Product Specifications for Recombinant Human Cystatin D Protein, CF
Mouse myeloma cell line, NS0-derived human Cystatin D protein Thr29-Val142, with a C-terminal 10-His tag
>95%, by SDS-PAGE under reducing conditions and visualized by silver stain
<1.0 EU per 1 μg of the protein by the LAL method.
N-terminal sequence Analysis
Predicted Molecular Mass
15 kDa, reducing conditions
Measured by its ability to inhibit papain cleavage of a fluorogenic peptide substrate Z-FR-AMC (Catalog # ES009). The IC50 value is <8 nM, under the described conditions.
Formulation, Preparation and Storage
What does CF mean?
CF stands for Carrier Free (CF). We typically add Bovine Serum Albumin (BSA) as a carrier protein to our
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
Lyophilized from a 0.2 μm filtered solution in MES and NaCl.
Reconstitute at 100 μg/mL in sterile 50 mM Tris, pH 7.0.
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 reconstitution.
Background: Cystatin D
Cystatin D is a member of family 2 of the cystatin superfamily (1). In contrast to other members of family 2, Cystatin D has restricted tissue distribution and has been found only in saliva and tears. Two allelic variants (Arg46 and Cys46) are known in the human protein and they are not significantly different in their inhibitory activity against papain and cathepsins B, H, L and S (2). Recombinant Human Cystatin D corresponds to the Arg46 variant. The functions of Cystatin D are largely unknown. However, Cystatin D has been shown to inhibit coronavirus replication at its physiological concentration (0.12‑1.9 μM) and has been suggested to play a protective role against proteases present in the oral cavity (3).
Freije, J.P. et al. (1993) J. Biol. Chem. 268:15737.
Balbin, M. et al. (1994) J. Biol. Chem. 269:23156.
Collins, A.R. and A. Grubb (1998) Oral Microbiol. Immunol. 13:59.
Which Brands are Currently Available on bio‑techne.com? R&D Systems, Tocris Bioscience and ProteinSimple branded products are available to purchase through bio‑techne.com. ProteinSimple branded instruments are available to quote. ACD branded products will be available on bio‑techne.com in the near future. Novus Biologicals branded products are not currently available on bio‑techne.com and can be found at novusbio.com.
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