Thermo Scientific™

Pierce™ Fluorescent Protease Assay Kit

Catalog number:  23266

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The Thermo Scientific Pierce Fluorescent 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 includes fluorescein-labeled casein as a substrate for assessing protease activity in a sample by either fluorescence resonance energy transfer (FRET) with a standard fluorometer or fluorescence polarization (FP) with capable instrumentation. FTC-Casein is native casein that has been labeled using a large molar excess of fluorescein isothiocyanate (FITC). Fluorescence properties of this heavily-labeled, intact protein substrate change dramatically upon digestion by proteases, resulting in a measurable indication of proteolysis.

Features of the Fluorescent 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: fluorescein-labeled casein (FITC-casein); available separately as Part No. 23267
• Basis of assay: change in fluorescence resonance (FRET) or fluorescence polarization (FP)
• Measurement: instrument with fluorescein excitation and emission filters (485/538nm)

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


Assay Type: Protein Activity Assay
Detection Method: Fluorescent
For Use With (Equipment): Microplate Reader
Format: 96-well plate
Product Line: Pierce™
Product Size: 1000 tests
Substrate: Casein
Substrate Properties: Protein-Based Substrate
Substrate Type: Protease Substrate
Target Enzyme: Proteases
Technique: FRET, Fluorescence Polarization

Contents & storage

Sufficient For: 2000 microplate assays using an instrument fitted with a fluorescein filter set (ex/em 485 nm/538 nm)
• FTC-Casein, lyophilized, 2.5 mg
• TPCK Trypsin Standard, 50 mg
• TBS Buffer Pack (makes 500 mL), 1 pack

Store FTC-Casein and TPCK Trypsin at 4°C.


Manuals & protocols