Question

Compare and contrast SDS-PAGE and Native-PAGE. Discuss the chemical and mechanistic similarities and differences between the two. Discuss why a scientist would prefer one method over the other.

Answer 1

Native-PAGE:

Native-Page is a sort of Polyacrylamide gel electrophoresis (PAGE) technique which is used for separation of biological macromolecules (that includes such as proteins and nucleic acid) in their native form. Macromolecules which is present in their native state preserve the highest order structure and the seperation is based on their electrophoretic mobility which will depends on many factors such as length, conformation and charge on the molecule.

This technique requires preparation of gel of polyacrylamide. After the application of this gel sample electricity is applied over the gel due to which positively charged biomolecules move towards negative electrode and vice versa. Small molecules tends to move faster than bigger molecules. After analysis is complete , visualization of sample is done using suitable stain. Molecular weight of biomolecules can also be determined by comparing with suitable markers.

SDS-PAGE:

SDS-PAGE is a sort of Polyacrylamide gel electrophoresis (PAGE) technique which is primarily used for separation of proteins and is carried out in presence of denaturing agent SDS (sodium dodecyl sulfate). SDS uses anionic detergent which changes proteins from native form to linear form.

SDS-PAGE is carried out quite similar to that of native-PAGE. Sample is prepared in presence of SDS so that native structure is broken.

Advantages of SDS PAGE=

1.migration is directly proportional to the molecular weight

2.highly selective test,separates whose error is 2% difference in mass

3.require very small amount of samples

4.it has stable chemically cross linked gel