Question

Explain why SDS-PAGE would not have allowed us to tell the difference between HbA and HbS easily on a gel.

Answer 1

The molecular weight could be estimated with SDS PAGE. Since the mobility of a substance in a gel is influenced by both charge and size, in SDS PAGE samples are treated in order to have a uniform charge, so electrophoretic mobility in SDS PAGE depends mainly on size. SDS PAGE is carried out in the presence of an anionic detergent sodium dodecyl sulfate (SDS) and a reducing agent mercaptoethanol (BME). SDS disrupts the secondary, tertiary and quaternary structure of the protein to produce a linear polypeptide chain coated with negatively charged SDS molecules. BME contributes with protein denaturation by reducing all disulfide bonds. so we can say that the structure gets disturbed so we cannot tell the difference between both Hb molecuoles