Question

1. How is an SDS gel formed (reagents, catalyst, and the reaction equation)?

2. What are the two parts of the SDS gel and the purpose of the two parts?

3. How do you approximate the size of the proteins in a gel?

Answer 1

(1) An SDS gel is composed of a mixture of sodium dodecyl sulfate (SDS, also known as sodium lauryl sulfate) and polyacrylamide gel.

The required equation is:

NaC₁₂H₂₅SO_{4 + (C3H5NO)n ------------------> SDS-gel}

(Sodium dedocyl sulfate) (polyacrylamide gel)

(2) SDS gel consists of two parts: sodium dedocyl sulfate and polyacrylamide gel.

SDS acts as a reducing agent and breaks disulfide bonds in tertiary structure of proteins and unfold the polypeptide chains. The polyacrylamide gel forms a mesh work of stacking and separating gels that separate proteins based on the lengths of their polypeptide chains.

(3) In SDS gel, proteins are unfolded by sodium dodecyl sulfate by breaking disulfide bonds. The polyacrylamide gel separates proteins based on the polypeptide chain length. Smaller proteins migrate faster through the gel as compared to proteins with long polypeptide chains. This helps to approximate the size of the proteins in the gel.