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18.6: Protein Structure- An Overview and Primary Protein Structure

  • Page ID
    86629
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    Learning Objectives
    • Describe primary protein structure.
    • Explain how sequence can affect function.

    Each of the thousands of naturally occurring proteins has its own characteristic amino acid composition and sequence that result in a unique three-dimensional shape. Since the 1950s, scientists have determined the amino acid sequences and three-dimensional conformation of numerous proteins and thus obtained important clues on how each protein performs its specific function in the body.

    Levels of Protein Structure

    The structure of proteins is generally described as having four organizational levels. The first of these is the primary structure, which is the number and sequence of amino acids in a protein’s polypeptide chain or chains, beginning with the free amino group and maintained by the peptide bonds connecting each amino acid to the next. The primary structure of insulin, composed of 51 amino acids, is shown in Figure \(\PageIndex{1}\).

    Chain A has 21 amino acids and Chain B has 30 amino acids.
    Figure \(\PageIndex{1}\): Primary Structure of Human Insulin. Human insulin, whose amino acid sequence is shown here, is a hormone that is required for the proper metabolism of glucose. (CC BY-SA-NC 3.0; anonymous)

    18.6: Protein Structure- An Overview and Primary Protein Structure is shared under a CC BY-NC-SA 3.0 license and was authored, remixed, and/or curated by LibreTexts.

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