Anti-Tripeptidyl Peptidase-2 Rabbit Polyclonal Antibody

Frequently Asked Questions

What molecular weight band should I expect for TPP2 on a Western blot?

TPP2 has a deduced sequence of 1,249 amino acids, corresponding to a predicted monomer molecular weight of approximately 138 kDa. On reducing SDS-PAGE, you should observe a prominent band in the 135–140 kDa range. Be aware that TPP2 natively assembles into a large spindle-shaped oligomeric complex exceeding 1 MDa in the cytosol, but under denaturing Western blot conditions the antibody detects the dissociated monomer. Some lysates may show minor higher-molecular-weight species if incomplete denaturation occurs; boiling samples thoroughly in SDS loading buffer resolves this.

What dilution should I start with for Western blot with this TPP2 antibody?

We recommend starting at 1:1000 dilution in blocking buffer for Western blot, based on validation in human cell lysates. This polyclonal antibody is supplied at 100 µg per vial. Depending on your expression level and detection system sensitivity, you may optimize between 1:500 and 1:2000. TPP2 is a relatively abundant cytosolic peptidase in many cell types, so signal intensity is usually robust at 1:1000. Always include a no-primary control and consider titrating if background appears elevated or signal is weak in your specific lysate.

Is this TPP2 antibody validated for immunohistochemistry or immunofluorescence?

Triple Point Biologics antibodies are validated for Western blot and immunohistochemistry (IHC) as part of our standard workflow. While we have not independently validated this particular TPP2 polyclonal for immunofluorescence (IF), the rabbit host and epitope accessibility often translate well to IF applications. TPP2 localizes predominantly to the cytoplasm, so you should observe diffuse cytoplasmic staining. Start with a 1:100–1:200 dilution for IHC or IF, and always include isotype or pre-immune serum controls. Antigen retrieval may improve IHC signal; citrate buffer at pH 6.0 is a reasonable starting point.

Does this antibody cross-react with mouse or rat TPP2?

This antibody is validated for human TPP2. Cross-reactivity with mouse and rat is predicted based on high sequence conservation across mammalian orthologs—human and mouse TPP2 share approximately 85–90 percent amino acid identity. However, we have not experimentally confirmed detection in mouse or rat lysates. If you plan to work with non-human samples, we recommend running a positive control human lysate in parallel and verifying that the band you observe at approximately 138 kDa in rodent samples matches the expected size and tissue expression pattern reported in the literature.

What positive control cell line or tissue should I use for TPP2 Western blots?

TPP2 is broadly expressed across mammalian tissues, with particularly high levels in metabolically active cells. HeLa, HEK293, and Jurkat whole-cell lysates serve as reliable positive controls for Western blot; all three typically yield strong signal at the expected 138 kDa band. If working with tissue, liver, kidney, and spleen lysates show robust TPP2 expression. Load 20–30 µg total protein per lane as a starting point. Because TPP2 is cytosolic and abundant, you should not require enrichment or subcellular fractionation for detection in standard whole-cell extracts.

Are there known isoforms or splice variants of TPP2 I should be aware of?

The primary TPP2 transcript encodes the full-length 1,249-amino-acid protein, and this is the predominant isoform detected in most tissues. Minor splice variants have been reported in transcript databases, but their expression at the protein level is either very low or unconfirmed. You should expect a single major band at approximately 138 kDa on Western blot. If you observe additional bands, consider the possibility of proteolytic cleavage, post-translational modification, or non-specific binding. Running a peptide competition assay or siRNA knockdown can help confirm specificity of any unexpected bands.

How should I store this TPP2 antibody and what is the expected shelf life?

Store the antibody at –20°C in small aliquots to avoid repeated freeze-thaw cycles, which can reduce titer and increase aggregation. The polyclonal format is supplied in a stabilized buffer; shelf life is typically 12–24 months when stored properly. Avoid prolonged exposure to room temperature. For day-to-day use, you may keep a working aliquot at 4°C for up to one month. Do not add sodium azide if you plan to use the antibody for applications involving HRP-conjugated secondary reagents, as azide inhibits peroxidase activity. Centrifuge briefly before use if you observe any precipitate.

What sample preparation considerations are important for detecting TPP2 by Western blot?

TPP2 is a cytosolic serine peptidase, so standard RIPA or NP-40 lysis buffers work well. Include protease inhibitors—particularly serine protease inhibitors such as PMSF or AEBSF—to prevent autolysis or degradation during lysis, though TPP2 itself is relatively stable. Avoid prolonged incubation at room temperature after lysis. Boil samples in reducing SDS sample buffer for five minutes to ensure complete denaturation and monomer dissociation, as TPP2 forms large native oligomers. Load 20–30 µg total protein per lane and transfer to PVDF or nitrocellulose; standard transfer conditions are sufficient for this 138 kDa target.