Its a presentation on different structures and functions of proteins.

1. Architecture of
proteins
Presented by – Arnabesh Das
Email: dasarnabesh@gmail.com

2.  What are proteins?
 What are proteins made of ?
 Classification of amino acids: selected properties.
 Peptide bonds.
 Protein Structures.
 Classification of Structures.
 Primary Structure.
 Secondary Structure.
 Tertiary Structure.
 Quaternary Structure.
Index

3.  Proteins are large biological molecules,
or macromolecules, consisting of one or
more long chains of amino acid residues.
 Proteins perform a vast array of functions
within living organisms ∼
Catalysing metabolic reactions
Replicating DNA
Responding to stimuli
Transporting molecules from one
location to another.
What are proteins?

4.  Proteins are made up of smaller building
blocks called amino acids, joined together
in chains.
 Some proteins are just a few amino acids
long, while others are made up of several
thousands.
 These chains of amino acids fold up in
complex ways, giving each protein a
unique 3D shape.
 There are 20 different amino acids.
What are proteins made of ?

5. Classification of Amino acids: Selected
properties

6.  The amide group is planar with N-H
trans to C=O (trans-peptide bond).
 C-N of the peptide bond has partial
double bond -character.
Peptide bonds

7.  Protein structure is the bio molecular structure
of a protein molecule.
 Proteins are polymers – specifically
polypeptides -sequences formed from various L-
α-amino acids. Each unit of a protein is called an
amino acid residue because it is the residue of
every amino acid that forms the protein by
losing a water molecule.
 proteins fold into one or more specific spatial
conformations, driven by a number of non-
covalent interactions such as hydrogen bonding,
ionic interactions, Van der Waals forces, and
hydrophobic packing.
Protein structures

8.  Depending on the complexity of
the structure, it can be classified
as –
1) Primary structure
2) secondary structure
3) tertiary structure
4) quaternary structure
Classification of Structures

9.  The primary structure of a peptide or protein
is the linear sequence of its amino acid
structural units, and partly comprises its
overall bimolecular structure. By convention,
the primary structure of a protein is reported
starting from the amino-terminal (N) end to
the carboxyl-terminal (C) end.
 The amino acids differ in structure by the
substituent on their side chains. These side
chains confer different chemical, physical and
structural properties to the final peptide or
protein.
 Each amino acid has both a one-letter and
three-letter abbreviation. These abbreviations
are commonly used to simplify the written
sequence of a peptide or protein.
Primary Structure

10.  The term secondary structure refers to
the interaction of the hydrogen bond
donor and acceptor residues of the
repeating peptide unit.
 The two most important secondary
structures of proteins, the alpha helix
and the beta sheet, were predicted by
the American chemist Linus Pauling in
the early 1950s.
 Both the alpha helix and the beta sheet
represent a way of saturating all the
hydrogen bond donors and acceptors in
the peptide backbone.
Secondary structures

11.  The tertiary structure of a protein is a
description of the way the whole chain
(including the secondary structures) folds
itself into its final 3-dimensional shape.
 Shape is stabilized by various interactions,
among the R groups of polypeptide chain.
Tertiary structure

12.  The quaternary protein
structure involves the clustering
of several individual peptide or
protein chains into a final
specific shape.
 There are two major categories
of proteins with quaternary
structure - fibrous and globular.
Quaternary Structures

13. Thank
You
Email : dasarnabesh@gmail.com