Question

Which of the following method to determine molecular weight uses SDS?

(a) Mass spectrometry

(b) Ultracentrifugation

(c) Gel filtration

(d) SDS-gel electrophoresis

This question was posed to me in an interview.

The query is from Determination of Molecular Weight of Enzymes topic in section Enzyme Extraction and Purification of Enzyme Technology

Answer 1

The correct answer is (d) SDS-gel electrophoresis

Best explanation: SDS is an anionic detergent whose hydrocarbon chain can be linked to hydrophobic regions in the interior part of proteins liberating SO3^– into the medium. These SDS molecules attach to single proteins and give it a negative charge. Hence when subjected to electrophoresis, all the proteins should travel together, but it doesn’t occur and the proteins will be separated based on the size.