Novex® Sharp Pre-stained Protein Standard From Invitrogen

Novex® Sharp Pre-stained Protein Standard from Invitrogen (catalog number LC5800) for SDS-PAGE allows visualization of protein molecular weight ranges during electrophoresis. According to the manufacturer, it can also be used to evaluate Western transfer efficiency. I have found that the Novex Sharp Protein Standard provides clear visualization of a broad range of molecular weight bands when used in pre-cast NuPAGE gels also obtained from Invitrogen. The protein standard is one of many new products that Invitrogen now offers for gel electrophoresis. You may obtain a variety of pre-cast gels, buffer, protein stains, standards and mini/midi-gel equipment, all of which work well together in my experience, at www.invitrogen.com/proteomics.

The protein standard consists of 12 pre-stained protein bands that cover the range of 3.5-260 kDa when used in electrophoresis. The bands are spaced at convenient kDa weights: 260, 160, 110, 80, 60, 50, 40, 30, 20, 15, 10, and 3.5. I have worked with antibodies, at a weight of about 150 kDa and also smaller proteins around 30 kDa, so this standard works for large variety of protein sizes. The protein standard is compatible with NuPAGE, NOVEX, Tris-Glycine, and Tricine Gels. The standard is supplied in a ready-to-use format in 2-250 µl tubes. There is no heating or adding a reducing agent. All you do is thaw the ladder to room temperature and vortex or mix gently. The gel loading volumes suggested are very specific: between 5-14 µl depending on whether you are using a 1.0 or 1.5 mm thick mini-gel or a midi gel. Blotting requires even less, 2.5 – 5 µl. It can be stored for 12 months at –20°C.

The advantage of using Novex Sharp Protein Standard with these pre-cast gels is that I can count on a crisp clear standard. The other advantage is the large span of weight ranges with some very closely spaced bands; there is no need to use a second marker for more precise visualization of molecular weight.

My experience with Novex Sharp Protein Standard has been good. However, I have not used this standard in any other gel besides the Novagen pre-cast gels produced by the manufacturer. It does cover a wide range of molecular weight and has provided consistently clear visualization. The bands are closely spaced for easy molecular weight determination.