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Thermo Scientific™ Pierce™ Protease Assay Kits

Determine total protease activity in biological samples via fluorescent or colorimetric detection by measuring digestion of labeled casein substrate.

Brand:  Thermo Scientific™ 23263

Code : PN

Additional Details : Weight : 0.10000kg Transport : UN number : 2924 Chem class : 3 Pack group : II

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Product Code. 10551194

  • £328.92 / 1 set

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These Colorimetric and Fluorescent Protease Assay Kits comprise two different methods for measuring total protease activity in biological samples. Both kits can be used to assess the progress of protease purification procedures or to quantify protease contamination in protein samples. The kits use succinylated or fluorescein-tagged casein as a protease substrate. Proteolysis of the substrate results in peptides whose amino groups or altered fluorescence properties enable detection in the respective kits. Protease activity is quantified by comparison to trypsin standard included in each 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

The Colorimetric Protease Assay Kit (Part No. 23263) 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.
  • 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)
The Fluorescent Protease Assay Kit (Part No. 23266) 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.
  • 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)


Modified casein, trypsin standard and Tris-buffered saline (both kits); TNBSA solution (Part No. 23263 only)

Recommended for:

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



Pierce Colorimetric Protease Assay Kit
Borate Buffer Pack (makes 500mL), 1 pack, Succinylated Casein, 5 x 10mg, TNBSA Solution, 2mL, TPCK Trypsin Standard, 50mg
250 microplate assays using a standard plate reader (absorbance at 450nm)
Multi-component kit with TNBSA reagent
250 test kit
Safety and Handling

Safety and Handling

Product Identifier
  • Pierce Colorimetric Protease Assay Kit

Signal Word
  • Danger

Hazard Category
  • Flammable liquid Category 2
  • Acute toxicity Category 3
  • Skin corrosion/irritation Category 1 A
  • Serious eye damage/eye irritation Category 1
  • Skin sensitiser Category 1
  • Specific target organ toxicity after single exposure Category 1
  • Skin corrosion/irritation Category 2
  • Serious eye damage/eye irritation Category 2
  • Respiratory sensitiser Category 1
  • Specific target organ toxicity Category 3
  • Reproductive toxicity Category 1A

Hazard Statement
  • H225-Highly flammable liquid and vapour.
  • H302-Harmful if swallowed.
  • H311-Toxic in contact with skin.
  • H314-Causes severe skin burns and eye damage.
  • H317-May cause an allergic skin reaction.
  • H331-Toxic if inhaled.
  • H370-Causes damage to organs.
  • H319-Causes serious eye irritation.
  • H334-May cause allergy or asthma symptoms or breathing difficulties if inhaled.
  • H335-May cause respiratory irritation.
  • H360D-May damage the unborn child.

Precautionary Statement
  • P280-Wear protective gloves/protective clothing/eye protection/face protection.
  • P201-Obtain special instructions before use.
  • P202-Do not handle until all safety precautions have been read and understood.
  • P261-Avoid breathing dust/fume/gas/mist/vapours/spray.
  • P302+P352-IF ON SKIN: Wash with plenty of water/.
  • P301+P310-IF SWALLOWED: Immediately call a POISON CENTER/doctor /
  • P303+P361+P353-IF ON SKIN (or hair): Take off immediately all contaminated clothing. Rinse skin with water/ shower.
  • P305+P351+P338-IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
  • P304+P340-IF INHALED: Remove person to fresh air and keep comfortable for breathing.
  • P332+P313-If skin irritation occurs: Get medical advice/attention.
  • P337+P313-If eye irritation persists: Get medical advice/attention.
  • P308+P313-IF exposed or concerned: Get medical advice/attention.
  • P370+P378-In case of fire: Use to extinguish.

Supplemental information
  • MIXTURE LIST-Contains¬†: Methyl alcohol, Trypsin, Sodium tetraboratedecahydrate, Boric acid (H3BO3)


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