Question

In an$\alpha$helix, how does hydrogen bonding occur between the amino acids in the polypeptide chain?

Short answer

In the $\alpha$-hellx, hydrogen bonds form between the carbonyl oxygen atom and amino hydrogen atom of the fourth amino acid in the sequence. So, hydrogen bonding occurs between the amino acids in that polypeptide chain.

Step-by-step solution

Introduction 

Secondary structure is the regular, local structure of the protein backbone that is stabilised by amide group intramolecular and sometimes intermolecular hydrogen bonding.

Given information

Alpha $\left(\alpha \right)$-helix is a secondary level of protein structure, in which hydrogen bonds connect the $\mathrm{NH}$of one peptide bond with the $\mathrm{C}=\mathrm{O}$of another peptide bond in that chain.

Later this peptide bond in the chain to form a coiled or corkscrew structure (shown below).

Given information 

The protein structure of $\alpha$-helix is shown below:

Explanation 

The protein structure of $\alpha$-helix is shown below:

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In the $\alpha$-hellx hydrogen bonds torm between the carbonyl oxygen atom and amino hydrogen atom of the fourth amino acid in the sequence. So, hydrogen bonding occurs between the amino acids in that polypeptide chain.