SDSPAGE separates proteins according to a charge b charge an

SDS-PAGE separates proteins according to?

a. charge b. charge and shape c. size and shape d. size

Solution

Choice D is correct.

Reason: SDS-PAGE is based upon the fact that when proteins are given equal charge, they will be separated on the basis of their size through the pores of the acrylamide gel. According to this techniques, the protein sample is dissolved in a buffer containing large amount of detergent SDS or sodium dodecyl sulphate which gives an equal and excessive negative charge to all the proteins. After that, the protein samples are heated to denature them and the protein gets into primary linear polypeptide structure. At this point, the samples are cooled down and resolved on SDS PAGE. Thus, the only basis of separation of the samples would be on the basis of their size. This is why a molecular weight protein ladder is resolved simultaneously with the samples.