Download Peptide Bond - Prof. Raheel Qamar

Peptide Bond
Raheel Qamar, PhD.
Professor of Biosciences
COMSATS Institute of Information
Technology
Islamabad
Protein Structure
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Peptide Bonds
Primary Structure
Secondary Structure
Tertiary Structure
Quaternary Structure
a. Globular Proteins
b. Fibrous Proteins
• Protein Folding
• Protein Denaturation
Proteins are Built from a Repertoire of
20 Amino Acids
ENERGY
PEPTIDE
BOND
H3N+
N or
Amino Terminus
Back Bone
(Main Chain)
Residues
(glycyl, glutamyl etc)
COOC or
Carboxyl T
Components of a Polypeptide Chain
Peptide bond
Amino
terminal
residue
Carboxyl
terminal
residue
Peptide Bonds
Polar & Planar
α2
α1
1.49 0A
Partial Double-Bond Character
α2
α1
Trans Configuration
1.27 0A
α2
α1
1.32 0A
A Polypeptide Chain
Peptide Bond
R2
Ο
C
N
Η
Cα
R1
Η
(Glycine)
N
Cα
C
Ο
R4
C
N
Valine & Glycine in Trans Configuration
Cα
N
Cα
Η
(Valine)
(Serine)
Η
Ο
R3
(Aspartic acid)
C
N
Ο
Η
PeptidePGroup
1.24
1.32
1.51
Phi Φ
Rigid Unit
1.46
Ψ Psi
Rigid Unit
The Standard Dimensions in Trans & Cis Peptide
Group
Trans Peptide Group
Cis Peptide Group
Steric Hindrance between adjacent peptide units
Pro Trans & Cis Configuration
Trans
Cis
Characteristics of the Peptide Bond
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Partial Double-Bond
Rigid & Planar
Trans Configuration
Uncharged but Polar
Φ ψ Angles and Rotation about Bonds
on a Polypeptide
Ramachandran diagram