A scientist runs an SDS-PAGE experiment two separate times on a protein with a molecular weight of 200 kD. For the first experim
ent he treats the protein with SDS only and for the second experiment he treats the protein with both SDS and a reducing agent. If the first gel yields one band showing a molecular weight of 200 kD and the second run yields one band showing a molecular weight of 25 kD, the researcher should conclude that
This protein consists of 8 subunits of equal size linked by disulfide bonds
Explanation:
The sodium dodecyl sulfate-polyacrylamide gel (SDS-PAGE) is a technique widely used in molecular biology laboratories to separate proteins with molecular weights between 5 and 250 kDa. SDS is an anionic detergent used to denature proteins before electrophoresis. SDS can denature proteins by altering non-covalent bonds such as hydrogen, hydrophobic and ionic interactions, but they cannot cleave disulfide bonds. In this case, reducing agents (e.g., β-mercaptoethanol or dithiothreitol) have been used to cleave disulfide bonds.
