Description
RP2-Tripeptidyl Peptidase-II is a rabbit polyclonal antibody made to the serine proteinase Tripeptidyl Peptidase-II. The antibody is made to a synthetic peptide based on the catalytic domain of human Tripeptidyl Peptidase-II. The antibody has been peptide-affinity purified, concentrated to 1.0 mg/ml, with the addition of 0.05% sodium azide as preservative and 50% glycerol as cryoprotectant.
Use
Tripeptidyl Peptidase-II, also known as TPP2 and Tripeptidyl Aminopeptidase, is a subtilisin-like serine protease in the clan SB, family S8A in the MEROPS classification system. The homology between TPP1 and TPP2 is very low, and the only thing the two enzymes share in common is a preference for removing the 3 aminoterminal peptides from oligopeptides. Whereas TPP1 is a lysosomal serine peptidase, TPP2 is cytoplasmic, as well as membrane bound in some cell types. TPP2 also forms large homomeric aggregates of dozens of subunits, which take on a tertiary structure of a twisted rope with a central pore. Superficially this homomultimer resembles the tricorn protease complex, and the TPP2 unit is thought to process oligopeptides that are released from the proteosome complex. The membrane bound form is implicated in cleaving the satiety hormone cholecystokinin 8, thus promoting fat formation. The proteinase activity of TPP2 was described primarily as an exopeptidase, with preferences for 15-40 residue oligopeptides, and a broad substrate specificity hindered only by pentultimate proline residues. Endoproteinase activity has also been reported, albeit at much lower rates. The tertiaty structure is credited for maintaining the substrate specificity of TPP2, and monomers of TPP2 are thought to be essentially inactive (although study of the complex activity against native substrates is difficult to accomplish). The TPP2 catalytic domain contains the Asp-His-Ser catalytic triad of the serine proteinases, but with a 200 residue insertion between the aspartic acid and histidine residues. This structure is reminiscent of the matrix metalloproteinases, where MMP-2 and MMP-9 have a fibronectin-like insertion in the catalytic domain, thought to be involved in substrate binding. Curiously, TPP-2 antibodies were shown to cross-react with fibronectin, and the specific residues mapped to residues 13-26 and 440-449, which bear some resemblance to the cell-binding regions of fibronectin. TPP2 is a 1249 amino acid monomer, with mass of 138.4 kDa and a pI of 5.9. The large homomultimers are several megadaltons in size. A recommended starting concentration for Western blots is 1:1,000 when using colorimetric substrates such as BCIP/NBT, and 1:5,000 for chemiluminescent substrates. Higher concentrations of antibody may be needed for samples from more distantly related species. FOR RESEARCH USE ONLY; NOT FOR USE IN HUMANS.
Storage
The undiluted antibody solution is stable for approximately 12 months at -20C.
