Protein  Structural  Metrics  for  Modelling  

•  The  20  standard  amino  acids  share  a  common  structure  but  differ  in  their  side  chains.    •  Pep=de  bonds  link  amino  acid  residues  in  a  polypep=de.      

General Structure of α-Amino Acid

Condensation of Two Amino Acids

Condensation of Two Amino Acids

Pep=de  Bond  

1°, 2°, 3° & 4° Structure

Peptide Bonds Assume Trans Conformation

Resonance of Peptide Bond

Extended Conformation of Polypeptide

Torsion Angles of Polypeptide Backbone

Steric Interference of Adjacent Peptide Groups

The α Helix

β Sheets

Antiparallel β Sheet

Ramachandran Diagram

Parallel β Sheet

Pleating of β Sheet