Consider a mixture of four proteins with various molecular weights. A histone molecule weighs 15 kDa, a p53 molecule weighs 53 kDa, an actin molecule weighs 42 kDa, and an IgG molecule weighs 150 kDa. Arrange the molecules in order of their elution from a gel filtration column.

IgG molecule

p53 molecule

actin molecule

histone molecule

Explanation:

Gel filtration chromatography is used to separate proteins the based on their weight. The column is filled with a gel matrix (e.g. sephadex) that the larger molecules are excluded from, and smaller molecules can penetrate into. Thus the larger molecules interact less and elute faster.

The larger molecule in a gel filtration column elute first, so for the mixture of proteins in this example, the proteins will elute in this order:

IgG molecule - 150 kDa

p53 molecule - 53 kDa

actin molecule - 42 kDa

histone molecule -  15 kDa

Immunoglobulin G (IgG) (150 kDa) comes out first, followed by molecule p53 (53 kDa), followed by Actin (42 kDa), and the Histone molecule (15 kDa).

Explanation:

Gel filtration (also known as Size Exclusion Chromatography) is a separation technique that elutes molecules through a particular resin based on difference in their molecular sizes.

This separation methods in majorly used for separating proteins using a polysaccharide resin. The protein sample is layered on the resin and then, an elution buffer is run through the column which allows the different molecules fizzle through the resin one after the other.

In Gel filtration, larger molecules elute first before smaller molecules.

This is because the small molecules enter the pore of the polysaccharide resin while larger molecules are unable to enter and thereby pass through the side of the resin molecules.

For this question, the protein molecules elute in the following order

IgG (150kDa) → Molecule p53 (53 kDa) → Actin (42 kDa) → Histone (15 kDa)

Hence, Immunoglobulin G (IgG) comes out first followed by p53 followed by Actin, and the Histome molecule.