Question

What is the relationship between the velocity of the protein and the molecular weight? The relationship between the velocity and overall charge, and the relationship between the velocity and the surface area of protein?

Answer 1

Velocity of protein and its molecular weight are inversely proportional. Higher the molecular weight of the protein lower will be the velocity of protein or the mobility of the protein. Compact and lesser molecular weight proteins have more tendency to move faster. In SDS PAGE, the proteins are entirely negatively charged hence, they are not separated according to charge but only on the basis of size and shape. Negatively charged protein will move towards positive electrode or anode.

Lesser the surface area of the protein, higher will be its mobility. As compact protein structure or globular structure of protein will have higher velocity as compared to linear form or primary structure of same molecular weight.