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7.7: Summary of protein structure levels

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    Learning Objectives
    • 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.

    1. The primary structure is the sequence of amino acids in a polypeptide chain.
    2. The secondary structure is the organized sections of the polypeptide chain, e.g., \(\alpha\) helix and \(\beta\) pleated sheets.
    3. 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.
    4. 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.
    Figure \(\PageIndex{1}\): Illustration of primary, secondary, tertiary, and quaternary structure levels of proteins (left) and the video on What is a protein from RCSBProteinDataBank (right). (Copyright; Left: LadyofHats, Public domain, via Wikimedia Commons, right: )

    This page titled 7.7: Summary of protein structure levels is shared under a Public Domain license and was authored, remixed, and/or curated by Muhammad Arif Malik.