Di-Methyl-Histone H2B (Lys5) Antibody

Basic Research Questions

• What is Di-Methyl-Histone H2B (Lys5) and why is it important in epigenetic research?

Di-Methyl-Histone H2B (Lys5) refers to the post-translational modification where two methyl groups are attached to the lysine residue at position 5 of histone H2B. This modification is part of the histone code that regulates chromatin structure and gene expression.

Histone H2B is one of the four core histones (H2A, H2B, H3, and H4) that form the nucleosome, the basic structural unit of chromatin. The nucleosome consists of approximately 146 base pairs of DNA wrapped around a histone octamer . Methylation at Lys5 of histone H2B contributes to the regulation of chromatin structure and function, similar to how methylation of histone H3 affects gene expression patterns .

Research methodology to study this modification typically involves antibody-based detection in combination with techniques such as Western blotting, chromatin immunoprecipitation (ChIP), and mass spectrometry-based quantification approaches.

• How specific is the Di-Methyl-Histone H2B (Lys5) Antibody compared to antibodies targeting other histone modifications?

Di-Methyl-Histone H2B (Lys5) antibodies vary in their specificity depending on the manufacturer and production method. High-quality antibodies should specifically detect endogenous histone H2B when di-methylated at Lys5 with minimal cross-reactivity.

Experimental data shows that some antibodies marketed as specific for H2B Lys5 di-methylation may display cross-reactivity with other modifications. For example, in pre-clearing experiments using peptide arrays, researchers have observed that some antibodies targeting specific methylation sites can recognize multiple methylation patterns .

Cross-reactivity testing results for a typical Di-Methyl-Histone H2B (Lys5) antibody:

To validate antibody specificity, researchers should perform pre-clearing experiments using peptide competition assays where unmodified and specifically modified peptides are used to compete for antibody binding .

• What are the primary applications for Di-Methyl-Histone H2B (Lys5) Antibody in research?

The primary applications for Di-Methyl-Histone H2B (Lys5) Antibody include:

• Western Blotting (WB): The most common application, used to detect and quantify the presence of di-methylated H2B Lys5 in protein samples. The expected molecular weight on SDS-PAGE is approximately 14 kDa .

• Immunoprecipitation (IP): Used to isolate di-methylated H2B Lys5 and associated proteins or DNA sequences.

• Chromatin Immunoprecipitation (ChIP): While less common than for H3 modifications, ChIP can be used to identify genomic regions associated with H2B Lys5 di-methylation.

• Immunofluorescence (IF): Used to visualize the nuclear localization and distribution of di-methylated H2B Lys5 in cells.

For optimal results in Western blotting, researchers typically use dilutions between 1:1000 and 1:2000 of the antibody . For ChIP applications, protocols often recommend using 10 μl of antibody with approximately 10 μg of chromatin (equivalent to about 4 × 10^6 cells) per immunoprecipitation .

• What species reactivity is expected with commercially available Di-Methyl-Histone H2B (Lys5) Antibodies?

Commercially available Di-Methyl-Histone H2B (Lys5) Antibodies typically show reactivity against several mammalian species due to the high conservation of histone proteins. Based on the product specifications, the following species reactivity is common:

Most commercial antibodies are raised against synthetic peptides corresponding to residues surrounding Lys5 of human histone H2B . The high degree of sequence conservation in the N-terminal tail of histone H2B across mammalian species explains the broad cross-species reactivity . Researchers should validate the antibody in their specific species of interest, especially when working with non-mammalian models.

• What is the difference between mono-methylation and di-methylation at Lys5 of histone H2B?

Mono-methylation (Me1) and di-methylation (Me2) at Lys5 of histone H2B represent different degrees of methylation at the same lysine residue, with distinct biological functions and recognition by different effector proteins:

Researchers studying these modifications must use antibodies specifically validated for the degree of methylation (mono-, di-, or tri-) they are investigating, as cross-reactivity between these states can occur . Mass spectrometry-based approaches can provide definitive identification of the methylation state when antibody specificity is a concern .

Advanced Research Questions

• How does Di-Methyl-Histone H2B (Lys5) interact with other histone modifications in the context of the histone code?

Di-Methyl-Histone H2B (Lys5) functions within a complex network of histone modifications that collectively form the histone code. Research suggests several key interactions:

• Cross-talk with H2B ubiquitination: Studies have demonstrated a relationship between H2B methylation and H2B ubiquitination at Lys120. This interaction forms part of a regulatory mechanism that affects downstream methylation events on histone H3 .

• Relationship with H3K79 methylation: Research using the U937 human leukemia cell line and its derivatives has revealed a potential "cross-talk" between H2B modifications and H3K79 methylation mediated by the hDot1L methyltransferase pathway .

• Coordination with acetylation marks: H2B Lys5 can be either methylated or acetylated, and these modifications are mutually exclusive at the same residue. The balance between these modifications may regulate different cellular processes .

To study these interactions, researchers can employ:

• Sequential ChIP (Re-ChIP) to identify genomic regions with co-occurrence of modifications

• Mass spectrometry-based approaches to quantify multiple modifications simultaneously

• Genetic studies using methyltransferase mutants to assess functional relationships

Researchers investigating the U937 cell line observed an unexpected inhibitory effect of histone H3K79 methylation on histone H2B ubiquitination, suggesting complex regulatory relationships between different histone modifications .

• What are the optimal conditions for using Di-Methyl-Histone H2B (Lys5) Antibody in chromatin immunoprecipitation (ChIP) experiments?

For optimal chromatin immunoprecipitation (ChIP) experiments using Di-Methyl-Histone H2B (Lys5) Antibody, researchers should follow these methodological guidelines:

• Chromatin preparation:

  • Use formaldehyde (1% final concentration, 10 minutes at room temperature) for cross-linking

  • Sonicate chromatin to generate fragments of 200-600 bp

  • Verify fragmentation by agarose gel electrophoresis

  • Use approximately 10 μg of chromatin per immunoprecipitation

• Antibody amount and incubation:

  • Use 10 μl of antibody per IP reaction for 10 μg of chromatin (approximately 4 × 10^6 cells)

  • Incubate overnight at 4°C with rotation

  • Include appropriate controls (IgG negative control, H3 positive control)

• Washing and elution:

  • Perform stringent washes to remove non-specific binding

  • Elute bound material and reverse cross-links (typically at 65°C overnight)

  • Purify DNA for downstream analysis

• Validation:

  • Perform qPCR on positive and negative control regions

  • Include input controls for normalization

  • Consider performing validation using mass spectrometry to confirm antibody specificity

The low abundance of some histone modifications makes antibody specificity particularly important in ChIP experiments. Researchers should validate their antibody using peptide competition assays or testing on cells with known mutation or depletion of the target modification .

• How can mass spectrometry be used to validate the specificity of Di-Methyl-Histone H2B (Lys5) Antibody?

Mass spectrometry (MS) provides a powerful approach to validate antibody specificity for histone modifications, including Di-Methyl-Histone H2B (Lys5). The following methodology can be implemented:

• Sample preparation for MS validation:

  • Purify core histones from 10 million cells using acid-precipitation methods

  • Separate histones into H2A, H2B, H3, and H4 using reversed-phase HPLC or SDS-PAGE

  • Digest purified histones with trypsin or other suitable proteases

• LC-MS/MS-MRM (Multiple Reaction Monitoring) approach:

  • Develop specific MRM transitions for the peptides containing unmodified, mono-methylated, and di-methylated Lys5 of H2B

  • Use synthetic peptide standards to optimize LC-MS/MS conditions

  • Monitor multiple transitions per peptide for increased specificity

• Quantitative assessment:

  • Compare signal intensities between modified and unmodified peptides

  • Use heavy isotope-labeled internal standards for absolute quantification

  • Calculate the specificity ratio by comparing antibody pull-down efficiency for target vs. off-target modifications

Example MRM parameters for H2B Lys5 methylation analysis:

This approach can reveal cross-reactivity that might not be apparent in antibody-based methods alone, as demonstrated in studies that identified unexpected cross-reactivity of some histone modification antibodies .

• What is the role of H2B Lys5 di-methylation in gene expression regulation?

H2B Lys5 di-methylation plays several roles in gene expression regulation, though it has been less extensively studied than some H3 modifications. Current research indicates:

• Association with transcriptional states: While mono-methylation of lysine 5 appears to occur at active promoters downstream of transcription start sites , di-methylation may be associated with different transcriptional contexts or regulatory mechanisms.

• Involvement in heat-shock response: Similar to other histone H2B modifications, changes in methylation patterns at Lys5 may be involved in cellular responses to stress conditions, including heat shock .

• Coordination with the histone code: Di-methylation at Lys5 functions within the broader context of histone modifications that collectively regulate chromatin structure and accessibility.

• Potential role in autoimmune responses: Research using peptide microarrays has shown that epitopes containing various H2B modifications, including those around Lys5, may be important in breaking tolerance to H2B and contributing to autoantibody pathogenesis in systemic lupus erythematosus (SLE) .

Experimental approaches to study this function include:

• ChIP-seq to map genomic localization of this modification

• Correlation with transcriptome data to assess association with gene expression

• Genetic studies using methyltransferase knockdowns or inhibitors

• Analysis of reader proteins that specifically recognize this modification

Research has demonstrated that N-terminal reactivity to a minimum sequence Pro1-Lys5, as well as reactivity to epitopes surrounding methylated lysine residues, may have implications in autoimmune conditions like interferon-α-driven SLE .

• How do you troubleshoot cross-reactivity issues with Di-Methyl-Histone H2B (Lys5) Antibody?

Cross-reactivity is a common challenge when working with histone modification antibodies. To troubleshoot cross-reactivity issues with Di-Methyl-Histone H2B (Lys5) Antibody, follow these methodological approaches:

• Peptide competition assays:

  • Pre-incubate the antibody with increasing concentrations of the target peptide (containing di-methylated Lys5)

  • In parallel, pre-incubate with potential cross-reacting peptides (mono-methylated, unmodified, or other modified sites)

  • Compare signal reduction to identify specific vs. non-specific binding

• Pre-clearing experiments:

  • Immobilize different modified peptides on beads or columns

  • Pass the antibody through these columns to remove cross-reactive antibody populations

  • Test the pre-cleared antibody for improved specificity

• Western blot validation panel:

  • Prepare samples from cells treated with specific methyltransferase inhibitors

  • Include recombinant or synthetic histone standards with defined modifications

  • Compare signal patterns to identify non-specific binding

• Dot blot specificity testing:

  • Spot modified and unmodified peptides at known concentrations

  • Probe with the antibody to determine relative affinity

  • Create a cross-reactivity profile

Example of pre-clearing results from a study addressing cross-reactivity:

Researchers have found that some commercially available antibodies designed to recognize H3K27me2 show cross-reactivity with H2B when di-methylated on Lys5 , demonstrating the importance of validation.

Methodological Questions

• What are the recommended protocols for sample preparation when using Di-Methyl-Histone H2B (Lys5) Antibody?

Proper sample preparation is critical for successful detection of Di-Methyl-Histone H2B (Lys5). The following protocol ensures optimal results:

• Cell/tissue harvesting and histone extraction:

  • Harvest cells at 70-80% confluence (approximately 10^7 cells per preparation)

  • Wash cells twice with ice-cold PBS containing protease inhibitors

  • Extract histones using the acid extraction method:
    a. Lyse cells in Triton Extraction Buffer (PBS with 0.5% Triton X-100, 2mM PMSF, 0.02% NaN₃)
    b. Resuspend nuclei in 0.2N HCl
    c. Extract overnight at 4°C
    d. Centrifuge and collect supernatant containing histones
    e. Neutralize with 1/10 volume of 2M NaOH

• Histone purification:

  • Further purify extracted histones using reversed-phase HPLC

  • Alternatively, separate histones by SDS-PAGE and excise the appropriate band

  • For core histone purification from 10 million cells, approximately 200 μg can be obtained

• Sample preparation for Western blotting:

  • Resuspend histones in SDS sample buffer

  • Heat at 95°C for 5 minutes

  • Load 2-5 μg of histone preparation per lane

  • Include methyltransferase inhibitor-treated samples as controls

  • Use fresh β-mercaptoethanol in sample buffer to prevent oxidation artifacts

• Storage considerations:

  • Store extracted histones at -80°C for long-term storage

  • Avoid repeated freeze-thaw cycles

  • For the antibody, store at -20°C as indicated in product specifications

When analyzing modifications with mass spectrometry, an additional step of propionylation of unmodified and mono-methylated lysines is recommended to improve peptide retention and detection sensitivity .

• How can you quantitatively assess histone H2B Lys5 di-methylation levels across different cell types?

Quantitative assessment of histone H2B Lys5 di-methylation across different cell types requires systematic approaches that combine multiple techniques:

• LC-MS/MS-MRM (Multiple Reaction Monitoring) approach:

  • Develop specific transitions for peptides containing H2B Lys5-Me2

  • Use synthetic peptide standards for absolute quantification

  • Calculate modification stoichiometry (percentage of histone molecules bearing the modification)

  • This approach allows simultaneous quantification of multiple modifications

  • For example, one study quantified nearly 20 modification sites including acetylation, propionylation, methylation, and ubiquitination within 2 hours for two samples to be compared

• Western blot quantification:

  • Use purified recombinant histones with known modifications as standards

  • Generate standard curves for accurate quantification

  • Normalize to total H2B levels using pan-H2B antibodies

  • Employ digital image analysis software for densitometry

• ELISA-based methods:

  • Develop sandwich ELISA with one antibody capturing total H2B and another specific for the modification

  • Use recombinant standards with defined modifications

  • Create a standard curve for quantification across samples

• Fluorescence polarization (FP) assays:

  • Develop assays similar to those used for methyl-histone binding studies

  • Measure the interaction between fluorescently labeled peptides and specific reader proteins

  • Use this approach to indirectly quantify modification levels

When comparing modification levels across different cell types, researchers should:

• Standardize cell harvesting conditions (confluence, passage number, etc.)

• Process all samples in parallel to minimize technical variation

• Use multiple technical and biological replicates

• Consider normalization to other histone modifications or total histone levels

The mass spectrometry-based approach is particularly powerful as it can simultaneously measure multiple modifications, allowing researchers to detect relationships between different marks, such as the cross-talk between H2B modifications and H3K79 methylation .

• What controls should be included when using Di-Methyl-Histone H2B (Lys5) Antibody in experiments?

Proper experimental controls are essential when using Di-Methyl-Histone H2B (Lys5) Antibody to ensure valid and interpretable results:

• Antibody validation controls:

  • Peptide competition assay: Pre-incubate antibody with excess of the specific peptide containing H2B Lys5-Me2 to demonstrate specificity

  • Positive control samples: Include cell lines or tissues known to express high levels of the modification

  • Negative control samples: Use samples from cells treated with methyltransferase inhibitors or cells with genetic knockout of relevant methyltransferases

  • Cross-reactivity controls: Test antibody against peptide arrays containing various histone modifications to assess specificity

• Western blot controls:

  • Loading control: Probe with pan-histone H2B antibody to normalize for total H2B levels

  • Molecular weight marker: Confirm the expected 14 kDa band size for H2B

  • Recombinant standards: Include purified recombinant histones with defined modifications

  • Secondary antibody only: Confirm absence of non-specific binding

• ChIP experiment controls:

  • Input sample: Unprecipitated chromatin to normalize for starting material

  • IgG control: Non-specific antibody of the same isotype to assess background

  • Positive control regions: Genomic regions known to be enriched for the modification

  • Negative control regions: Genomic regions known to lack the modification

  • Technical replicates: Multiple immunoprecipitations from the same chromatin preparation

• Immunofluorescence controls:

  • Secondary antibody only: Assess background fluorescence

  • Peptide competition: Pre-incubate with specific peptide to demonstrate specificity

  • DAPI staining: Confirm nuclear localization of the signal

When conducting fluorescence polarization binding assays similar to those for methyl-histone binding studies, a positive control protein (like HP1 for H3K9me) should be included to validate the assay system .

• How does the choice between polyclonal and monoclonal Di-Methyl-Histone H2B (Lys5) Antibodies affect experimental outcomes?

The choice between polyclonal and monoclonal Di-Methyl-Histone H2B (Lys5) Antibodies significantly impacts experimental design, data interpretation, and results:

Methodological considerations for experimental design:

• For initial screening or when signal strength is a priority, polyclonal antibodies may be preferable

• For genome-wide studies (ChIP-seq) or when precise epitope recognition is critical, monoclonal antibodies offer advantages

• When using polyclonal antibodies, more rigorous validation is necessary:

  • Pre-clear with potential cross-reacting peptides

  • Perform peptide competition assays

  • Include appropriate controls for non-specific binding

Researchers should note that some commercial antibodies marketed as specific for H2B Lys5-Me2 demonstrate cross-reactivity with other modifications, such as the observation that some H3K27me2 antibodies cross-react with H2B when di-methylated on Lys5 .

• What are the best storage and handling practices for maintaining Di-Methyl-Histone H2B (Lys5) Antibody activity?

Proper storage and handling of Di-Methyl-Histone H2B (Lys5) Antibody is essential for maintaining its activity and specificity over time. Follow these methodological guidelines:

• Storage temperature:

  • Store antibody at -20°C for long-term storage, as indicated in product specifications

  • Avoid storing at 4°C for extended periods

  • Avoid repeated freeze-thaw cycles by preparing single-use aliquots

• Buffer conditions:

  • Most commercial antibodies are formulated with 50% glycerol and 0.02% sodium azide as preservatives

  • Maintain sterile conditions when handling

  • Do not dilute the stock antibody unless preparing working aliquots

• Aliquoting practice:

  • Upon receipt, prepare small single-use aliquots (10-20 μl)

  • Use sterile microcentrifuge tubes

  • Quick-freeze aliquots in liquid nitrogen before transferring to -20°C

  • Label tubes with antibody name, lot number, concentration, and date

• Handling during experiments:

  • Thaw aliquots on ice

  • Centrifuge briefly before opening to collect contents

  • Use clean pipette tips for each handling

  • Return to ice immediately after use

  • Never refreeze thawed antibodies

• Working dilution preparation:

  • Prepare fresh working dilutions for each experiment

  • Use high-quality blocking reagents (BSA or non-fat dry milk)

  • For Western blotting, typical working dilutions range from 1:1000 to 1:2000

  • For immunofluorescence, dilutions may range from 1:800 to 1:3200

• Stability considerations:

  • Expect approximately 12 months of stability when stored properly

  • Monitor for signs of decreased activity over time

  • If reduced activity is observed, validate with positive controls

  • Record lot-to-lot variation when purchasing new antibodies

Following these practices will help ensure consistent and reliable results when using Di-Methyl-Histone H2B (Lys5) Antibody in research applications.