Description
RP2-Serpin-B13 is a polyclonal antibody made to the serine proteinase inhibitor headpin/hurpin. The antibody is made to a synthetic peptide based on the reactive center loop area of human serpin-B13. 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
Serpin-B13 is a serine proteinase inhibitor of the ovalbumin-like B clade of serpins. Serpin-B13 was discovered as headpin, a protein of head and neck cancers produced by keratinocytes, as hurpin, a skin-specific protein downregulated by UV light, and as PI13 (proteinase inhibitor-13), a skin protein upregulated in psoriasis. As headpin, serpin-B13 was reported to suppress angiogenesis in a mouse corneal neovascularization model, and to inhibit cathepsins K and L. As hurpin, serpin-B13 was shown to be a selective inhibitor of cathepsin-L, and to protect keratinocytes from UV-induced apoptosis. Hurpin is also reported to be overexpressed in cutaneous carcinomas, although as headpin it is reportedly downregulated in head and neck cancers. Most of the serpins (SERine Proteinase Inhibitors) are serine proteinase inhibitors; although not all serine proteinase inhibitors are serpins, and visa versa. The overall structural shape of the B clade of serpins most resembles ovalbumin, which is not considered to be a serine proteinase inhibitor. The serpins share a reactive center loop motif: a substrate bait loop which, when cleaved, confers a remarkable molecular shift in the serpin molecule, and traps the enzyme. This mousetrap method works because the uncleaved serpin molecule is in tension, and cleaving the loop allows a more energetically favorable state to exist. The cleavage site in serpin-B13 is Thr356-Ser357 of the 391amino acid sequence. The original sequence described was 391 amino acids in length, with predicted mass of 44.3 kDa and pI of 5.36. A single amino acid deletion of 390 amino acids has been reported. Splice variants of 408, 356, 339 and 255 amino acids have also been reported, with predicted masses of 46.2, 40.3, 38.4 and 28.6 kDa respectively, and pIs of 5.69, 5.81, 5.45 and 5.83 respectively. The 408 and 356 amino acid forms have an aminoterminus 17 residues longer than the 391, 390 and 339 amino acid forms. The 255 amino acid long form starts at the second methionine relative to the 391 amino acid form, and has a different 17 amino acid aminoterminus than the other serpin-B13 isoforms. The 339 and 356 amino acid forms have a deletion in residues 204-256, of the 391 amino acid form. All of the isoforms contain the reactive center loop, but it is unknown if the shorter forms are active serpins. RP2-Serpin-B13 recognizes all of the listed serpin-B13 isoforms. 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 at -20C.
