln-Thr-Ala-Arg-Lys(Me1)-Ser-Thr-Gly-Gly-Lys-Ala-Pro-Arg-Lys-Gln-Leu-Ala-OH

Molecular Weight: 2268.8

Purity: 95%

Form: Lyophilized

Storage Conditions: - 20 °C

Research Area: Cancer Disease Research

Source / Species: human

Conjugation: Unconjugated

Code Nacres: NA.26

Application: [Lys(Me1)9]-Histone H3 (1–21) is a synthetic peptide corresponding to the N-terminal 21 amino acids of histone H3, monomethylated at lysine 9. H3K9 monomethylation is commonly enriched near transcription start sites and is associated with active or poised chromatin states, distinct from the repressive trimethylated form. This modification plays a role in regulating chromatin accessibility and recruitment of histone-binding proteins. The peptide has been used as a control substrate in time-resolved FRET assays for identifying inhibitors of histone lysine demethylases and for evaluating demethylase specificity. It supports epigenetic enzyme profiling, assay development, and studies of chromatin modification dynamics in transcriptional regulation research.

Current Research: [Lys(Me1)9]-Histone H3 (1–21) is a synthetic peptide encompassing the first 21 amino acids of histone H3 and carrying a site-specific monomethylation at lysine 9 (H3K9me1). The H3 N-terminal tail is a highly dynamic regulatory domain that protrudes from the nucleosome core and undergoes extensive post-translational modifications (PTMs) governing chromatin accessibility and transcriptional control. By isolating this defined modification within a minimal tail fragment, the peptide provides a controlled substrate for mechanistic and enzymatic studies of histone methylation biology. H3K9 methylation exists in mono-, di-, and trimethylated states, each associated with distinct functional outcomes. While H3K9me3 is strongly linked to constitutive heterochromatin and transcriptional repression, H3K9me1 is more frequently enriched at transcription start sites and enhancer regions associated with active or poised chromatin. Genome-wide profiling studies indicate that H3K9me1 can function as an intermediate state in chromatin remodeling and may participate in dynamic transitions between activation and repression. Enzymatically, H3K9 methylation is catalyzed by histone lysine methyltransferases (KMTs) such as G9a/GLP and SET domain–containing proteins. Demethylation is mediated by histone lysine demethylases (KDMs), including members of the KDM1 (LSD1) and KDM4 families, which exhibit substrate specificity depending on methylation state. The [Lys(Me1)9]-H3 (1–21) peptide is widely used to assess demethylase activity and to define enzyme selectivity for mono- versus di- or trimethylated substrates. In assay development, this peptide serves as a well-characterized control substrate in fluorescence-based and time-resolved FRET (TR-FRET) assays designed to identify inhibitors of histone demethylases. In such assays, the methylated peptide is recognized by a methyl-lysine–specific antibody, and demethylation reduces signal intensity in a quantitative manner. The defined monomethylated state allows discrimination of demethylase specificity and supports kinetic characterization of catalytic efficiency. These platforms are frequently used in high-throughput screening for epigenetic modulators. Beyond enzyme profiling, [Lys(Me1)9]-Histone H3 (1–21) supports studies of modification-dependent protein recruitment. H3K9 methylation can influence binding of chromodomain-containing proteins and other histone “reader” domains. Although higher methylation states are more strongly associated with heterochromatin protein 1 (HP1) binding, monomethylation may influence chromatin accessibility and serve as a precursor to further modification. Comparative binding assays using mono-, di-, and trimethylated peptides help delineate reader domain specificity and modification thresholds. The peptide is also useful for antibody validation and epitope specificity testing. Because subtle differences in methylation state significantly impact biological interpretation, confirming that antibodies discriminate between H3K9me1, H3K9me2, and H3K9me3 is essential. Defined synthetic peptides provide critical controls for dot blot, ELISA, and immunoassay calibration. In transcriptional regulation research, H3K9me1 is increasingly recognized as part of dynamic chromatin modification cycles. It may participate in transcriptional priming, enhancer activation, and chromatin remodeling events during development and differentiation. The synthetic peptide enables controlled biochemical analysis of these modification-dependent mechanisms outside the complexity of full nucleosomal context. Overall, [Lys(Me1)9]-Histone H3 (1–21) is a precise and experimentally tractable reagent for studying H3K9 monomethylation biology. Its applications span demethylase inhibitor screening, enzyme specificity profiling, reader domain interaction analysis, and assay validation. By supporting detailed investigation of methylation-state–dependent chromatin regulation, this peptide contributes to broader understanding of epigenetic dynamics in transcriptional control.