PageRuler™ Unstained Low Range Protein Ladder
PageRuler™ Unstained Low Range Protein Ladder
Thermo Scientific™

PageRuler™ Unstained Low Range Protein Ladder

Thermo Scientific PageRuler Unstained Low Range Protein Ladder is a mixture of eight purified proteins and peptides (3.4 to 100Read more
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Catalog NumberQuantity
266322 x 250 μL
26632X48 x 250 μL
Catalog number 26632
Price (USD)
139.00
Each
Add to cart
Quantity:
2 x 250 μL
Request bulk or custom format
Price (USD)
139.00
Each
Add to cart

Thermo Scientific PageRuler Unstained Low Range Protein Ladder is a mixture of eight purified proteins and peptides (3.4 to 100 kDa) for use as size standards in peptide and small-protein gel electrophoresis. The protein ladder is supplied in a ready-to-use format for direct loading onto gels; no need to heat, reduce, or add sample buffer prior to use.

Product features

  • Reference bands—25 kDa band is stronger than the others for easy orientation
  • Tagged—the ladder proteins (except for the 5 and 3.4 kDa peptides) contains an integral Strep-tag™ II sequence and can be detected on western blots using Strep-Tactin™ conjugates

Applications

  • Accurate protein sizing on SDS-polyacrylamide gels and western blots
For Research Use Only. Not for use in diagnostic procedures.
Specifications
Number of Markers8
Product TypeProtein Ladder
Ready to LoadYes
Recommended ApplicationsTricine gels
Size Range3.4 to 100 kDa
Stain TypeUnstained
Gel CompatibilityBolt™ Bis-Tris Plus Gels, Novex™ Tricine Gels, Novex™ Tris-Glycine Gels, NuPAGE™ Bis-Tris Gels, NuPAGE™ Tris-Acetate Gels, SDS-PAGE Gels
Molecular Weight (g/mol)100, 30, 25, 20, 15, 10, 5, 3.4 kDa
Product LinePageRuler™
Quantity2 x 250 μL
Shipping ConditionApproved for shipment on Wet or Dry Ice
System TypeSDS-PAGE
Unit SizeEach
Contents & Storage
Includes two vials of 250 μL each

Storage buffer: 62.5 mM Tris-H3PO4 (pH 7.5 at 25°C), 1 mM EDTA, 2% SDS, 100 mM DTT, 1 mM NaN3, 0.01% bromophenol blue and 33% glycerol

Upon receipt, store at -20°C.

Frequently asked questions (FAQs)

The upper bands of the ladder are missing. What could be the reason?

The upper bands of the ladder may be degraded by proteases. Ladder, gel, buffer, pipettes, pipette tips, or equipment can be contaminated by proteases during usage. A general recommendation would be to avoid working with proteases in the same room. We would recommend preparing fresh solutions, cleaning the equipment, and using clean pipettes and tips. If the ladder itself is contaminated, please use a new tube of the ladder.

Find additional tips, troubleshooting help, and resources within our Protein Assays and Analysis Support Center.

Some additional bands or smears were observed on the gel when using a PageRuler unstained ladder. What may have caused this?

Additional bands can appear due to dithiothreitol (DTT) oxidation in the storage buffer. Please add newly prepared DTT solution to the final concentration of 100 mM and boil for 5 min at 95 degrees C. This should solve the issue. Addition of DTT is NOT recommended for prestained protein ladders, since too high a concentration of reducing agents can cause protein destaining.

Find additional tips, troubleshooting help, and resources within our Protein Assays and Analysis Support Center.

Do the proteins in Thermo Scientific protein ladders have a His-Tag or would otherwise react with an anti-His-Tag antibody?

No, proteins in Thermo Scientific protein ladders are not His tagged. However, non-specific interaction between the ladder proteins and primary or secondary antibodies is possible and some His-Tag detection systems, such as Thermo Scientific 6xHis Protein Tag Stain Reagent Kit, show non-specific interaction. The protein ladder bands are more readily detected when using high antibody concentrations. The non-specific cross-reactivity is difficult to predict, it often has a different pattern dependent on the antibodies used in each individual experiment. The most general way to handle this problem would be to use lower concentrations of antibodies and to use lower amount of protein ladders. It may also be useful to leave one empty well between the ladder and the sample to overcome a possible leakage of the signal to the nearby sample lane.

Find additional tips, troubleshooting help, and resources within our Protein Assays and Analysis Support Center.

Can Thermo Scientific protein ladders be detected by Strep-Tactin conjugates?

PageRuler Unstained protein ladders can be detected directly on Western blots by using Strep-Tactin conjugates or an antibody against the Strep-tag II sequence. All PageRuler and Spectra ladder proteins contain an integral Strep-tag II sequence, however the prestained ladders cannot be detected by Strep-Tactin conjugates.

Find additional tips, troubleshooting help, and resources within our Protein Assays and Analysis Support Center.

Why is non-specific binding detected after Western blot?

Protein ladder bands can sometimes be detected with chemiluminescent techniques due to non-specific interactions of ladder proteins with either primary or secondary antibodies (or with both). The ladder bands are only rarely detected by chromogenic substrates. The extremely high sensitivity of the chemiluminescent assays is needed to see the bands, so the actual degree of cross-reactivity is low. The non-specific cross-reactivity is difficult to predict, it often has a different pattern depending on the antibodies used. If antibodies recognize a linear epitope, the cross-reactivity may be due to sequence homology. If antibodies react with a denaturation-resistant conformational epitope it could be impossible to identify the exact reason for detected cross-reactivity. The most general way to handle this problem would be to use lower concentrations of antibodies.

Find additional tips, troubleshooting help, and resources within our Protein Assays and Analysis Support Center.

View all PageRuler™ Unstained Low Range Protein Ladder FAQs