FITC-Labeled Recombinant Protein L

INTRODUCTION

QC & Assay Protocol

Citation & Background

Synonym
RPL,Protein L
Source
FITC-Labeled Recombinant Protein L (RPL-PF141) is expressed from human HEK293 cells. It is the FITC labeled form of Recombinant Protein L (Cat # RPL-P3141).
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Molecular Characterization
FITC-Labeled Recombinant Protein L is fused with a polyhistidine tag at the N-terminus. The reducing (R) protein migrates as 42-47 kDa in SDS-PAGE.
Conjugate
FITC

Excitation source: 488 nm spectral line, argon-ion laser

Excitation Wavelength: 488 nm

Emission Wavelength: 535 nm
Labeling
The primary amines in the side chains of lysine residues and the N-terminus of the protein are conjugated with FITC using standard chemical labeling method. The residual FITC is removed by molecular seive treatment during purification process.
FITC:Protein Ratio
The FITC to protein molar ratio is 5-7 as determined by

Endotoxin
Less than 1.0 EU per μg by the LAL method.
Purity
>95% as determined by SDS-PAGE.
Formulation
Lyophilized from 0.22 μm filtered solution in PBS, pH7.4. Normally trehalose is added as protectant before lyophilization.
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Reconstitution
Please see Certificate of Analysis for specific instructions.
For best performance, we strongly recommend you to follow the reconstitution protocol provided in the CoA.
Storage
For long term storage, the product should be stored at lyophilized state at -20°C or lower.
Please protect from light and 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.

SDS-PAGE

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

Bioactivity

Immobilized Yervoy Ipilumimab at 10 μg/mL (100 μL/well) can bind FITC-Labeled Recombinant Protein L (Cat. No. RPL-PF141) with a linear range of 20-156 ng/mL (QC tested).

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Citations
- Impact of site-specific conjugation of scFv to multifunctional nanomedicines using second generation maleimide
  Authors: Hervé-Aubert K, et al.
  Journal: Bioconjug Chem 2018
  Application: Immunofluorescence
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- Targeting HER2-breast tumors with scFv-decorated bimodal nanoprobes
  Authors: Alric C, et al.
  Journal: J Nanobiotechnology 2018
  Application: Immunofuorescence
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Background
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).
References
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