Tumor necrosis factor alpha (TNF-alpha), also called cachectin, is the best-know member of the TNF-family, which can cause cell death. This protein is produced by neutrophils, activated lymphocytes, macrophages, NK cells, LAK cells, astrocytes endothelial cells, smooth muscle cells and some transformed cells. TNF-alpha occurs as a secreted, soluble form and as a membrane-anchored form, both of which are biologically active. The naturally-occurring form of TNF-alpha is glycosylated, but non-glycosylated recombinant TNF-alpha has comparable biological activity. The biologically active native form of TNF-alpha is reportedly a trimer. Human and murine TNF-alpha show approximately 79 % homology at the amino acid level and cross-reactivity between the two species. Two types of receptors for TNF-alpha have been described and virtually all cell types studied show the presence of one or both of these receptor types.
Source
Escherichia coli.
Molecular Weight
Approximately 17.5 kDa, a single non-glycosylated polypeptide chain containing 158 amino acids.
Biological Activity
Fully biologically active when compared to standard. The ED50 as determined by a cytotoxicity assay using murine L929 cells is less than 0.05 ng/ml, corresponding to a specific activity of > 2.0 × 107 IU/mg in the presence of actinomycin D.
Appearance
Sterile filtered white lyophilized (freeze-dried) powder.
Formulation
Lyophilized from a 0.2 um filtered concentrated solution in 20 mM PB, 10 mM Nacl, pH 7.0.
Endotoxin
Less than 1.0 EU/ug of rHuTNF-α/TNFSF2 as determined by LAL method.
Reconstitution
We recommend that this vial be briefly centrifuged prior to opening to bring the contents to the bottom. Reconstitute in sterile distilled water or aqueous buffer containing 0.1 % BSA to a concentration of 0.1-1.0 mg/mL. Stock solutions should be apportioned into working aliquots and stored at ≤ -20 °C. Further dilutions should be made in appropriate buffered solutions.
Stability and Storage
Use a manual defrost freezer and avoid repeated freeze-thaw cycles.- 12 months from date of receipt, -20 to -70 °C as supplied.- 1 month, 2 to 8 °C under sterile conditions after reconstitution.- 3 months, -20 to -70 °C under sterile conditions after reconstitution.
