It was discovered that a fraction of membrane proteins can b

It was discovered that a fraction of membrane proteins can be removed by immersing a membrane in an aqueous salt solution, whereas the remaining fraction of proteins can only be removed by immersing the membrane in a detergen solution or organic solvent which dissolves lipids.

Which fraction contains the peripheral proteins and which fraction contains the integral proteins and why? What does this experiment say about the way peripheral and integral proteins are bound to membranes?

Solution

Plasma membrane bi layer made with different types of lipids like phospholipids, glyco lipids, spingo lipids and cholestrol, which are hydrophobic in nature. In addition to the lipids, proteins also associated with lipid bilayer to aid membrane transport. Mainly 2 types of proteins are associated with membrane. Those are external proteins - These are hydrophilic proteins which are distributed outer leaflet and inner leaflet of the membrane but not inserted in to the bilayer. Internal or integral proteins: These are hydrophobic or amphi philic proteins which are distributed with in the bilayer or spanning from outer surface of leaflet to inner leaflet through lipid bi layer.

As aqueous salt solution is hydrophilic, external proteins dissolved in it and seperate.

As detergent is amphiphilic trans membrane proteins are removed and organic solvent is hydrophobic, internal proteins are removed.

Like dissolve in like