Protease Quench, EDTA-free protease inhibitor cocktail tablets

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12th April 2021


Protease Quench, EDTA-free tablets are specifically designed to protect isolated proteins by inhibition of serine proteases, cysteine proteases and aminopeptidases during extractions from animal and plant tissues or cells, yeast and bacteria. In order to maintain stability and the function of metal-dependant proteins, these tablets do not contain EDTA. Protease Quench, EDTA-free tablets are a mixture of both irreversible and reversible protease inhibitors. Aspartic and metallo proteases are not inhibited with the exception of aminopeptidases. The affinity purification of Poly-His tagged fusion proteins via immobilized metal ion affinity chromatography (IMAC) is also facilitated without dialysis.

20 Protease Quench, EDTA-free Protease Inhibitor Cocktail Tablets are supplied in a glass vial and each tablet is sufficient for a 50ml extraction solution.


Protease Quench, EDTA-free tablets can be directly dissolved in the extraction medium and one tablet should be sufficient for the inhibition of the existing proteolytic activity in 50 ml. If very high proteolytic activity is shown then one tablet should be used for every 25ml of extraction buffer.

If working with smaller volumes then a stock solution at 50x concentration can be created by dissolving one Protease Quench, EDTA-free tablet in 1 ml redist. H2O.

Additional information

A 50x stock solution of one Protease Quench, EDTA-free tablet has an absorption of 0.35 at 280 nm. The inhibitory activity of each lot is tested with exactly defined trypsin and papain assays at 37°C. The detection is performed with a universal protease substrate: resorufinlabeled casein. Typically the proteolytic activity is inhibited by 90% after one hour.

Store dry at +2 to +8°C. Do not use after expiration date. Stock solutions are stable for 1–2 weeks if stored at +2 to +8°C.


For the use of IMAC, EDTA-free inhibitor cocktail tablets are ideal for the of IMAC where interference of EDTA can hamper this technique. Protease Quench, EDTA-free tablets are also preferentially used in the isolation process of Poly-His tagged fusion proteins and can be applied to stabilize those extracts where the stability or activity of metal-containing proteins should not be effected. Protease Quench, EDTA-free tablets efficiently inhibit serine and cysteine proteases in a broad range but no metallo-proteases with exception of aminopeptidases. Occasionally, aspartic proteases (“acid proteases“) can interfere in isolations from animal tissues or bacterial extracts (1). These proteases, however, exhibit pronounced activities only at low pH values. If extraction or single isolation steps have to be performed at this pH range then addition of Pepstatin A is recommended to inhibit aspartic protease activity. If protection of proteins from both proteases and phosphatases is necessary then combine Protease Quench, EDTA-free tablets with our Phosphatase Inhibitor Cocktail Kit.

1 North, M.J. (1969) in: Proteolytic Enzymes – A Practical Approach (Beynon, P.J. & Bond, J.S. eds.),


20 tablets ‐ £340.00


This product is limited for sale only in the UK and ROI.


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