Peptide Bond Part 2: Peptide Bond Structure: Features: Representation of the Peptide Bond (For CBSE, ICSE, IAS, NET, NRA 2022)

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Title: Peptide Bond Part 2

Peptide Bond Structure

Peptide Bond Structure
  • A peptide bond is a planar, Trans, and rigid configuration. It also shows a partial double bond character.
  • Co planarity of the peptide bond denotes the resonance or partial sharing of two pairs of electrons between the amide nitrogen and carboxyl oxygen.
  • Atoms C, H, N, O of the peptide bond lies in the same plane, like the hydrogen atom of the amide group and the oxygen atom of the carboxyl group are trans to each other.
  • Linus Pauling and Robert Corey are the scientists who found that the peptide bonds are rigid and planar.

Peptide Bond Features

Writing of the Peptide Bond Structure

  • Generally, these bonds are written in a form where free amino acids are at the left and the free carboxyl on the right side.
  • Left side is N-terminal residue and the right side is C-terminal residue.
  • This amino acid sequence is read from the N-terminal to the C-terminal. And, the protein biosynthesis also starts in the same direction.

Representation of the Peptide Bond

  • Rattlesnake moving representation is used for the peptide bond representation, from left to right of the page.
  • N-terminal residues to its rattle and C-terminal residues are considered as the fangs.

Shorthand to Read the Peptide Bond

Peptide or protein of the amino acid is represented by the 3 letters or one-letter abbreviation.

The Naming of the Peptide Bond

To name the peptides, we should know the suffixes of the amino acids. -ine for glycine, -and for tryptophan, -ate for glutamate, are changed to -yl except in the case of C-terminal of the amino acid.

Stereochemistry of the Peptide Bond

  • We know that every protein is made of simpler units of amino acids with the L-configuration.
  • The steric arrangement of the alpha carbon is fixed by that configuration.