Which bond is responsible for holding the alpha helix of a protein in shape?
- A. peptide bonds along the backbone
- B. hydrogen bonds between backbone carbonyl and amide groups
- C. disulphide bridges between cysteines
- D. ionic bonds between side chains
Explanation
Regular hydrogen bonding between a carbonyl oxygen and an amide hydrogen four residues further along coils the chain into a helix. Peptide bonds create the chain itself rather than its coiling, and disulphide and ionic interactions belong to the tertiary level. Heat breaks the hydrogen bonds easily, which is why helices unwind on denaturation.
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