The document discusses proteins and polypeptides. It defines proteins as polymers of amino acids that perform important structural and functional roles in the body. Proteins are classified based on shape, constitution and nature. Polypeptides are continuous chains of amino acids joined by peptide bonds. They are precursors to proteins and are synthesized through a process involving transcription and translation. Common methods for synthesizing polypeptides include Fischer's method which uses protecting groups to join amino acids, and modifications of this method.

1. DEPARTMENT OF PHARMACUETICAL SCIENCES
PROTIENS AND POLYPEPTIDES
Prepared by: Suhaib Kirmani
Bpharm 3rd yr.

2. PROTIENS : INTRODUCTION
 The Molecules which yields amino acids upon hydrolysis are called proteins.
 Proteins are natural polymer of amino acids.
 The number of amino acids in a protein molecule may range from two to several thousands.
 Protein molecules contain Nitrogen, Carbon, Hydrogen and Oxygen.
 Proteins are the basis for the major structural components of animal and human tissue.
 They act as biological catalysts (Enzymes), form structural parts of organisms, participate in different cell
reactions, act as molecules of immunity and also provide fuel.
Prepared by:
Suhaib Kirmani

3. PROTIENS : CLASSIFICATION
Prepared by:
Suhaib Kirmani

4. CLASSIFICATION
Classification of proteins is done on the basis of the following:
 Shape
 Constitution
 Nature of molecules
 On the basis of shape
 Fibrous protein(Scleroprotein): We can find these proteins in animals and are insoluble in water. Fibrous
proteins are resistant to proteolytic enzymes and are coiled and exist in threadlike structures to form fibres. e.g.
collagen, actin, and myosin, keratin in hair, claws, feathers, etc.
Prepared by:
Suhaib Kirmani

5. CLASSIFICATION
Globular proteins
These proteins, unlike fibrous proteins are soluble in water. They are made up of polypeptides that are coiled
about themselves to form oval or spherical molecules e.g. albumin, insulin, and hormones like oxytocin, etc
On the basis of Constitution
Simple proteins: These proteins are made up of amino acids only. e.g. albumins, globulins, prolamins, etc.
Conjugated proteins: These are complex proteins that are combined with the characteristic of non–amino acid
substance called as a prosthetic group. These are of following types:–
 Nucleoproteins: Combination of protein and nucleic acid
 Mucoproteins: Combination of proteins and carbohydrates (>4%)

6. CLASSIFICATION
 Glycoproteins: Combination of proteins and carbohydrates(<4%)
 Chromoproteins: Combination of proteins and coloured pigments.
 Lipoproteins: Combination of proteins and lipids.
 Metalloprotein: Combination of proteins and metal ions.
 Phosphoprotein: Combination of proteins and phosphate group.
Derived proteins: When proteins are hydrolysed by acids, alkalies or enzymes, the degradation products obtained
from them are called derived proteins.

7. CLASSIFICATION
On the basis of nature of Molecules
 Acidic proteins: They exist as anion and contain acidic amino acids. e.g. blood groups.
 Basic proteins: They exist as cations and are rich in basic amino acids e.g. lysine, arginine etc.

8. STRUCTURE OF PROTIENS
Due to different rearrangement of amino acids, the structure of proteins divides into four types:
 Primary- the covalent linkages of the proteins
 Secondary- the linear peptide chains fold either into an alpha-helical structure(coiled) or a beta-pleated
structure(sheets) which contain hydrogen bonds.
 Tertiary- The arrangement and interconnection of proteins into specific loops and bends forms the tertiary
structures. This structure contains hydrogen, ionic and disulfide bonds.
 Quarternary- this structure is proteins containing more than one peptide chain.

9. FUNCTIONS
Structural functions: Proteins are called as the building blocks of the body. They are an essential component of
various structures in the cell and tissues. We also find these proteins in the outer membrane of all cells in the human
body. We can also find structural proteins in hair, skin, and muscles. Proteins often act to strengthen these
structures. Proteins working together can allow movement within the body, such as contraction of muscles and
movement of food through the digestive system etc. They are needed for the growth, development, healing, and
repair of tissues.
Protective: Proteins are the main constituent of antibodies that protect our body against antigens and pathogens
thus preventing infections.
Hormonal regulation: Hormones are majorly composed of proteins. Hormones play a vital role in regulating
muscle mass, sex hormones, and growth and development.
Enzymes: Proteins are called as biological buffers because they, as enzymes, regulate many different biochemical
reactions that are occurring in the body.

10. EXAMPLES

11. EXAMPLES

12. POLYPEPTIDES
 A polypeptide is a continuous, unbranched chain of amino acids joined by peptide bonds
 Amino acids are the building blocks of larger proteins - they are monomers. Two amino acids join together to
create a dipeptide. Many amino acids join together to create a polypeptide - a protein polymer. A protein is
formed when one or many polypeptide chains fold into a specific shape that allows it to perform a specific
function.
 Two amino acids are joined together by a condensation reaction to form a dipeptide. The condensation
reaction occurs between the carboxyl group (-COOH) and the amino group (-NH2) on adjacent amino acids.
A molecule of water is released as one oxygen and two hydrogen atoms are removed from the amino acids.
This creates a peptide bond which joins the two amino acids together to form a dipeptide. A peptide bond is a
covalent bond formed when two amino acids are joined together in a condensation reaction. Many amino
acids can be joined together in a series of condensation reactions to form a polypeptide. A polypeptide is a
polymer made of many amino acids joined together by peptide bonds.
.

13. POLYPEPTIDES

14. SYNTHESIS OF POLYPEPTIDES
 Polypeptide synthesis is the biological production of peptides, which are organic compounds in which
multiple amino acids are linked via peptide bonds. They are the building blocks of proteins, which are
essential to cell function.
The process involves two steps: transcription and translation.

15. SYNTHESIS OF POLYPEPTIDES

16. SYNTHESIS OF POLYPEPTIDES
General Methods of Polypeptide Synthesis :
 Fisher Method: SECOND
Fisher prepared a polypeptide in 1903 by the condensation of amino acid whose amino group is protected by
means of ethyl chloroformate with an amino ester

17. SYNTHESIS OF POLYPEPTIDES
 The dipeptide derivative formed above may further be converted into tripeptide, by condensing it further with
another ammo acid ester. and thus a polypeptide may be prepared. However. the method suffers from the
serious drawback that the protecting N-cartbethoxyl group cannot be removed by hydrolysis without
affecting the peptide bond with the result the yield of the product is very low.
Fischer's third method :
This method is actually the modification of
the above method and involves the use of p-
toluenesulphonyl chloride as the protective
agent in place of ethyl chloroformate since
the p-toluenesulphonyl also known as tosyl
group can easily removed by means of HI
without affecting a peptide bond. The rest
of the procedure is same and may
represented as in picture aside :

18. THANK YOU