Thermo Scientific™

Pierce™ Colorimetric Protease Assay Kit

Catalog number:  23263

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The Thermo Scientific Pierce Colorimetric Protease Assay Kit measures total protease activity in samples, providing a means to assess the progress of protease isolation procedures or quantify protease contamination in biological samples. This kit uses fully succinylated casein as a substrate for the assay. Hydrolysis of this substrate in the presence of protease results in the release of peptide fragments with free amino-terminal groups. These peptides are reacted with trinitrobenzene sulfonic acid (TNBSA), followed by measurement of the absorbance increase that results from the formation of yellow colored TNB-peptide adducts.

Features of the Colorimetric Protease Assay Kit:

Casein substrate—measure activity of any protease that cleaves casein into peptide fragments
Trypsin standard—quantify protease activity relative to trypsin, a universally accepted reference
Sensitive—1000 times more sensitive than assays that use unmodified forms of casein
Simple and fast—test tube and microplate protocols are completed in less than one hour
Homogenous—addition steps only; no separation, transfer or stop steps required
Customizable—easily adapt time, temperature and pH to optimize sensitivity for proteases of interest

• Assess functional integrity and overall progress of protease purification
• Quantify protease contamination in protein samples
• Characterize the activity of unusual proteases compared to trypsin
• Evaluate buffer conditions for their affects on protease function and activity

Additional Specifications:
• Substrate: succinylated casein (not available separately)
• Basis of assay: detection of primary amines resulting from proteolysis
• Detection reagent: trinitrobenzene sulfonic acid (TNBSA)
• Measurement: absorbance at 450nm (plate reader or spectrophotometer)

Related Products
Pierce™ Fluorescent Protease Assay Kit
FITC-Casein for Pierce™ Fluorescent Protease Assay Kit
For Research Use Only. Not for use in diagnostic procedures.


Assay: Protein Activity Assay
Product Line: Pierce™
Substrate: Casein
Substrate Properties: Protein-Based Substrate
Target Enzyme: Proteases
Technique: Absorbance
Detection Method: Colorimetric
For Use With (Equipment): Microplate Reader
Format: 96-well plate
Substrate Type: Protease Substrate
Quantity: 250 Test Kit

Contents & storage

Sufficient For: 250 microplate assays using a standard plate reader (absorbance at 450 nm)
• Succinylated Casein, 5 x 10 mg
• TNBSA Solution, 2 mL
• TPCK Trypsin Standard, 50 mg
• Borate Buffer Pack (makes 500 mL), 1 pack

Store at 4°C.