Nacalai USA - Innovations for Life Sciences

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PROKEEP Low Protein Binding Tubes

A high quality tube with superior low protein binding properties

PROKEEP is a high quality tube developed for the use of protein or peptide analysis (SDS-PAGE, HPLC, MS) as it mitigates the risk of the sample loss during experiment and preservation, and improves the signals detection.



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 PRKEEP).

With PROKEEP, elution from the tube can be avoided and better experiment result on MALDI MS analysis and Protein Chip analysis can be anticipated (See below).


PROKEEP's Protein Low Binding performance

Loss of protein and peptide when using plastic containers is caused by the following two factors.

a. Solution remained in the container after pipetting or centrifuge

b. Adsorption of protein and peptide to the plastic containers.

PROKEEP has been developed by approaching both of two factors. Watson's PROKEEP containers are incomparable in terms of achieving a low residue signal. PROKEEP's residue signal is approx. 1/20 million, which is 1/850 residue amount of other conventional hedrophilic products in the following factor (1).

No occurrance of peptide signal loss during 2 week-storage in the following factor (2).

PROKEEP 1.5 ml

Flat gate type: PROKEEP 1.5 ml


PROKEEP 2.0 ml

Hyper Micro Tube: PROKEEP 2.0 ml

(1) Residue Protein Amount

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

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 4C 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.

Ordering Information

Product Cat.No. PKG Size Price  
PROKEEP low protein binding tube 1.5 ml, Flat Bottom, Natural, Bulk PK-15C-500N 500 tubes/bag 65.00 Buy
PROKEEP low protein binding tube 2.0 ml, Natural PK-20C-500 500 tubes/bag 66.00 Buy