Question

o assist in completing this question, you may reference the Animated Technique Video - Two-dimensional Electrophoresis. What are the roles of sodium dodecyl sulfate (SDS) in two‑dimensional electrophoresis?

Answer 1

Answer:

Sodium dodecyl sulfate (SDS) unfold the protein into simplier pieces and  makes protein negatively charged.

Explanation:

Two-dimensional (2D) electrophoresis is gel electrophoresis used for protein separation from protein mixture. Similar to other electrophoresis, this 2D electrophoresis uses different pH gradient which is applied on the gel so one end of the gel will be more positive than the other. It uses two dimensions for protein separation. In first dimension proteins are separated according to their isoelectric point (no need for protein to be charged here to be separated). Second dimension separates protein according to their mass. But first of all, protein needs to be unfolded, converted to simplier pieces. For this purposes, the substance called sodium dodecyl sulfate (SDS) is used. Once unfolded, proteins are binding to SDS which is negatively charged, so the proteins become negatively charged as well. This negativity allows proteins to be separated by second dimension. These will follow more positive charge within the gel. A protein binds a number of SDS molecules proportional to the protein's length. Since a protein's length is proportional to its mass, this is equivalent to saying that it attaches a number of SDS molecules roughly proportional to the protein's mass.