Protein folding

Article By:

Bondos, Sarah Department of Biochemistry and Cell Biology, Rice University, Houston, Texas.

Matthews, Kathleen Department of Biochemistry and Cell Biology, Rice University, Houston, Texas.

Last reviewed:September 2021

DOI:https://doi.org/10.1036/1097-8542.801070

The process by which a long, flexible, unbranched chain of amino acids (the unfolded state of a protein) spontaneously changes shape to form a stable three-dimensional conformation (the native or folded state). Protein folding is a major functional operation by which chains of amino acids (polypeptides) fold into biologically active protein forms. This specific folding process is required for the protein's biological function. The sequential arrangement of amino acids is encoded by the genetic material—that is, deoxyribonucleic acid (DNA) [Fig. 1]. The 20 most frequently used amino acids have a region in common that forms the covalent peptide bonds in the chain, termed the backbone, and a region that is chemically distinct, identified as the side chain. Amino acid side chains vary in size and shape, as well as the propensity to interact with water, oil, and ions. As a result, the side chains are differentially able to participate in noncovalent chemical bonds (hydrophobic interactions, electrostatic interactions, and hydrogen bonds) with each other and with the solvent. In addition, the amino acid cysteine can form covalent disulfide bonds with other cysteines. Together, this chemical interaction code determines the network of bonds that drives protein folding, stabilizes the native structure, and mediates protein function for any given sequence of amino acids. See also: Amino acid; Biochemistry; Bioorganic chemistry; Deoxyribonucleic acid (DNA); Peptide; Protein

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