Positope™ Control Protein

We recommend that hydrophobic residues comprise 50% or less of all the residues in your sequence. Make sure there is at least one charged residue for every five amino acids: this is generally known to enhance the solubility of the peptide. Peptides (compared to polypeptides, which fold and bury the hydrophobic amino acids) are too small to fold, so just a few hydrophobic amino acids may leave them insoluble.

Other guidelines include:
Peptides containing multiple Cys, Met, and Trp can be hard to synthesize.
Some sequences are problematic in solid-phase peptide synthesis or cleavage and are best avoided; these include Asp-Pro sequences or stretches of amino acids that require bulky protecting groups on their side chains during synthesis.
Glycine is often good for antigenicity as it has only a hydrogen side chain; this allows for complete rotation.
Please note that we offer a Custom Antibody Production service (https://www.thermofisher.com/us/en/home/life-science/antibodies/custom-antibodies/custom-antibody-production.html) that includes the use of our proprietary Antigen Profiler and Antigen Preparation tool (https://www.thermofisher.com/us/en/home/life-science/antibodies/custom-antibodies/custom-antibody-production/antigen-profiler-antigen-preparation.html).

Most peptide antigens range in length from 12 to 16 residues and are relatively easy to synthesize. Peptides of 9 residues or shorter have been effective antigens for antibody production, but peptides longer than 16 amino acids may contain several epitopes and form secondary structures. Peptides in excess of 18 residues begin to present more synthetic challenges. Before you synthesize your peptide, we recommend doing a BLASTP search using your peptide sequence. This is to make sure that the peptide is not homologous or identical to a sequence in a completely unrelated protein in the host animal.

Please note that we offer a Custom Antibody Production service (https://www.thermofisher.com/us/en/home/life-science/antibodies/custom-antibodies/custom-antibody-production.html) that includes the use of our proprietary Antigen Profiler and Antigen Preparation tool (https://www.thermofisher.com/us/en/home/life-science/antibodies/custom-antibodies/custom-antibody-production/antigen-profiler-antigen-preparation.html).

The Positope control protein (Cat. No. R90050) is designed to be used as a positive control in western blotting for a variety of antibodies. The control protein is a 53 kDa highly purified recombinant protein that contains seven epitope tags including the Xpress, c-myc, V5, His(C-term), HisG(N-term), Thioredoxin, and GFP.

The MagicMark XP Western Protein Standard (Cat. No. LC5602) consists of peptides that contain an IgG binding domain. These peptides can be detected with your regular antibodies and provide a way for you to get good molecular weight estimations without having to rely on transferred pre-stained standards.

Find additional tips, troubleshooting help, and resources within our Protein Electrophoresis and Western Blotting Support Center.

Improper storage of antibodies can lead to:
- Degradation: Loss of activity and specificity
- Aggregation: Formation of precipitates or clumps
- Reduced performance: Poor results in assays or experiments

Find additional tips, troubleshooting help, and resources within our Antibodies and Immunoassays Support Center.

Antibody pair kits contain capture antibody, detection antibody, recombinant standard and HRP conjugate. Each contains enough reagents to process forty 96-well plates. A list of Antibody Pair Kits (https://www.thermofisher.com/us/en/home/life-science/protein-biology/protein-assays-analysis/elisa/antibody-pair-kits.html) is available by target.

Find additional tips, troubleshooting help, and resources within our Antibodies and Immunoassays Support Center.