Recombinant Human Lipocalin-1 Protein, CF

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Recombinant Human Lipocalin-1 Protein, CF Summary

Product Specifications

>95%, by SDS-PAGE visualized with Silver Staining and quantitative densitometry by Coomassie® Blue Staining.
Endotoxin Level
<1.0 EU per 1 μg of the protein by the LAL method.
Measured by its ability to inhibit active Cathepsin V cleavage of a fluorogenic peptide substrate Z-LR-AMC (Catalog # ES008). The IC50 value is <400 nM, as measured under the described conditions.
Mouse myeloma cell line, NS0-derived human Lipocalin-1 protein
His19-Asp176, with a C-terminal 10-His tag
Accession #
N-terminal Sequence
Predicted Molecular Mass
19 kDa
20-22 kDa, reducing conditions

Product Datasheets

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Carrier Free

What does CF mean?

CF stands for Carrier Free (CF). We typically add Bovine Serum Albumin (BSA) as a carrier protein to our recombinant proteins. Adding a carrier protein enhances protein stability, increases shelf-life, and allows the recombinant protein to be stored at a more dilute concentration. The carrier free version does not contain BSA.

What formulation is right for me?

In general, we advise purchasing the recombinant protein with BSA for use in cell or tissue culture, or as an ELISA standard. In contrast, the carrier free protein is recommended for applications, in which the presence of BSA could interfere.


Formulation Supplied as a 0.2 μm filtered solution in Tris and NaCl.
Shipping The product is shipped with polar packs. Upon receipt, store it immediately at the temperature recommended below.
Stability & Storage: Use a manual defrost freezer and avoid repeated freeze-thaw cycles.
  • 6 months from date of receipt, -20 to -70 °C as supplied.
  • 3 months, -20 to -70 °C under sterile conditions after opening.

Assay Procedure

  • Assay Buffer: 50 mM Sodium Acetate, 0.15 M NaCl, pH 5.5
  • Cathepsin Buffer: 50 mM Sodium Acetate, 0.15 M NaCl, 10 mM DTT, pH 5.5
  • Substrate Buffer: 50 mM Sodium Acetate, 0.15 M NaCl, 5 mM DTT, pH 5.5
  • Recombinant Human Lipocalin-1 (rhLipocalin-1) (Catalog # 1708-PI)
  • Recombinant Human Cathepsin V (rhCathepsin V) (Catalog # 1080-CY)
  • Substrate: Z-Leu-Arg-AMC (Catalog # ES008)
  • F16 Black Maxisorp Plate (Nunc, Catalog # 475515)
  • Fluorescent Plate Reader (Model: SpectraMax Gemini EM by Molecular Devices) or equivalent
  1. Prepare a curve of rhLipocalin-1 (MW: 18,805 Da) in Assay Buffer. Make the following serial dilutions:  40,000, 10,000, 4000, 1000, 500, 250, 125, 50, 12.5, and 6.25 nM.
  2. Dilute rhCathepsin V to 2 µg/mL in Cathepsin Buffer.
  3. Mix equal volumes of the rhLipocalin-1 curve dilutions and the 2 µg/mL rhCathepsin V. Include a Cathepsin Control (in duplicate) containing Assay Buffer in place of rhLipocalin-1.
  4. Incubate mixtures at room temperature for 30 minutes.
  5. Dilute Substrate to 40 µM in Substrate Buffer.
  6. Load into a black well plate 50 µL of the incubated mixtures, and start the reaction by adding 50 µL of 40 µM Substrate.
  7. Read at excitation and emission wavelengths of 380 nm and 460 nm (top read), respectively, in kinetic mode for 5 minutes.
  8. Derive the 50 % inhibiting concentration (IC50) of rhLipocalin-1 by plotting RFU/min (or specific activity) vs. concentration with 4‑PL fitting.
  9. The specific activity for rhCathepsin V at each point may be determined using the following formula (if needed):

     Specific Activity (pmol/min/µg) =

Adjusted Vmax* (RFU/min) x Conversion Factor** (pmol/RFU)
amount of enzyme (µg)

     *Adjusted for Substrate Blank
     **Derived using calibration standard 7-amino, 4-Methyl Coumarin (Sigma, Catalog # A-9891).

Per Well:
  • rhCathepsin V: 0.05 µg
  • rhLipocalin-1: 10,000, 2500, 1000, 250, 125, 62.5, 31.25, 12.5, 3.125, and 1.5625 nM
  • Substrate: 20 µM
Reconstitution Calculator

Reconstitution Calculator

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Background: Lipocalin-1

Lipocalin-1, also known as tear prealbumin or von Ebner’s gland protein (VEGP), is encoded by the LCN1 gene (1-3). It is a member of the Lipocalin superfamily that binds many different classes of lipophylic chemicals (4). Lipocalin-1 contains three sequence motifs similar to the cystatins, a superfamily of cysteine protease inhibitors (5). In fact, it has been suggested that Lipocalin-1 is a physiological inhibitor of cysteine proteases and plays a role in the control of inflammatory processes in oral and ocular tissues (5). Recombinant Human Lipocalin-1 corresponds to the mature and secreted protein. It is a weak inhibitor of cysteine proteases such as cathepsin V, which is similar to recombinant human Cystatin S (Catalog # 1296-PI).

  1. Redl, B. et al. (1992) J. Biol. Chem. 267:20282.
  2. Blaker, M. et al. (1993) Biochim. Biophys. Acta 1172:131.
  3. Lassagne, H. and A.M. Gachon (1993) Exp. Eye Res. 56:605.
  4. Redl, B. et al. (2000) Biochim. Biophys. Acta 1482:241.
  5. van’t Hof, W. et al. (1997) J. Biol. Chem. 272:1837.
Entrez Gene IDs
3933 (Human)
Alternate Names
LCN1; lipocalin 1 (tear prealbumin); lipocalin 1-like 2; Lipocalin1; Lipocalin-1; MGC71975; PMFA; Tear lipocalin; Tear Prealbumin; TLC; TPVon Ebner gland protein; VEG protein; VEGP; VEGPlipocalin 1 (protein migrating faster than albumin, tear prealbumin)

Citation for Recombinant Human Lipocalin-1 Protein, CF

R&D Systems personnel manually curate a database that contains references using R&D Systems products. The data collected includes not only links to publications in PubMed, but also provides information about sample types, species, and experimental conditions.

1 Citation: Showing 1 - 1

  1. Method development for quantification of five tear proteins using selected reaction monitoring (SRM) mass spectrometry.
    Authors: Masoudi S, Zhong L, Raftery M, Stapleton F, Willcox M
    Invest Ophthalmol Vis Sci, 2014;55(2):767-75.
    Species: N/A
    Sample Types: N/A
    Applications: Mass Spectrometry


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