Discussion
Sodium Dodecyl Sulphate (SDS) is used while separating proteins by polyacrylamide gel electrophoresis because :
Answer: B
SDS is used because it binds to proteins and confers a uniform negative charge density, so they move in the gel according to size.
Sodium dodecyl sulphate is an anionic detergent. It unfolds polypeptides and coats them at a roughly constant ratio of about 1.4 g of SDS per gram of protein. The protein's own charge is swamped, every chain carries a similar charge per unit length, and migration through the polyacrylamide sieve then depends almost only on molecular mass.
SDS does solubilise proteins, but that alone would not make separation by mass possible, so the first option misses the point. It is not used to change the buffer's surface tension, and far from stabilising proteins it denatures them.
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