New England Biolabs, P7718S, Blue Prestained Protein Standard, Broad Range (11–250 kDa)

The Blue Prestained Protein Standard, Broad Range is a mixture of highly pure, recombinant, prestained proteins, covalently coupled with a blue chromophore, that resolves into 11 sharp bands when electrophoresed. Related Categories Protein Standards,, Markers & Ladders,, Protein Standards Applications Protein Standards,, Protein Analysis Tools Specification Storage Buffer 62.5 mM Tris-phosphate 1 mM EDTA 2% SDS 10 mM DTT 1 mM NaN3 33% Glycerol pH 7.5 @ -20°C FAQ Q: How does the new Blue Prestained Protein Standard, Broad Range differ from NEB’s previous Blue Prestained Protein Standard? A: The new Blue Prestained Protein Standard (NEB #P7718) can be used as a direct replacement of the previous Blue Prestained Protein Standard (NEB #P7706). The proteins used in the new Blue Prestained Protein Standard are different than those used in the previous Blue Prestained Protein Standard, thus it is important to note that the apparent molecular weights will be slightly different. The new Blue Prestained Protein Standard contains 11 proteins ranging in molecular weight from 11 – 250 kDa; whereas, the previous Blue Prestained Protein Standard contained 11 proteins ranging in molecular weight from 11 – 190 kDa. Q: What is the protein concentration of the proteins used in the Blue Prestained Protein Standard, Broad Range? A: The overall protein concentration of the Blue Prestained Protein Standard, Broad Range is approximately 2.5 mg/ml. However, this is merely an estimate. We do not recommend using this or any protein standard as a tool for precise quantitation of protein concentration. These products are meant to estimate protein molecular weight. Q: What volume is supplied in a small pack and a large pack of NEB’s Protein Standards? A: Small packs of NEB’s Protein Standards (NEB #P7717, #P7718, #P7719) contain 0.45 ml, which is equivalent to 150 gel lanes at the recommended 3 µl mini-gel load volume. Large packs contain 2.25 ml, which is equivalent to 750 gel lanes at the recommended 3 µl mini-gel load volume. Q: I notice that the molecular weights I am observing are slightly different than those reported. Can you explain? A: Apparent molecular weight values for the Blue Prestained Protein Standard, Broad Range can be different when run on different gel types and percentages. The reason for this disparity is due to the different formulations of various gels (buffering agents, ionic strength and pH). These differences are a result of the covalent attachment of dye to the proteins used in the standard. These molecules can carry a charge, changing the ability of the SDS to bind to the protein, as well as contributing to the protein’s overall charge. This altered charge will alter its mobility within the gel. We have analyzed NEB’s Blue Prestained Protein Standard, Broad Range using a variety of commonly-used gel types. The results are shown below: Q: I accidentally left my Protein Standard out at room temperature for a number of days. Is it still okay to use? A: Stability testing has shown that NEB’s Protein Standards will remain stable for up to 2 weeks at room temperature (25°C) and for up to 1 year at 4°C. We do not, however, recommend storing your Protein Standard at anything other than optimal storage temperature, which is -20°C, for a guaranteed shelf life of 2 years.