Recombinant Human MBD4 Protein: Handling & Usage Protocol

Recombinant Human MBD4 Protein is a research-grade recombinant protein designed for use in studies of DNA mismatch repair, methyl-CpG binding, and epigenetic regulation.

Product Name

Recombinant Human MBD4 Protein

SKU

rp377562

Protein Function

Methyl-CpG binding and DNA glycosylase activity involved in DNA repair

Application

Epigenetics research, DNA repair assays, biochemical studies

Storage Recommendation

Avoid repeated freeze-thaw cycles; store at -80°C for long-term

Species

Human (Homo sapiens)

Background: MBD4 Biology and Research Relevance

Methyl-CpG Binding Domain Protein 4 (MBD4) is a nuclear protein that plays a dual role in genome stability. It contains an N-terminal methyl-CpG binding domain (MBD) that selectively recognizes symmetrically methylated CpG dinucleotides, and a C-terminal thymine DNA glycosylase (TDG) domain responsible for base excision repair (BER).

MBD4 specifically removes thymine and uracil mismatched opposite guanine at methylated CpG sites, thereby suppressing the mutagenic consequences of spontaneous cytosine deamination. Loss-of-function mutations in MBD4 have been associated with colorectal cancer and elevated C→T transition rates at CpG sites.

Recombinant Human MBD4 Protein is a valuable tool for researchers investigating epigenetic regulation, DNA methylation-coupled repair mechanisms, and cancer biology.

Reagent Preparation and Reconstitution

Upon receipt, briefly centrifuge the vial at low speed (e.g., 1,000 × g for 30 seconds) to collect any residual material from the tube walls and cap before opening.

Reconstitution: Reconstitute lyophilized Recombinant Human MBD4 Protein in sterile, deionized water or an appropriate buffer (e.g., PBS containing 0.1% BSA or 50 mM Tris-HCl, pH 7.5, with 150 mM NaCl and 10% glycerol). Add the reconstitution buffer slowly and gently swirl the vial; do not vortex, as this may cause protein denaturation or aggregation.

Working concentration: Determine the optimal working concentration empirically for each specific assay. Prepare working aliquots to minimize the number of freeze-thaw cycles.

Note: Specific reconstitution volumes and buffer compositions should be verified against the product datasheet supplied with SKU rp377562.

Storage and Handling Guidelines

Short-term storage (up to 1 week): Store reconstituted protein at 4°C. Keep the vial tightly sealed to prevent contamination and evaporation.

Long-term storage: Aliquot the reconstituted protein into single-use volumes and store at -80°C. This minimizes degradation due to repeated freeze-thaw cycles, which can significantly reduce protein activity.

Freeze-thaw cycles: Limit to a maximum of 2–3 cycles. Each additional freeze-thaw event may result in loss of biological activity and increased protein aggregation.

Avoid: Prolonged exposure to room temperature, repeated freeze-thaw cycles, and storage in frost-free freezers (which undergo temperature fluctuations).

Note: Always consult the product-specific datasheet for validated storage conditions for SKU rp377562.

Recommended Applications and Assay Protocol

Recombinant Human MBD4 Protein (rp377562) is suitable for the following research applications:

• DNA Glycosylase Activity Assay: Use MBD4 to assess base excision of thymine or uracil from G:T or G:U mispairs at CpG sites in methylated double-stranded DNA substrates. Typical assay formats include radioactive or fluorescence-based oligonucleotide cleavage assays.
• Electrophoretic Mobility Shift Assay (EMSA): Confirm MBD4 binding to methylated CpG-containing DNA probes to study protein-DNA interactions.
• Protein Interaction Studies: Use in pull-down or co-immunoprecipitation assays to identify binding partners within the mismatch repair and epigenetic regulatory pathways.
• Western Blot Control: Use as a positive control for anti-MBD4 antibody validation.

Optimize protein concentration, buffer composition, temperature, and incubation time for each application. Include appropriate positive and negative controls in every experiment.

Quality Control and Troubleshooting

Quality Control: Recombinant Human MBD4 Protein should be verified by SDS-PAGE and/or Western blot prior to use in critical experiments. Confirm molecular weight, purity, and batch-to-batch consistency as stated on the Certificate of Analysis (CoA) provided with the product.

Common Issues and Solutions:

• Low or no activity: Verify that the protein was not subjected to excess freeze-thaw cycles. Ensure the assay buffer pH, salt concentration, and cofactors are optimized. Check that the DNA substrate is properly methylated if required.
• Protein aggregation: Centrifuge the reconstituted solution at 10,000 × g for 5 minutes at 4°C before use to remove aggregates. Consider adding a carrier protein such as BSA.
• Unexpected bands on SDS-PAGE: Minor additional bands may represent post-translational modifications or degradation products; consult the CoA for expected purity profile.

For further technical assistance, contact Aladdin Scientific technical support with your lot number and experimental details.

Frequently asked questions

What is the recommended reconstitution buffer for Recombinant Human MBD4 Protein?

Recombinant Human MBD4 Protein is typically reconstituted in sterile deionized water or a physiological buffer such as PBS supplemented with 0.1% BSA, or Tris-HCl-based buffers with glycerol to stabilize activity. Always refer to the product-specific datasheet (SKU: rp377562) for the validated reconstitution buffer and volume.

How should Recombinant Human MBD4 Protein be stored to maintain activity?

For short-term use (up to one week), store the reconstituted protein at 4°C in a tightly sealed vial. For long-term storage, aliquot into single-use volumes and store at -80°C. Avoid repeated freeze-thaw cycles, as each cycle can progressively reduce protein activity.

What applications is Recombinant Human MBD4 Protein validated for?

Recombinant Human MBD4 Protein (rp377562) is suitable for DNA glycosylase activity assays, EMSA for studying methyl-CpG DNA binding, protein-protein interaction studies (pull-down, co-IP), and as a positive control in Western blot experiments. Optimal conditions should be determined empirically for each application.

Why might Recombinant Human MBD4 Protein show reduced or no activity in my assay?

Reduced activity can result from repeated freeze-thaw cycles, protein aggregation, suboptimal buffer conditions (incorrect pH, salt, or cofactor concentrations), or use of an unmethylated DNA substrate when methylated DNA is required. Centrifuge the protein solution before use, optimize assay conditions, and verify substrate methylation status to resolve these issues.

References

1. Hendrich B, Hardeland U, Ng HH, Jiricny J, Bird A. The thymine glycosylase MBD4 can bind to the product of deamination at methylated CpG sites. Nature. 1999;401(6750):301-304. doi:10.1038/45843
2. Bellacosa A, Cicchillitti L, Schepis F, et al. MED1, a novel human methyl-CpG-binding endonuclease, interacts with DNA mismatch repair protein MLH1. Proc Natl Acad Sci USA. 1999;96(7):3969-3974. doi:10.1073/pnas.96.7.3969
3. Aladdin Scientific. Recombinant Human MBD4 Protein, SKU rp377562. Product Datasheet.

Products are supplied for research and development use only. Not for use in humans, animals, diagnosis, or therapy.