Can I use your antibodies for matched pair ELISA with a standard from another company?
The answer is yes but with some precautions. One problem we have observed with using antibodies from one company and standard from another company is that there can be differences in immunological recognition (or the binding between antibody and recombinant protein). This can happen if there is a difference in the folding or sequence of the recombinant protein used as the standard vs. the recombinant protein used as the immunogen for the antibody. Protein folding or sequence differences in the antibody-binding region can lead to poor or no recognition of the standard.
Has X product been used for Y application that is not listed on the data sheet?
If you do not see a specific application listed on our data sheet and R&D Systems has no further in-house data, Technical Service can check their reference database to see if any other researchers have published this use, sample type, and/or species with a specific product.
What are R&D Systems matched antibody pairs?
R&D Systems matched antibody pairs are a do-it-yourself type product. R&D Systems recommends the end user have expertise in immunoassay building before attempting to use these products. The end user must empirically determine the optimal concentrations for the capture and detection antibodies. Amounts of antibodies supplied are not normalized to give the same number of plates. R&D Systems recombinant cytokines are not calibrated by ELISA and therefore must be mass calibrated by ELISA before use.
What epitope does this monoclonal antibody recognize?
R&D Systems does not epitope map its antibodies. The antibody is generated using the entire immunogen listed on the data sheet.
What epitope does this polyclonal antibody recognize?
Polyclonal antibodies have multiple epitope recognition. The antibodies are generated using the entire immunogen stated on the package insert as both the immunogen and, in many cases, the affinity ligand for purification.
What is a competitive ELISA?
In the competitive immunoassay approach, which is also termed "labeled analyte" technique, there exists a competition between the unlabeled antigen and labeled antigen for a limited amount of binding sites on the binder (antibody). In general, R&D Systems competitive ELISAs are labeled with alkaline-phosphatase.
What is a direct ELISA?
In a direct ELISA, a plate is coated with the analyte of interest and a detection antibody is used to verify the presence of the analyte of interest. This is only considered a semi-quantitative technique when compared with a recombinant standard. The direct ELISA uses the method of directly labeled antibody. Microwell plates are coated with a sample containing the target antigen, and the binding of labeled antibody is quantitated by a colorimetric, chemiluminescent, or fluorescent end-point.
What is a sandwich ELISA?
A sandwich ELISA uses an immobilized capture antibody specific for the analyte of interest in a sample. The analyte of interest is then bound to the immobilized antibody. A labeled secondary antibody, specific for the analyte of interest, is used for detection. The analyte of interest is "sandwiched" between the two antibodies. Values are quantitative when compared with a standard curve.
What is the difference between AB###, AF###, BAF###, MAB###, and BAM### Antibody designations?
AB### designated antibodies are protein G purified and have a total IgG fraction. AF### designated antibodies, in addition to being protein G purified, are also antigen affinity chromatography purified. Therefore, AF### antibodies are IgG specific only to the antigen, whereas AB### designated antibodies may contain IgG not specific for the analyte of interest. Antibodies that have the designation MAB### are monoclonal antibodies. BAF### and BAM### designated antibodies are the biotinylated versions of the AF### and MAB### designated antibodies, respectively.
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 inserts 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.
What is the molecular weight of IgG?
An IgG protein is comprised of two heavy chains that are approximately 55 kDa each and two light chains that are approximately 25 kDa each for a total molecular weight of approximately 160 kDa.
Which ELISA plates does R&D Systems recommend for its DuoSets and Matched Antibody Pairs?
For years, we have recommended ELISA plates from Costar (Catalog # 2592). These plates are now sold as an accessory to the DuoSet line. We offer both clear and black microplates along with plate sealers.
| DY990 |
Clear 96-well polystyrene microplates |
25/pack |
| DY991 |
Black 96-well polystyrene microplates |
25/pack |
| DY992 |
Plate Sealers |
100/pack |
For added convenience, try EvenCoat™, goat anti-mouse IgG microplates, Catalog # CP001 & CP002. EvenCoat goat anti-mouse IgG microplates are clear, pre-blocked 96-well polystyrene microplates coated with goat-derived antibody specific for the Fc region of mouse IgG. These plates may be used as a solid support for most sandwich ELISAs utilizing a mouse IgG capture antibody and a non-mouse IgG detection antibody. Other applications include competitive ELISA, IgG isotyping, and hybridoma screening/selection.
EvenCoat Microplates may be used with most DuoSet ELISA Development Kits. Check your DuoSet product insert to see if it can be used with EvenCoat Microplates. If there is no indication that it has been tested, please contact our Technical Service department for more information.
What is trehalose and why is it in the formulation?
Trehalose is a non-reducing sugar (MW 342.1) and, therefore, does not react with amino acids or proteins as part of the Maillard reaction. It is found in nature in many plants and animals. Trehalose has been reported to be one of the most effective sugars for stabilizing proteins against damage caused by freezing. Trehalose makes the protein more resistant to moisture gain, resulting in a product that is less likely to precipitate when reconstituted.
What is the rationale for using trehalose to stabilize proteins?
- Protection of proteins during freezing and dehydration
- Non-reducing
- Remain amorphous during lyophilization
- Has been used in approved parenteral therapeutics
Will trehalose affect my conjugation reaction?
It is possible that the presence of trehalose will interfere in the successful conjugation of a protein. This will depend on the method used, and the customer should investigate this prior to purchasing the product.
Will trehalose affect the animal I inject it into?
Unlikely; it has been approved as an excipient for use in human injectable drugs.
Will trehalose affect the performance of the protein or antibody in my specific application?
We do not know how it will affect all potential applications. We have seen no adverse effect in our bioassays. Customers are advised to run a control in their assay to determine if the concentration of trelahose in the cytokine or antibody has any adverse effect.