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Summary of Protein Structure definitions

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  • Primary Structure

    Linear sequence of amino acids in a protein, held together by peptide bonds, determining the protein’s unique identity.
  • Secondary Structure

    Spatial arrangement of the polypeptide chain into alpha helices or beta pleated sheets, stabilized by hydrogen bonds.
  • Tertiary Structure

    Overall three-dimensional shape of a folded polypeptide, maintained by various interactions and one covalent bond.
  • Quaternary Structure

    Complex assembly formed by the association of two or more polypeptide subunits, stabilized by multiple interactions.
  • Amino Acid

    Basic building block of proteins, each with a unique side chain, linked together to form polypeptide chains.
  • Peptide Bond

    Covalent linkage connecting amino acids in a protein’s primary structure, forming the backbone of the chain.
  • Alpha Helix

    Coiled configuration of a polypeptide chain, stabilized by hydrogen bonds, common in secondary structure.
  • Beta Pleated Sheet

    Sheet-like arrangement of polypeptide chains, stabilized by hydrogen bonds, contributing to secondary structure.
  • Hydrogen Bond

    Weak interaction between backbone atoms, crucial for stabilizing secondary, tertiary, and quaternary structures.
  • Hydrophobic Interaction

    Non-covalent force causing nonpolar side chains to cluster inside the protein, influencing tertiary structure.
  • Hydrophilic Interaction

    Non-covalent force causing polar side chains to orient toward the aqueous environment, affecting protein folding.
  • Salt Bridge

    Electrostatic attraction between oppositely charged side chains, contributing to protein stability.
  • Disulfide Bridge

    Covalent bond formed between sulfur atoms of cysteine residues, providing extra stability to protein structure.
  • Polypeptide Chain

    Linear sequence of amino acids linked by peptide bonds, forming the backbone of protein structure.
  • Subunit

    Individual polypeptide chain that associates with others to form a functional protein in quaternary structure.