Which types of forces are present in the tertiary structure of protein?

Electrostatic, hydrogen bonds, van der Waals forces, dipole-dipole attractions and disulphide cross linkage

The correct answer is option 1. Electrostatic, hydrogen bonds, van der Waals forces, dipole-dipole attractions and disulphide cross linkage.

Let us delve into the types of forces present in the tertiary structure of proteins and how they contribute to their stability and function:

Electrostatic Interactions:

Nature: Electrostatic interactions, also known as ionic interactions, occur between charged groups on amino acid residues within a protein.

Charge Interactions: These interactions can be attractive (between opposite charges, e.g., between positively charged lysine and negatively charged aspartate) or repulsive (between like charges).

Strength: They are generally stronger than van der Waals forces but weaker than covalent bonds.

Hydrogen Bonds:

Nature: Hydrogen bonds are formed between hydrogen atoms and electronegative atoms such as oxygen or nitrogen.

Occurrence: They often occur between the hydrogen of an amino or hydroxyl group and an oxygen or nitrogen atom of another amino acid residue.

Contribution: Hydrogen bonds are crucial for maintaining specific secondary structures like alpha helices and beta sheets, and they also contribute to the overall stability of the folded protein structure.

van der Waals Forces:

Nature: Van der Waals forces are weak, short-range attractions between atoms or groups of atoms.

Mechanism: They arise from transient dipoles that occur due to fluctuations in electron density around atoms.

Contribution: Van der Waals interactions help to stabilize the packing of side chains within the protein's interior, contributing to the compactness and stability of the tertiary structure.

Dipole-Dipole Attractions:

Nature: Dipole-dipole attractions occur between polar groups that have permanent dipoles.

Contribution: They contribute to the specific orientations and interactions between polar side chains or regions of the protein, influencing its overall structure and stability.

Disulfide Cross-Linkages (Disulphide Bonds):

Nature: Disulphide bonds are covalent bonds formed between the sulfur atoms of two cysteine residues.

Formation: They form when the thiol groups \((-SH)\) of two cysteine residues undergo oxidation to form a covalent S-S bond.

Contribution: Disulphide bonds are important in stabilizing the tertiary structure of proteins, particularly in extracellular proteins or proteins secreted outside the cell where reducing conditions are not present.

Overall Function:

Stabilization: These various forces and bonds work together to stabilize the folded three-dimensional structure of proteins.

Functional Specificity: The specific arrangement of these interactions dictates the protein's function, such as enzyme catalysis, receptor binding, structural support, and transport.

Conclusion: The tertiary structure of proteins is stabilized by a combination of electrostatic interactions, hydrogen bonds, van der Waals forces, dipole-dipole attractions, and in some cases, disulphide bonds. These forces collectively ensure the proper folding and stability of proteins, which is crucial for their biological function and activity.