Recombinant E. coli HTRA/Protease Do Protein, CF

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R&D Systems Recombinant Proteins and Enzymes
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Product Details

Recombinant E. coli HTRA/Protease Do Protein, CF Summary

Product Specifications

>90%, by SDS-PAGE under reducing conditions and visualized by silver stain
Endotoxin Level
<1.0 EU per 1 μg of the protein by the LAL method.
Measured by its ability to cleave beta -casein. Recombinant E. coli HTRA/Protease Do will cleave >95% cleavage of beta -casein, as measured under the described conditions.
E. coli-derived e. coli HTRA/Protease Do protein
Ala27-Gln474, with a C-terminal 10 His tag and ERSIGS sequence
Accession #
N-terminal Sequence
Predicted Molecular Mass
49 kDa
50 kDa, 41 kDa and 27 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 HEPES and NaCl.
Shipping The product is shipped with dry ice or equivalent. 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, -70 °C as supplied.
  • 3 months, -70 °C under sterile conditions after opening.

Assay Procedure

  • Assay Buffer: 50 mM Tris, pH 8.0
  • Recombinant E.coli HTRA/Protease Do (reHTRA) (Catalog # 1670-SE)
  • beta -Casein (Sigma, Catalog # C-6905), 1.0 mg/mL stock in 25 mM Tris, 0.15 M NaCl, pH 7.5
  • SDS-PAGE with silver staining
  1. Dilute beta -Casein to 0.4 mg/mL in Assay Buffer.
  2. Dilute reHTRA to 0.04 mg/mL in Assay Buffer.
  3. Combine 25 μL of beta -Casein and 25 μL of reHTRA in a tube. Prepare a control containing 25 μL of beta -Casein and 25 μL of Assay Buffer.
  4. Incubate the mixture for 1 hour at 45 °C.
  5. Stop the reaction by adding SDS-PAGE sample buffer.
  6. Analyze the cleavage by SDS-PAGE using silver staining to detect protein.
Per Reaction:
  • reHTRA: 0.02 mg/mL
  • beta -Casein: 0.2 mg/mL
Reconstitution Calculator

Reconstitution Calculator

The reconstitution calculator allows you to quickly calculate the volume of a reagent to reconstitute your vial. Simply enter the mass of reagent and the target concentration and the calculator will determine the rest.


Background: HTRA/Protease Do

As a heat shock protein and a serine protease, HTRA (Protease Do or the DegP protease) is indispensable for bacterial survival at temperatures above 42 °C (1). It is a periplasmic protein with a signal peptide of 26 amino acid residues. The mature protein contains two 90 amino acid PDZ domains, which start at residue 280. The serine protease activity is inhibited by diisopropyl fluorophosphate or dichloroisocoumarin. Four human proteins have been identified that are homologous to E. coli HTRA and believed to play a role in arthritis, cell growth, unfolded stress response, apoptosis, aging, and tumor progression (2).

  1. Skorko-Glonek, J. et al. (1995) J. Biol. Chem. 270:11140.
  2. Clausen, T. et al. (2002) Mol. Cell 10:443.
Long Name
High Temperature Requirement
Entrez Gene IDs
962111 (E. coli)
Alternate Names
DegP; HTRA; Protease Do


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