Description
RP2-Serpin-B8 is a polyclonal antibody made to the serine proteinase inhibitor PI8. The antibody is made to a synthetic peptide based on the reactive center loop (RCL) of human serpin-B8. 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-B8, also known as CAP2, Cytoplasmic Antiproteinase-2, and PI8, Proteinase Inhibitor-8, is a serine proteinase inhibitor of the ovalbumin-like B clade of serpins. Serpin-B8 was first discovered in the placenta in a search for serpins similar to serpin-B6. Chondrocyte-like cells were shown to have enhanced expression of serpin-B8 after tumor necrosis factor-(alpha) stimulation. Megakaryocytes have been shown to synthesize serpin-B8 and the protein is stored in platelets prior to release. Serpin-B8 has also been shown to be elevated in the remodeling kidney, and message has been detected in normal human spleen, pituitary gland, epidermis, lung, liver, stomach, pancreas, and the mucosa oropharynx. By immunohistochemistry, serpin-B8 was detected mainly in the nuclei of squamous epithelium. 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-B8 is thought to be Arg339-Cys340 of the 374 amino acid sequence. Serpin-B8 has been shown to inhibit trypsin and thrombin. In addition to the RCL cleavage site, serpin-B8 has two paired dibasic consensus sites which flank the RCL cleavage sites for trypsin, chymotrypsin and thrombin, and allow serpin-B8 to inhibit furin. Other proprotein convertases may be inhibited by serpin-B8, but have yet to be tested. The original sequence described was 374 amino acids in length, with predicted mass of 42.79 kDa and pI of 5.28. A 242 amino acid long form that terminates before the RCL, and thus would be inactive as a proteinase inhibitor, has a predicted mass of 27.7 kDa and a pI of 4.61. The relative abundance or distribution of the smaller form is unknown. 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.
