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Who is HumanZyme?
We specialize at manufacturing authentic human proteins from human 293 cells in a serum free, chemical defined environment. It is Xeno-free, since essentially all our HumaXpress™ products are recombinant, animal component-free, while at the same time, solely from human origin. There are no single trace elements introduced by exotic expression in E. coli, yeast and CHO. Additionally, the loyal internal machinery in human systems means our products will have bona-fide post-transcriptional modifications, such as phosphorylation and glycosylation, among others. From the user perspective, that translates into worry-free, since the effect and phenomenon you observe are physiologically relevant as well as reproducible lot to lot, erasing all the concerns about potential contaminants from other sources.
What is the ED50 Range and how is it compared to specific activity in units/mg?
We supply recombinant cytokines in µg (or mg) with a specific ED50 range rather than as specific activity in units per vial. The ED50 is defined as the cytokine concentration at which the bioassay activity is 50% of the maximum response. Bioassay is a measurement of biological response, such as cell proliferation assay, functional ELISA or an enzymatic assay, to a specific protein. Due to the variable nature of bioassays, the same cytokine preparation may not give you the same ED50 value at different occasions. In particular, any variation in a bioassay condition such as cell densities, age or even passage numbers may lead to variable results.
Humanzyme report typical ED50 range on datasheet for a given cytokine. ED50 is accurate only when the cytokine dose-response curves are sigmoidal shape. The formula for converting the ED50 in ng/ml to specific activity in units/mg is:
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