7.7: Summary of protein structure levels
- Understand the structure levels of proteins.
The summary of protein structural levels is illustrated in Figure \(\PageIndex{1}\) and described in a video. The protein structure in summary form is the following.
- The primary structure is the sequence of amino acids in a polypeptide chain.
- The secondary structure is the organized sections of the polypeptide chain, e.g., \(\alpha\) helix and \(\beta\) pleated sheets.
- The tertiary structure is the overall folded 3D structure of the entire polypeptide chain, held by disulfide linkages, salt bridges, hydrogen bonding, and hydrophobic interactions.
- Quaternary structure is the association of more than one polypeptide chain (subunit) held together by the same type of interactions holding a subunit's tertiary structure.