SDS and Protein Denaturation

SDS Effect on Protein Structure

• SDS (Sodium Dodecyl Sulfate) disrupts protein quaternary and tertiary structures, leading to protein denaturation.
• SDS binding causes proteins to unfold, resulting in a loss of their native conformation.

SDS-Protein Interaction

• SDS interacts with proteins through electrostatic forces, specifically binding to positively charged amino acid residues.
• The negative charge of SDS molecules interacts with the positive charge of proteins, resulting in a neutralization of the protein's charge.

Outcome of SDS Coating

• The coating of negatively charged SDS on proteins masks their native charge, resulting in a uniform negative charge.
• This uniform charge allows proteins to be separated based on their size, rather than their charge.

Electrophoresis Principle

• Electrophoresis is a separation technique based on the migration of charged particles in an electric field.
• Particles with a net charge will move towards the oppositely charged electrode.

Zone Electrophoresis

• The purpose of the stabilizing medium in zone electrophoresis is to maintain the pH and ionic strength of the system.
• The stabilizing medium helps to prevent protein-protein and protein-matrix interactions, ensuring that proteins migrate solely based on their size.

Gel Electrophoresis

• pH affects the charge and migration of proteins in gel electrophoresis.
• The buffer in gel electrophoresis maintains the pH and ionic strength of the system, ensuring that proteins migrate consistently and accurately.
• The buffer also helps to maintain the stability and integrity of the gel matrix.

Test your knowledge about the denaturation of proteins by SDS and its mechanism of disrupting noncovalent interactions. Understand how SDS alters the charge to mass ratio of proteins and enables their separation based on polypeptide chain length.