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Biotinylated Recombinant Protein L, ultra sensitivity (primary amine labeling, long spacer)  pdf  pdf  pdf

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RPL,Protein L


MABSol® Biotinylated Recombinant Protein L, Superior Sensitivity (RPL-P814R) is expressed from E.coli cells. It is the biotinylated form of Recombinant Protein L (Cat. No. RPL-P3141).


Molecular Characterization

Protein L

This protein carries a polyhistidine tag at the N-terminus.

The protein migrates as 42-47 kDa under reducing (R) condition (SDS-PAGE).


The primary amines in the side chains of lysine residues and the N-terminus of the protein are conjugated with biotins using standard chemical labeling method. A specially optimized long-spacer biotin reagent (32.5 angstroms) is used in this product to minimize potential steric hindrance.

Biotin:Protein Ratio

The biotin to protein ratio is 8-10.5 as determined by the HABA assay.


Less than 1.0 EU per μg by the LAL method.


>95% as determined by reduced SDS-PAGE.


Lyophilized from 0.22 μm filtered solution in PBS, pH7.4. Normally trehalose is added as protectant before lyophilization.

Contact us for customized product form or formulation.


Please see Certificate of Analysis for specific instructions.

For best performance, we strongly recommend you to follow the reconstitution protocol provided in the CoA.


For long term storage, the product should be stored at lyophilized state at -20°C or lower.

Please avoid repeated freeze-thaw cycles.

No activity loss is observed after storage at:

  1. 4-8°C for 12 months in lyophilized state;
  2. -70°C for 3 months under sterile conditions after reconstitution.


Biotinylated Protein L, Superior Sensitivity (Cat. No. RPL-P814R) SDS-PAGE gel

Biotinylated Protein L, Superior Sensitivity on SDS-PAGE under reducing (R) condition. The gel was stained overnight with Coomassie Blue. The purity of the protein is greater than 95%.


Biotinylated Protein L, Superior Sensitivity (Cat. No. RPL-P814R) ELISA bioactivity

Immobilized Human IgG1 containing Kappa L chain at 5 μg/mL (100 μL/well) can bind Biotinylated Recombinant Protein L, Superior Sensitivity (Cat. No. RPL-P814R) with a linear range of 0.25-5 ng/mL (QC tested).

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Protein L was isolated from the surface of bacterial species Peptostreptococcus magnus and was found to bind Ig(IgG,IgM,IgA,IgE and IgD) through L chain interaction, from which the name was suggested. Despite this wide-ranging binding capability with respect to Ig classes, Protein L is not a universal immunoglobilin-binding protein. Binding of Protein L to immunoglobulins is restricted to those containing kappa light chains (i.e., k chain of the VL domain). In humans and mice, kappa (k) light chains predominate. The remaining immunoglobulins have lambda (l) light chains. The recombinant protein contains four immunoglobulin (Ig) binding domains (Bdomains) of the native protein. Besides antibody, protein L is also suitable for binding of a wide range of antibody fragments such as Fabs, single-chain variable fragments (scFv), and domain antibodies (Dabs).


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