Side-chain hydrogen bonding : a) Side chains that can form hydrogen bonds are located on the outside of a protein, where they can stabilize tertiary structure by forming hydrogen bonds with water.
b) Two cysteine residues can form hydrogen bonds.
c) Side chains connect distant parts of a polypeptide chain and introduce loops into the chain.
d) Threonine and glutamine can form hydrogen bonds.
e) Hydrogen bonds stabilize quaternary protein structure by holding together several protein strands.

a) Side chains that can form hydrogen bonds are located on the outside of a protein, where they can stabilize tertiary structure by forming hydrogen bonds with water.

Explanation:

A hydrogen bond occurs between a hydrogen atom and four other elements. The side chain hydrogen bonds are resulted from the tertiary arrangement of structural components of the proteins.

The side chain hydrogen bond are present at the outside of the protein at places where the water forming the hydrogen bond can stabilize the tertiary structure.

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