R&D Systems offers an extensive selection of cytokines, chemokines, proteases, growth factors, adhesion molecules, neurotrophic factors and developmental proteins. Proteins are available for human, mouse, rat, cotton rat, zebrafish, canine, feline, porcine, bovine, Rhesus macaque, chicken, Drosophila and viral molecules. All proteins are recombinant (unless noted otherwise) and are available carrier-free and/or in bulk quantities upon request.
Stringent manufacturing conditions and rigorous QC testing ensure superior quality, high biological activity and lot-to-lot consistency. Each protein is tested in various bioassays to confirm the biological activity is consistent with literature-based expectations of biological activity. Each new lot of protein is tested to ensure a low endotoxin level and purity greater than 90%, with most proteins greater than 95% pure. Also, our proteins do not contain sodium azide, or other preservatives, and are supplied lyophilized, for maximum stability and to facilitate easy shipping, handling and storage. Protein inserts contain essential product information and also include background information that has been published on the molecule of interest.
New proteins are released almost daily. To receive our weekly new product update e-mail, visit our Literature Request page.
Carrier-free Formulation
Most of R&D Systems proteins are available in a choice of formulation: with or without carrier protein (note: the catalog numbers of carrier free proteins have a suffix /CF to denote carrier free status and the formulation is provided on each product insert). The use of carrier [e.g. 50 µg of carrier protein (BSA) is usually added for each 1 ug of cytokine] is to increase stability and the overall shelf-life of the protein.
For some applications (eg. in vivo injection, conjugation, binding to solid support...) the presence of a carrier protein may be problematic. The use of the carrier free version is more appropriate in applications where the presence of extra protein might interfere with a reaction or stimulate a response of its own.