BRAINCAKEDisulfide Bridges
A disulfide bridge is a covalent bond between two sulfur atoms (S–S) in a protein. It forms between the R groups of two cysteine amino acids, which each contain a thiol group (–SH).
When two cysteines are brought close together by the folding of the chain, their –SH groups react. The two hydrogen atoms are removed (an oxidation reaction) and the two sulfur atoms bond together:
–SH + HS– → –S–S– + 2H
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Key terms in this lesson
- tertiary structure
- The overall three-dimensional shape formed by further folding of a polypeptide chain, held by bonds between R groups.
- quaternary structure
- The structure formed when two or more polypeptide chains are held together to make one functional protein.
More in Biological Molecules
- Unit Membrane
- Test for Lipids
- Amino-acids
- Hydrogen Bonding
- Ionic Bonds
- Protein Structure
- Globular Proteins
- Fibrous Proteins
All 25 lessons in Biological Molecules · All Edexcel AS-level Biology topics