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PROKEEP - Protein Low Binding Tube

Manufactured by Watson's proprietary precision tooling and materials.

A high quality tube with protein low binding properties.

What are PROKEEP Protein Low Binding Tubes ?

PROKEEP is designed for protein or peptide analysis (SDS-PAGE, HPLC, MS). It mitigates the risk of sample loss and improves the signals obtained.

Our special blending plastic materials avoid problem caused by elution from the tube.

PROKEEP tubes reduce protein binding as a result of using our special blending of raw materials with low protein/peptide absorption and our technique of high precision finishing on the mold (no surface treatment on PROKEEP).



The bottom design is modified as shown in the following image:


Contamination prevention

Lock part prevents the thumb from touching the inner cap when opening and closing.

Friendly hinge for finger

Rounded and embossed cap-edge reduces irritation to the finger, and makes it easier to close the cap.

Unique shape of cap

Easy opening cap with less force. Flat cap allows marking on the top.


The volume is easily recognized with the scale for each 0.5 mL described on the tube.

Writing space

Writing space is available on the surface of tube (opposite side from the scale side).

Cat. No. Item Unit Case
PK-15C-500N PROKEEP protein low binding tube 1.5 mL,
Flat Bottom, Natural, Bulk pack
500 tubes / bag 20 bags  
PROKEEP protein low binding tube 1.5 mL,
Flat Bottom, Natural, Bulk pack
500 tubes / bag 20 bags
PK-20C-500 PROKEEP protein low binding tube 2.0 mL,
Round Bottom, Natural, Bulk pack
500 tubes / bag 20 bags  


Material: Virgin Polypropylene (autoclavable)
Centrifuge force:
PK-15C-500 / 20,000 x G (water 1.0 mL, 15 minutes)
PK-20C-500 / 7,000 x G (water 1.5 mL, 15 minutes)


PROKEEP's Protein Low Binding performance

Protein and peptide loss when using plastic containers is caused by 2 factors.
(1) Solution residue that has not been collected by pipetting and centrifuge operation.
(2) Protein and peptide bonded to the containers
Many conventional container manufacturers have focused their development on either one of the above, but at Watson we have successfully addressed both factors.
Watson's PROKEEP containers are incomparable at in terms of achieving a low residue signal. PROKEEP's residue Signal is approximately 1 / 20 mill, which is 1 / 850 residue amount of other company's hydrophilic products in factor (1). No occurrence of peptide signal loss during 2 weeks-storage in factor (2).

(1) Residue Protein Amount: Fig 1
Test Method:

FITC-BSA solution (1 µg / mL) was put in a microtube and left for 1 hour at room temperature. The fluorescence of the surface of the tube was measured and digitized after removal of the solution, and then the residual protein mass was analyzed. This method evaluates the residual amount on the surface of the tube.


The residue amount on PROKEEP low protein binding tube is extremely small, which is 1 / 20 mill of the protein added. Tubes with hydrophilic surface treatment exhibited higher residue amount due to characteristic of the treatment.

(2) Adsorption of protein and peptide to the tube: Fig 2
Test Method:

A solution(0.1%TFA, 10 µL) equivalent to 500 fmol / µL peptide mix contained in Bruker Daltonics's Peptide calibration standard(#206195) was put in a tube and kept at 4℃ for 2 weeks. Then, the peptide in the tube was collected and analized by mass spectrometer(Bruker Daltonics's Ultraflex tof/ tof).


In the case of PROKEEPs protein low binding tube, all the peaks were detected after the 2 weeks. Our competitor's low binding tubes showed a part of the peaks were undetectable and peptide loss by binding was observed (Fig 2B).

(3) Crystallization on MALDI Target Plate
Test Method:

In the crystalyzation process on a target plate, which is the indispensable process of MALDI type mass spectrometer analysis, a sample collected from another company's hydrophilic treated tube exhibited a disturbance in crystalization and it was difficult to conduct an accurate measurement, and elution of resin content was suspected(Fig. 3). PROKEEPs protein low binding tube showed equivalent performance to the tube recommended by Bruker Daltonics.

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