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 TNF alpha is a member of the prototypic ligand of the TNF superfamily. This cytokine plays a central role in inflammation, apoptosis, and immune system development. The native 26 kD transmembrane protein is assembled intracellularly to form a noncovalently linked homotrimer1. Cleavage of the membrane bound TNF alpha by TACE/ADAM17 releases a 55 kD soluble trimeric form that regulates lymphoid tissue development and promotes inflammation responses2. Currently, commercially available TNF alpha proteins are produced from E coli. HumanZyme has produced TNF alpha (HuXp) from engineered human 293 cells. Both E. coli and human cell expressed proteins exhibit a molecular mass of 18 kD in SDS-PAGE. However, gel filtration studies indicate that only TNF alphaHuXp is trimeric, which has a molecular mass of 51kD, while the E coli form is not a trimer. These proteins also show distinct mobility on native gel electrophoresis. The bioactivity of TNF alpha (HuXp) was determined by the dose-dependent cytotoxity of the TNF alpha sensitive cell line L-929 in the presence of Actinomycin D. The results indicate TNF alphaHuXp is 3-fold more active than the E coli expressed protein. (ED50 of .005 vs .02) HumanZyme has developed and continues to develop a growing range of tag-free cytokines, including difficult-to-express protein members of the TGFβ1 superfamily. HumanZyme Authentic Cytokines can be used as highly preferred reagents in a wide range of applications for cancer, inflammation, stem cell research, and antibody development. References 1. Tang, P et al., 1996 Biochemistry 35:8216 2. Black, R.A et al., 1997, Nature 385:729 Human TNF alpha (Human Cell Expressed) ... |
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