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Product Code: 03-96
Price: €425

  • All necessary reagents for 8x12 microwells
  • Sufficient for analysis of 44 samples in duplicate.
  • Includes full instruction manuals.


 

Documents

pdf document Product Sheet

pdf document MSDS

pdf document Kit Insert

 

FAQ

 

 


What Staph aureus strain is the Protein A reference standard from?

We originally used protein A purified from strain A676. We believe that it is good that the customer has the possibility to obtain the reference material independently of IMMUNSYSTEM AB. We thus use recombinant protein A from GE Healthcare (Uppsala, Sweden) as a reference in the kit. Originally, we chose GE Healthcare (Pharmacia at that time) as they were the first company to market protein A and they had the patent for purifying protein A on human IgG sepharose. The patent has now expired. They are also one of the largest producers of recombinant protein A. GE Healthcare purifies their protein A on Human IgG sepharose.


What is the sensitivity of the assay?

The sensitivity in a sample without IgG is typically 0.1 ng protein A/ml. For an IgG containing sample, the sensitivity is 1 ppm. For example if you have a sample containing 0.2 mg IgG/ml the detection limit is 0.2 ng protein A/ml.


Can the kit be used to detect native Protein A?

Yes


What do you considered high concentrations of human IgG?

The kit has been developed to work accurately with human IgG concentration up to 5 mg/ml. We have not tested samples with higher concentration, therefore we can not guarantee the accuracy of the assay at those levels.


How should the standard curve be prepared?

Despite the boiling of the samples there is some interference by IgG in the samples. That is why we recommend that the user adds antibodies to the standard curve in a similar concentration to that in the samples. The interaction between protein A and monoclonal antibodies varies depending on the class and subclass of the antibody. For many researchers it is probably sufficient to add any kind of monoclonal antibody to the samples, we recommend that the customer use the same antibody in the standard as in the samples. If the antibody used for the standard curve is purified on a protein A column it may contain some protein A thus adding protein A to the standard. It is therefore better to use an antibody in the standard curve that has been purified with another method than protein A. The antibody in the standard curve does not have to be purified, but the antibody concentration should be similar to the samples.


We use a cell line that produces Human IgG1. Which Protein A ELISA kit do I need?

You should note that there is only one kit, but that it can be used with two different protocols. For your specific application you should run according to the protocol for samples containing IgG.


What is the storage stability of the coated and blocked plates?

The kit is good until the expiration date, which will generally be at least 6 months from the purchase date. The stability is 1.5 years from the date of manufacture when stored at +4C.


Can the protein A reference standard be prepared early and stored in cold condition in plastic tubes?

No, the protein A standards should be freshly prepared. We do not have any separate performance/stability studies with pre-prepared Protein A standards; therefore we can not guarantee the performance/stability of early prepared Protein A standards.


Does the salt concentration in samples affect the result?

Probably not, the typical working solution for the assay contains 0.15 M NaCl (in PBS-Tween).


Does the detergent have to be added to the samples?

Yes, it is very important to add detergent (0.05% Tween 20) in both samples and Protein A standards to recover the accurate amount of Protein A. Protein A range between 0.1 to 100 ng/ml has been tested for recovery with and without detergent. If detergent was not added, more than 90% of the Protein A were coated into the walls of the sample tubes. You will still detect Protein A in samples with largeamounts(>0.1 g/ml) because the samples have an excess of Protein A. If the samples are not "treated" with Tween 20, you will measure the residual Protein A level after an unknown amount have been coated into the tubes walls.


How many samples can you analyze with one kit?

The kit contains one microtitre plate with 96 wells. Often, 16 wells are used for standards (duplicate samples) which leave 80 wells for samples.


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