DPP-3 (Recombinant)

Frequently Asked Questions

What molecular weight band should I expect for recombinant DPP-3 on SDS-PAGE or Western blot?

The DPP-3 polypeptide (UniProt Q9NY33) is 737 amino acids with a predicted unmodified MW of ~83 kDa. Because this recombinant is expressed in HEK293 cells, N-linked glycosylation adds variable mass; expect a diffuse band migrating at approximately 90–100 kDa under denaturing conditions. A smear or doublet in this range is normal and reflects heterogeneous glycosylation, not degradation. If you observe a sharp ~83 kDa band, partial deglycosylation during sample prep is the likely cause. Running 100–200 ng per lane is sufficient to visualize by Coomassie or silver stain.

Is recombinant DPP-3 full-length or a truncated active fragment, and does it require any processing to become active?

This recombinant corresponds to the full-length human DPP-3 sequence (residues 1–737, UniProt Q9NY33). DPP-3 is a cytosolic zinc metalloprotease that does not undergo signal-peptide cleavage or propeptide removal; the full-length form is the catalytically active species. No additional processing or activation step is required after thawing. Catalytic activity depends on the coordinated zinc ion at the HEXXGH motif; avoid chelating agents such as EDTA or EGTA in assay buffers, as even low micromolar concentrations will inhibit the enzyme irreversibly.

Which fluorogenic substrate works best for a DPP-3 activity assay, and what are recommended reaction conditions?

Arg-Arg-β-naphthylamide (Arg-Arg-βNA) is the standard fluorogenic substrate for DPP-3 activity assays. Use 50–200 µM substrate in 50 mM Tris-HCl pH 7.5, 150 mM NaCl at 37°C; β-naphthylamine release is monitored continuously at Ex 335 nm / Em 410 nm. Published Km values for this substrate are in the 50–150 µM range depending on pH and salt. Start with 5–20 nM recombinant DPP-3 per reaction and optimize enzyme concentration to keep initial-rate conditions linear (< 15% substrate consumed over the assay window).

Can I use recombinant DPP-3 to measure inhibitor IC50 values, and what starting enzyme concentration is recommended?

Yes. For IC50 determination, titrate inhibitor across 8–10 concentrations spanning at least 3 log units and incubate with enzyme for 15–30 minutes at room temperature before adding substrate. Use 5–10 nM recombinant DPP-3 with 100 µM Arg-Arg-βNA in 50 mM Tris-HCl pH 7.5, 150 mM NaCl, 37°C. Keep enzyme concentration well below the Km to avoid tight-binding artifact in apparent IC50 calculations. Include 0.01–0.05% BSA to reduce non-specific adsorption to plate surfaces, particularly at low nanomolar inhibitor concentrations. Run each compound in duplicate across at least two independent plates.

Does recombinant DPP-3 cleave angiotensin II, and how do I confirm peptidase activity on natural substrates?

DPP-3 cleaves angiotensin II (Asp-Arg-Val-Tyr-Ile-His-Pro-Phe) by sequentially removing N-terminal dipeptides. Activity on angiotensin II can be confirmed by reverse-phase HPLC or LC-MS/MS monitoring the disappearance of the parent octapeptide and appearance of the Val-Tyr-Ile-His-Pro-Phe hexapeptide product. Use 1–5 µM angiotensin II with 50–100 nM recombinant DPP-3 in 50 mM Tris-HCl pH 7.5, 150 mM NaCl at 37°C. Leu-enkephalin and Met-enkephalin are also validated substrates if you need shorter peptides for parallel selectivity profiling.

How much recombinant DPP-3 should I load as a Western blot positive control when validating antibody RP-DPP3?

Load 50–200 ng of recombinant DPP-3 per lane alongside your cell lysate samples. At 100 ng, the matched rabbit polyclonal antibody RP-DPP3 (see /anti-dpp-3-rabbit-polyclonal-antibody) produces a clear band in the 90–100 kDa region under standard ECL conditions. Because the recombinant is HEK293-expressed, it carries the same glycosylation pattern as endogenous human DPP-3, so the recombinant band co-migrates directly with the endogenous band in human cell lysates — no band-shift artifact to account for during validation.

Can I use recombinant DPP-3 paired with antibody RP-DPP3 for antibody specificity validation or immunoprecipitation input controls?

Yes, this is a straightforward pairing. The recombinant protein (REC-DPP3) and antibody (RP-DPP3) were developed in the same lab and are guaranteed compatible for Western blot positive controls. For IP input controls, spike 100–500 ng recombinant DPP-3 into lysate before immunoprecipitation with RP-DPP3 to confirm pull-down efficiency. For dot-blot or slot-blot specificity checks, 10–50 ng is sufficient. Note that RP-DPP3 is a rabbit polyclonal; if your secondary antibody or blocking conditions require optimization, the recombinant provides a reliable, concentration-defined positive control for that troubleshooting.

How should I store and handle recombinant DPP-3 to preserve activity, and what is its shelf life?

Recombinant DPP-3 is supplied in 50 mM Tris-HCl pH 7.5, 150 mM NaCl, 10% glycerol — no reconstitution required. Store at -20°C in single-use aliquots immediately upon receipt. Repeated freeze-thaw cycles progressively reduce metalloprotease activity; plan aliquot sizes to match your typical experiment. Shelf life is 12 months at -20°C when handled correctly. For same-day experiments, thawed enzyme can be held on ice for up to 4 hours without significant activity loss. Avoid diluting into buffers containing EDTA, EGTA, or high concentrations of reducing agents, as these chelate the catalytic zinc and inactivate the enzyme.