- At what concentration should the isotype control antibody be used in a flow cytometry experiment?
- Ideally the concentration of the isotype control antibody should match the concentration of the analyte specific antibody. One could also titrate both the isotype control and the analyte specific antibodies and choose the concentration for each that gives the best signal to noise ratio.
- How do I choose an appropriate isotype control?
- An isotype control is an antibody that is the same IgG isotype as the primary antibody, but raised against an irrelevant antigen. An isotype control should produce negative staining results, thereby giving you confidence in the staining observed with the target-specific antibody. The Supplemental Products tab on the product page indicates appropriate isotype controls for that product. Here is an example: https://www.rndsystems.com/products/mouse-cd4-apc-conjugated-antibody-gk15_fab554a#supplemental-products
- What is a direct ELISA?
- In a direct ELISA, a plate is coated with the analyte of interest and a labeled detection antibody is used to verify the presence of the analyte. The direct ELISA may use a colorimetric, chemiluminescent, or fluorescent reporter.
- What is the expiration of R&D Systems proteins and antibodies?
- R&D Systems has established a policy of not limiting the useful life of a product by providing an expiration date or manufacture date for our protein and antibody products. Under proper storage conditions, proteins and antibodies tend to be stable for many years. These conditions include storing proteins as lyophilized powder, storing the product frozen (-20° C or -80° C) at protein concentrations of greater than 0.1 mg/mL, and limiting the number of freeze/thaw cycles. Please see individual product datasheets for specific instructions. Routine quality control testing by our company ensures that all products have acceptable biological activities at the time of sale. R&D Systems cannot control storage conditions of a product upon receipt by the end user. In lieu of an expiration date, we choose to offer a warranty on our protein and antibody products. All products supplied by R&D Systems are warranted to meet or exceed our published specification when used under normal conditions in your laboratory.Typically, this warranty will extend 6-12 months from time of purchase. Please see individual datasheets for specific stability claims. If the product fails during the stated period, a replacement product or credit will be issued. For details regarding our warranty please see //www.rndsystems.com/customer_service_legal.aspx.
- Will trehalose affect the performance of the protein or antibody in my specific application?
- We generally have not seen adverse effects in our bioassays or other approved applications. However, customers are advised to run a control in their assay to determine if the concentration of trehalose in the protein or antibody formulation has any adverse effects.
- What is trehalose and why is it in the formulation?
- Trehalose is a non-reducing sugar and does not react with amino acids or proteins as part of the Maillard reaction. It is added to stabilize antibodies and other proteins against damage caused by freezing. It can also make proteins more resistant to moisture when lyophilized, resulting in a product that is less likely to precipitate when reconstituted.
- Will trehalose affect my conjugation reaction?
- Trehalose is not usually expected to interfere with conjugation; we often successfully conjugate antibodies which are bottled with Trehalose using primary amine to NHS ester coupling chemistry. However, for optimal conjugation performance, it is best practice to perform buffer change to remove trehalose using desalting column to a compatible conjugation buffer prior to coupling reaction.
- Will trehalose included in the formulation affect the animal if it is injected?
- Trehalose is unlikely to have an effect in vivo. It has been approved as an excipient for use in human injectable drugs.