Question

How are alpha helices stabilized?

Answer 1

1. The 2 major factors that stabilize the alpha helix are the intrachain Hydrogen bonding and the minimization of steric interference between the side chains.
2. An alpha helix is a kind of secondary structures adapted by proteins. Alpha helices are stabilised by hydrogen bonding. The alpha-helix (-helix), which is a right-hand-coiled or spiral conformation (helix), is a frequent motif in the secondary structure of proteins. Every backbone$\mathrm{NH}$group donates a hydrogen bond to the backbone$\mathrm{C}=\mathrm{O}$group of the amino acid.
3. Hydrogen bonds between the "hydrogen" of the amino group in the nth amino acid and the "oxygen" of the carbonyl group in the $\mathrm{n}+4^{\mathrm{th}}$ amino acid are principally responsible for the stability of such structures. Even though a single hydrogen bond has a very low bond strength, the creation of numerous hydrogen bonds stabilises the protein structure sufficiently.
4. Water soluble proteins, enzymes, antibodies, and other molecules frequently contain alpha helices. The membrane-spanning portion of transmembrane proteins contains alpha helices as well.