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Peptide Bonds, Disulfide Bonds and Properties of Small Peptides

  1. Hiram F Gilbert

Published Online: 15 SEP 2010

DOI: 10.1002/9780470015902.a0001328.pub2

eLS

eLS

How to Cite

Gilbert, H. F. 2010. Peptide Bonds, Disulfide Bonds and Properties of Small Peptides. eLS. .

Author Information

  1. Baylor College of Medicine, Houston, Texas, USA

Publication History

  1. Published Online: 15 SEP 2010

Abstract

The peptide bond links amino acids into head-to-tail polymers in proteins as peptides. Chemically, the peptide bond is an amide with restricted rotation about the carbon–nitrogen bond. This restricted rotation combined with free rotation around the alpha carbon of the linked amino acids define the three-dimensional structure of all proteins. The structure of a peptide or protein can be further stabilised by introducing disulfide crosslinks, a chemical oxidation between two sulfhydryl groups of the amino acid cysteine stabilise specific conformations of peptides and proteins. Small peptides, which often function biologically as hormones or other signalling molecules can also be useful model systems for investigating protein structure and function. The introduction of disulfide bonds and a change in conformation between the cis and trans conformations of the proline peptide bond may be a barrier to the rapid formation of the proper protein structure. In the cell, enzymes are present to catalyse these processes.

Key Concepts:

  • The conformational flexibility around the alpha carbon of peptides connected by peptide bonds accommodates an enormous number of structures depending on the protein sequence.

  • Disulfides are chemical crosslinks between or within polypeptides that adds stability to the overall structure.

  • Conformational transitions involving proline residues in a protein can slow protein folding due to a slow conformational transition.

  • The enzymes protein disulfide isomerase and peptidyl proline isomerase function in the cell to catalyse slow chemical and configuration changes that retard protein folding.

Keywords:

  • peptide structure and function;
  • peptides;
  • disulfides;
  • proline isomerisation;
  • protein disulfide isomerases