Protein Structure I​: Properties of Peptide bond, Ramachandran plot, Primary and secondary (alfa-helix, beta-pleated sheet, turns and loops) structures

Proteins and peptides

• ​Proteins and peptides are polymer of L-amino acids joined together with peptide bonds​
• Peptide bond is an amide linkage between the α-amino group of one amino acid and the α-carboxyl group of another, with the elimination of the elements of water.​
• Peptide bond formation is an example of a condensation reaction
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• In a peptide, the amino acid residue at the end with a free -amino group is the amino-terminal (or N-terminal) residue.
• The residue at the other end, which has a free carboxyl group, is the carboxyl-terminal (C-terminal) residue.

• Proteins possessed four levels of structural organization​

  • Primary Structure​
  • Secondary structures​
  1. α-helix ​
  2. β-pleated sheets;​
  3. turns and loops ​
  • Tertiary Structure​
  • Quaternary Structure ​

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