What are the two common types of protein secondary structure, and how do they differ?

Key Concepts

Protein Secondary Structure

Protein secondary structure refers to the local folded structures that form within a polypeptide due to hydrogen bonding between the backbone atoms. The two most common types are alpha helices and beta sheets, which contribute to the overall stability and functionality of proteins.

Alpha Helix

An alpha helix is a right-handed coiled structure where each turn of the helix is stabilized by hydrogen bonds between the carbonyl oxygen of one amino acid and the amide hydrogen of another, four residues down the chain. This structure is characterized by its helical shape and is commonly found in many proteins.

Beta Sheet

Beta sheets are formed by linking two or more beta strands through hydrogen bonds, creating a sheet-like structure. These strands can be parallel or antiparallel, depending on the direction of the polypeptide chains, and they provide significant tensile strength to proteins, often found in fibrous proteins.