protein

2. Group Leader: Mohammad Raes.
Group Members:
•Aster Naz.
•Safia.
•Zareena Khatoon.

3. Subject: Biochemistry.
Faculty: Sir Ajmal Khan.
Topic: Chemistry of Proteins.
Date: 07th March, 2016.

4.  Definition of Protein.
 General Chemistry of Amino acid.
 Composition.
 Amphoteric Nature.
 Structure of Protein.
 Classification of Protein.
 Properties of Proteins.
 Denaturation of Protein.
 Function of Protein.
 Biological Importance of Protein.
Objectives:

5.  Any of a group of complex organic macromolecules
that contain Carbon, Hydrogen, Oxygen, Nitrogen
and usually sulphur and are composed of amino
acids is called Protein.
 Protein include many substances such as enzymes,
hormones, antibodies etc. that are necessary for the
proper functioning of an organism.
 They are essential for growth and repair of tissues in
an organism.
Protein:

6.  Amino Acids are the building units of proteins.
Proteins are polymers of amino acids linked
together by what is called “ Peptide bond”.
 There are about 300 amino acids occur in nature.
Only 20 of them occur in proteins.

7.  Each amino acid has 4 different groups attached
to α- carbon ( which is C-atom next to COOH).
These 4 groups are :
 amino group,
 COOH group,
 hydrogen atom.
 side chain (R).

9.  Essential Amino acid
 Non-essential Amino acid.
 Semi-essential Amino acid.
 Acidic Amino acid.
 Basic Amino acid.
 Aromatic Amino acid.
 Sulphur Amino acid.
 Side Chain-OH Amino acid.

10.  Essential Amino Acid:
Those amino acid which are not synthesized
in living organism and they have to ingest
them.
e.g.
Isoleucine, Leucine, Methionine, Lysine.
 Non-essential Amino Acid:
The amino acid which are continuously
synthesized in our body are called non-
essential amino acid.
e.g.
Alanine, Asparagines, Aspartic Acid, Cysteine.

11.  Semi-essential amino acid:
Amino acid which are present in our body
but not in adequate amount are called semi-
essential amino acid.
 Acidic Amino Acid:
They have more carboxyl group rather than
amino group i.e. 2 carboxyl group and 1
amino group.
e.g.
Aspartic acid, Asparagine, Glutamic acid,
Glutamine.

12.  Basic amino acid:
They have more amino group rather than
carboxyl group i.e. 2 amine group and 1
carboxyl group.
e.g.
Arginine, Lysine, Hydroxylysine, Histidine.
 Aromatic Amino acid:
They contain aromatic (benzene) ring in their
molecules.
e.g.
Phenylalanine, Tyrosine, Tryptophan

13.  Sulphur Amino acid:
Contain sulphur in their structure.
E.g. Cystine, Cysteine, Metheone.
 Side Chain-OH Amino acid:
They contain OH in their group.

14.  An α-amino acid in which the functional
group attached to the α-carbon (R in
RCH(NH3+)COO−) has hydrophilic
properties, serine, cysteine,
homocysteine.

15.  Non Polar Amino Acids have equal number
of amino and carboxyl groups and are
neutral. These amino acids are hydrophobic
and have no charge on the 'R' group. The
amino acids in this group are alanine,
valine, leucine, isoleucine, phenyl
alanine, glycine, tryptophan, methionine
and proline.

16.  Zwitter Ion:
Neutral amino acids (monobasic,
monocarboxylic) exist in aqueous solution
as “ Zwitter ion” i.e. contain both positive
and negative charge. Zwitter ion is
electrically neutral and can’t migrate into
electric field.

17.  Amino acids are Amphoteric organic
acids that contain the amine group, -NH2
and the carboxylic acid group -COOH.
Amine groups are basic ( you could say
they are a modified form of the ammonia
molecule) and carboxylic are acidic.
 As an example of the Amphoteric nature
of an amino acid, we can look at Glycine,
which is chemically, the simplest of the
amino acids.

18.  Two amino acids joined by one
peptide bond.
 Example: Aspartame which acts as
sweetening agent being used in
replacement of cane sugar. It is
composed of aspartic acid and phenyl
alkaline.

20. There are four levels of protein structure:
 Primary.
 Secondary.
 Tertiary.
 Quaternary.

21. The primary structure of a protein refers
to the linear sequence of amino acids in the
polypeptide chain. The primary
structure is held together by covalent
bonds such as peptide bonds, which are
made during the process of
protein biosynthesis.

23.  The folding of the polypeptides chains into
a specific coiled structure held together by
disulfide and hydrogen bonds is called
secondary structure of protein.
 It consist of:
 a- helix
 b- pleated sheet
 b- bends
 Non repetitive structure.
 Super secondary structure.

25.  The 3D (Three-dimensional) structure of
an entire amino acid chain is called
tertiary structure. Is determined by a
variety of interactions (bond formation)
among R groups and between R groups
and the polypeptide backbone.

27.  Arrangement of two or more polypeptide
chains into multi subunit molecule.
 Results from the aggregation
(combination) of two or more polypeptide
subunits held together by non-covalent
interaction like H-bonds, ionic or
hydrophobic interactions.

31. Protein can be classified into three
groups.
1. Simple proteins.
2. Conjugated proteins.
3. Derived proteins.

32.  Simple proteins are proteins which on
hydrolysis yields only amino acids and
possess no non-protein part in molecules.
 Major subclasses of simple proteins are as
follows:
 Protamines
 Histones
 Albumin
 Globulin

33.  Glutelins
 Prolamines
 Sceloproteins (albuminoids).
 Keratins
 Collagens
 Elastins.
 Conjugated Proteins:
Conjugated proteins are complexes of
simple protein and with non-proteins; the
protein part is called apoprotein and the
non-protein part is called prostheticc group
and the entire molecules is known as
holoprotein.

34.  Conjugated proteins are classified on the
basis of prosthetic group.
 Subclasses of conjugated proteins are:
I. Nucleoproteins.
II. Mucoproteins.
III. Glycoprotein.
IV. Chromoproteins.
V. Phosphoproteins.
VI. Lipoprotiens.
VII. Metalloproteins.

35.  Derived proteins are produced from
natural proteins by various physical and
chemical factors and divided into two
major groups:
a) Primary protein
b) Secondary protein

36.  They are coagulated and denatured
proteins.
 Proteans Heat, water, X-Rays, UV Rays,
agitation, or alcohol change soluble
globular proteins like ovalbumin to fibrous
insoluble, coagulated and denatured
proteins.
 Metaprotein and coagulated protein are
the subclasses of primary protein

37.  Progressive hydrolysis of peptide bonds
breaks the protein into progressively smaller
molecules called proteases, peptones and
peptides. They are generally soluble in
water and not coagulated by heat.

38.  Collagen:
Holds the tissues together.
 Keratin:
Toughens and waterproofs the skin.
 Hormone:
Regulate body function.
 Actin and Myosin:
Relaxation and contraction.

39.  Hemoglobin:
Transfer Oxygen.
 Antibody:
Fights infection.
 Enzymes:
Assist other chemical to react with each
other.
 Defense protein:
Immunoglobulin are involved in defense
mechanisms.

40.  Contractile protein:
Protein of skeletal muscle are involved in
muscle contraction and relaxation.
 Respiratory protein:
These involved in the respiration. E.g.
Hemoglobin.
 Structure protein:
These are the protein of skin, cartilage
and nail.

41. There are two types of properties
1. Physical Properties.
2. Chemical Properties.

42. 1-Proteins are mainly water soluble which
is explained by its polarity and the
presence of charged groups. They are
soluble thus in polar solvents and not
soluble in non-polar solvents.
2-They have a high melting point reflecting
the high energy needed to break the ionic
forces.

43. 3. Colorless
4. Crystalline
5. May be sweet (glycine, alanine)
6. Tasteless (leucine)
7. Bitter (Arginine)
8. Colloidal Nature: Hydration shell and
electric repulsion make proteins stable
in solution.

44. 9. Viscosity
10. Amphoteric nature.
11. precipitation.

45.  Denaturation of protein:
Denaturation is a process in which protein
or nucleic acid loose the Quaternary
structure, tertiary and secondary structure
which is present in their native state by
application of some external stress or
compound such as strong acid or base a
concentrated inorganic salt, an organic
solvent e.g. alcohol, radiation of heat.

47.  Physical agent:
Heat, UV Lights, Ultrasound, High
Pressure etc.
 Chemical agent:
Organic solvent, acid and alkalis, urea
and various detergent.
Denaturation destroys enzyme and
hormonal activity but increase digestibility
of protein.

48.  Membrane Formation:
Protein and lipid form the major structural
component of cell membrane.
 Enzymes:
Enzyme are Protein in nature and are
biocatalyst which influence the rate of
chemical reaction usually without
undergoing any change in themselves.

49.  Homeostasis:
Several hormones are peptides and
proteins. They play an important role in
the regulation of homeostasis.
 Blood proteins:
The blood proteins include plasma
proteins and hemoglobin.
a. Plasma proteins:
Albumin
Globulin
Fibrinogen

50.  Albumin:
Maintain the colloid osmotic pressure of
plasma and transport material.
 Globulin:
Inhibit proteolytic enzymes and promote
immune system of the body..
 Fibrinogen:
Help in blood clotting.
b. Hemoglobin:
Carry oxygen in the form of oxyhemoglobin
in blood.

51.  Antibodies:
Resist against viable pathogen.
 Nucleoproteins:
These are conjugated protein of cell nuclei.
 Collagen:
Found in connective tissue.
 Contractile Protein:
Actin and myosin help in contraction and
relaxation of muscle.