Anti-MMP-12M Rabbit Polyclonal Antibody

Frequently Asked Questions

What is the expected molecular weight of MMP-12 on Western blot?

MMP-12 is synthesized as a preproenzyme of approximately 54 kDa. On Western blot, you may observe the proenzyme form at around 54 kDa and the catalytically active mature form at approximately 45 kDa following proteolytic removal of the prodomain. The band pattern depends on cellular activation state and whether samples contain extracellular matrix where processing occurs. Macrophage lysates typically show both forms, while conditioned media may be enriched for the mature species. This antibody is raised against a broad epitope spanning residues of the mature protein, so it should recognize both forms.

What starting dilution should I use for Western blot with this MMP-12M antibody?

We recommend starting at 1:1000 dilution for Western blot, as validated in our hands with standard macrophage lysates. This dilution typically provides clear signal with low background when using standard chemiluminescence detection. If your expression level is low or you are working with tissue lysates rather than macrophage-enriched samples, you may need to concentrate to 1:500. Conversely, for highly activated macrophage cultures or inflammatory tissue, 1:2000 may suffice. Always include a positive control lysate from PMA-stimulated macrophages or LPS-treated cells to confirm antibody performance during optimization.

Does this antibody work for mouse and rat MMP-12 detection?

This antibody has been validated on human MMP-12. Cross-reactivity with mouse and rat is predicted based on sequence homology in the immunogen region but has not been experimentally confirmed in our laboratory. Human MMP-12 shares approximately 80 percent sequence identity with mouse and rat orthologs across the mature protein. If you are working with mouse or rat samples, plan to empirically validate the antibody with known positive controls such as thioglycollate-elicited peritoneal macrophages or LPS-stimulated alveolar macrophages, and be prepared to optimize dilution and blocking conditions independently.

What tissue or cell type should I use as a positive control for MMP-12 expression?

Macrophages are the canonical positive control for MMP-12 expression. Use human monocyte-derived macrophages or THP-1 cells differentiated with PMA, ideally stimulated with LPS or inflammatory cytokines to enhance expression. Lung tissue from emphysema models or atherosclerotic plaque tissue also express MMP-12 at detectable levels. For negative controls, consider fibroblasts or epithelial cell lines, which express MMP-12 minimally under basal conditions. Including both positive and negative controls on every blot is essential because MMP-12 expression is tightly regulated and often undetectable in resting or non-macrophage cell types.

Can this antibody distinguish between active and pro-MMP-12 forms?

This polyclonal antibody is raised against a large fragment of the mature MMP-12 protein, so it recognizes epitopes present in both the proenzyme and the active forms. It will not selectively detect only the active species. On Western blot, you can infer activation status by molecular weight: the 54 kDa band corresponds to the zymogen and the 45 kDa band to the active proteinase after prodomain cleavage. If you need to distinguish active MMP-12 functionally rather than by size, consider parallel zymography or activity-based probes, as this antibody is not conformation-selective for the active site.

What sample preparation is recommended for detecting MMP-12 in tissue lysates?

MMP-12 is a secreted proteinase that localizes to the extracellular matrix, so sample preparation depends on your experimental question. For total cellular MMP-12, use RIPA or similar stringent lysis buffer containing protease inhibitors, including EDTA or EGTA to inhibit MMP activity during extraction. For secreted MMP-12, collect conditioned culture media or perform sequential tissue extraction with mild detergent to isolate the extracellular fraction. Avoid boiling samples excessively if you wish to preserve higher-order structure. Include a reducing agent such as DTT or beta-mercaptoethanol to fully denature the protein for SDS-PAGE analysis.

How should I store this MMP-12M antibody to maintain stability?

Store the antibody at minus 20 degrees Celsius in single-use aliquots to avoid repeated freeze-thaw cycles, which can reduce titer and increase aggregate formation. After the first thaw, the working aliquot can be kept at 4 degrees Celsius for up to one month if sodium azide or another preservative is present. Do not store diluted antibody in working solution for more than a few days. If you observe a decline in signal over time, prepare a fresh aliquot from frozen stock. This is a rabbit polyclonal, so batch-to-batch variation is inherent; record lot numbers and optimize dilution with each new vial.

Does MMP-12 have splice isoforms I should be aware of when interpreting blots?

MMP-12 is encoded by a single gene with no widely reported alternative splice variants that produce distinct protein isoforms. The primary transcript encodes the full-length preproenzyme. Variability in Western blot band patterns is almost always due to post-translational processing rather than alternative splicing: the preproenzyme undergoes signal peptide cleavage and subsequent prodomain removal to generate the active enzyme. Glycosylation is minimal in MMP-12 compared to some other MMPs. If you observe multiple bands, consider proteolytic processing intermediates, degradation products, or dimer formation under non-reducing conditions rather than assuming splice variants.