Question

Sketch a membrane contain the lipid bilayer, peripheral membrane proteins, and integral membrane proteins. Label the lipid bilayer, peripheral membrane protein, an integral membrane protein. Name the types of intermolecular forces that hold peripheral and integral membrane proteins to the membrane and name the reagents that can be used to remove each type of membrane protein from association with the membrane.

Answer 1

Intrinsic membrane proteins are completely embedded inside the membrane and therefore can only be isolated by completely destroying the structure of plasma membrane. It is possible by the use of detergents.

Peripheral membrane protein are present towards the Periphery of the membrane and can be isolated by mild treatment like use of high salt concentration on change in pH.

Intrinsic proteins completely span the lipid bilayer. This is because they can show both hydrophilic and hydrophobic interactions. The core of the membrane is made up of fatty acids which are hydrophobic in nature. Intrinsic membrane proteins show hydrophobic interactions with these fatty acids. The extracellular and intracellular surface of the membrane is aqueous, therefore intrinsic membrane protein show hydrophilic interaction with these surfaces.

Extrinsic membrane proteins are present towards the extracellular surface of the membrane and therefore show hydrophilic interaction with the aqueous phase. The part of the extrinsic membrane protein which is embedded inside the membrane shows hydrophobic interaction with fatty acids.

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