Just as the dye adds weight, or bulk to the protein bands, distorting their exact molecular size, the bulk from the coats your dogs are wearing might also distort their shape and size. Remember the white dog analogy where your white dogs are all wearing different colored coats – coats that represent a prestained ladder. The cool thing about this is that even before the gel has completely run and then is further stained with a gel staining dye – Coomassie as in most cases – the ladder bands can be visualized by the experimenter.Įach band represents a molecular weight which is a combination of the molecular weights of the corresponding polypeptide and the associated dye. What this means is that before even loading the ladders into the gel for electrophoresis, these ladders are previously stained and ready to go.ĭuring electrophoresis, the polypeptides of the ladder show up in the gel as distinctly colored bands. In a prestained protein ladder, each of these bands, or polypeptides, are already stained with a dye. These polypeptides get resolved during electrophoresis as separate bands - based on their molecular weights. Protein ladders are composed of a series of bands, which are highly purified polypeptides of different well-defined sizes. In this article we will answer the following question – what is the difference between an unstained and a prestained protein ladder? In addition to this, we will take you through the advantages of prestained and unstained protein ladders, and how you can figure out which one is best for you.Īdvantages of using a prestained protein ladder:Īdvantages of using an unstained protein ladder: Visualization in the membrane prior to Western BlotĬan track how much electrophoresis took placeĬan track gel-to-membrane transfer for Western Blot Comparison of prestained versus unstained protein ladder.ĭifferent sized polypeptides, each tagged with a colored dye.ĭifferent sized polypetides – Not tagged with dyes. Table 1 below highlights the differences, advantages and disadvantages of prestained versus unstained protein ladders. This idea would be similar to staining the gel with Coomassie after you’ve done gel electrophoresis. So, you cannot discern them readily, until you catch up to them. Now, comparing this analogy with an unstained ladder, it would be as if you let your dogs out without any colorful coats – or dye. The dogs represent the polypeptides, the stains are the differently colored garments. The individually colored coats help you track your dogs from a distance – the color of the cloth prevents you from losing sight of them even against the background of the snow.įurther, because each dog was assigned his or her own individually colored coat, you know exactly which dog is which. But it’s wintertime, and the field is snow covered.Īs your dogs run off further and further, not only will it be hard to see them, but it’s going to be hard to see how far away each one is from you.īut what if you put different colored coats on each dog? And you let your dogs out into a big field to run around. Imagine you have a few dogs, all are white. Prestained ladders are prestained with dyes for better visualization and tracking during electrophoresis.Ī helpful way to understand the difference between unstained and prestained protein ladders is to use an analogy. The difference between an unstained protein ladder and a prestained protein ladder is that unstained ladders require additional staining post electrophoresis. However, if you're wanting to know what the difference is between the two, you've come to the right place. There are two categories of commercially available protein ladders, unstained protein ladders and prestained protein ladders.
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