2. In proteins, hydrogen bonds form as follows: Donor (D)- H—-Acceptor (A). Hydrogen bond is more favorable if the angle between D-H and A is

   (1) <90⁰
   (2) 180⁰
   (3) >180⁰
   (4) 120⁰

Optimal Hydrogen Bond Angle in Proteins

Maintaining protein structure, promoting folding, and guaranteeing appropriate biological function all depend on hydrogen bonds. These bonds are formed in a particular geometric alignment between an acceptor (A), hydrogen (H), and donor (D) atoms.

Which Hydrogen Bond Angle Is Best?

The angle between D-H and A must be as near to 180° as feasible for a hydrogen bond to be powerful and effective. The donor and acceptor will interact as best they can thanks to this linear alignment, which also maximises electrostatic attraction.

Why is the ideal angle 180 degrees?

Greater Bonding: A stronger hydrogen bond results from the optimal overlap of atomic orbitals, which is made possible by a linear orientation.

Improved Stability: When hydrogen bonds are functioning at their best, proteins retain their structural integrity.

Effective Energy Use: Compared to an angled or distorted bond, a perfectly aligned bond uses less energy to maintain.

What About Different Viewpoints?

Lower than 90° (<90°): Extremely unfavourable because of poor alignment and steric hindrance.

120°: Not ideal, but reasonably stable.

More than 180° (>180°): Not found naturally in proteins and geometrically unfeasible.

Conclusion: Proteins’ Optimal Hydrogen Bond Angle is 180

The most advantageous angle for hydrogen bonding in proteins among the options provided is 180°. It is the preferred geometric arrangement in biological molecules because it guarantees maximum bond strength, stability, and effective energy utilisation.