logo.gif (3296 bytes)Introduction to Protein Structure

Disulfide Bonds


Disulfide bonds are formed by the oxidation of thiol (-SH) groups in cysteine residues:

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Disulfide bonds occur intramolecularly (i.e within a single polypeptide chain) and intermolecularly (i.e. between two polypeptide chains). Intramolecular disulfide bonds stabilize the tertiary structures of proteins while thoise that occur intermolecularly are involved in stabilizing quartenary structure. Not all proteins contain disulfide bonds.

Shown below is a molecular model of lysozyme with the disulfide bonds shown as white rods between yellow sulfur atoms. Lysozyme has a total of four intramolecular disulfide bonds. Note that the cysteine residues involved in one disulfide bond can be far apart in the primary structure.

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Copyright 1998, 1999, 2007 by Frank R. Gorga;   Page maintained by F.R. Gorga;   Last updated: 12-Mar-2007