Secondary structure

Definition

Secondary structure refers to the local folded structures that form within a polypeptide due to interactions between atoms of the backbone. The most common types are alpha helices and beta sheets.

5 Must Know Facts For Your Next Test

1. Secondary structures are stabilized by hydrogen bonds between the amide hydrogen and carbonyl oxygen atoms in the peptide backbone.
2. Alpha helices are right-handed coils where each turn is stabilized by hydrogen bonds between every fourth amino acid.
3. Beta sheets consist of beta strands connected laterally by at least two or three backbone hydrogen bonds, forming a pleated sheet appearance.
4. Secondary structure elements often serve as building blocks for the overall three-dimensional conformation of proteins (tertiary structure).
5. Disruptions in secondary structure can lead to loss of protein function and are implicated in various diseases, such as Alzheimer's.

Review Questions

• What type of bonding stabilizes the secondary structure of proteins?
• Describe the main differences between alpha helices and beta sheets.
• Why is secondary structure important for protein function?

Related terms

Primary Structure:

The sequence of amino acids in a polypeptide chain.

Tertiary Structure:

The overall three-dimensional shape of a single polypeptide chain.

Quaternary Structure:

The arrangement and interaction of multiple polypeptide chains in a multi-subunit complex.