8. The bonds/interactions which holds two antiparallel beta sheets together are

   (1) Disulphide bond
   (2) Covalent bond
   (3) Hydrogen bond
   (4) Hydrophobic interaction

How Antiparallel Beta Sheets Are Held Together

The Mechanism of Holding Antiparallel Beta Sheets Together

Proteins’ basic secondary structure, beta sheets, give them strength and stability. The orientation of the polypeptide chains determines whether these sheets are parallel or antiparallel. Protein folding and function depend on the forces that hold them together.

Hydrogen Bonds (Option 3) is the right response.

The main force holding two antiparallel beta sheets together among the options provided is hydrogen bonding because:

One strand’s carbonyl oxygen (C=O) and another strand’s amide hydrogen (N-H) combine to form hydrogen bonds.

Compared to parallel beta sheets, antiparallel beta sheets are more stable due to their stronger, more linear hydrogen bonds.

The rigid and well-organised structure necessary for protein stability is preserved in part by these bonds.

Why Other Choices Are Wrong

Option 1: Disulphide Bonds

Instead of beta sheets, these covalent connections between cysteine residues stabilise tertiary structures.

Covalent Connections (Choice 2):

Beta sheets are not held together by covalent bonds, but amino acids are held together within polypeptide chains.

Interactions That Are Hydrophobic (Option 4):

Although they don’t specifically stabilise beta sheets, hydrophobic interactions aid in protein folding.

In conclusion, beta sheets are stabilised by hydrogen bonds.

Since hydrogen bonds are the main mechanism that stabilise antiparallel beta sheets, Option 3 is the right response. Protein structure, enzyme function, protein structure, and even disease-related misfolding depend on these interactions.