for Medical, Paramedical & allied Health sciences students

1. Good morning
Have a nice day to all

2. PROTEINS
Large, complex molecules formed by amino acids.
Component of every cell in the body

3. Functions of Proteins
Controls & Regulates gene
transcription & translation
Provides strength and elasticity to
organs & tissues
Form the matrix of bone &
connective tissues
Act as Enzymes, Receptors and
Transporters
Necessary for the proper growth &
functions of the body
Involved formation of Peptide
hormones

4. 1) Peptide bond is
a) single bond in character b)double bond in character
c) partial double bond in character d) triple bond in character
2) Alpha helix and beta sheets are the structural patterns of
- Secondary structure
3) Alpha helices found in proteins are mostly
a) Right handed b) left handed c) both are equal d) none
4) Peptide bond occurs in ____________isomeric form
- Trans form
MCQs

5. 5) The organization of beta pleated sheet is
a) stabilized by extensive hydrogen bonding ,
b) the peptide backbone of the sheet is partially extended
c) composed of both the parallel and anti-parallel sheets
d) all the above
6) Secondary , and tertiary structures of large polypeptides are organized into
structurally connected, but functionally independent units known as
a) loops, b) reverse turns, c) domains, d) none of the above
MCQs

6. CLASSIFICATION
OF
PROTEINS

7. Functional
Chemical nature & Solubility properties
Nutritional imp
Proteins are classified in several ways, major types of classification based on,

8. Simple Proteins
Conjugated Proteins
Derived Proteins
1. Based on the chemical nature & Solubility
Joint committee of the American society of biological chemists & American physiological society

9. Globular proteins or spheroproteins
a) Simple Proteins
Insoluble, high molecular weight fibers
Eg: Collagens, fibrin, Keratins
Soluble, low molecular weight , ovoid shape
Eg: Albumins, Globulins, Histones
Composed of only
amino acid residues

10. Glycoproteins
eg: Mucin (saliva), Igs, TSH, FSH & LH Lipoproteins
eg: Serum lipoproteins
B) Conjugated Protein
Nucleoproteins
Nucleic acid (DNA& RNA)
eg: Histones, protamines.
Phosphoproteins
eg: Casein of milk, Egg yolk
Metalloprotein
(Metallic elements) eg: Ceruloplasmin
(Cu), Peroxidase & Catalase (iron) &
Carbonic anhydrase (Zn)
Made up of a.as & non-protein part which maybe organic & inorganic
Chromo-protein
(color Pigment )
Hemoglobin, myoglobin, rhodopsin

11. Protein
Proteans
Metaproteins
Proteoses
Peptones
Peptides
Amino acids
a) Primary derivatives (denatured
proteins)
b) Secondary derivatives
C) Derived Proteins
Don't occurs as such in nature
Formed from naturally occurring proteins by the action of
physical agents or chemical agents

12. Structural Proteins Keratin of hair, Collagen of bone.
Catalytic Proteins All enzymes
Transport proteins Hemoglobin, Serum albumin,
Receptor Proteins Hormone receptors, LDL receptor, T- cell receptor etc
Contractile Proteins Actin and myosin
Defense proteins Immunoglobulin
Lubricant proteins Mucin - also protects the mucosa
02. Based on Functions

13. Complete Proteins
(Egg Albumin, Milk Casein)
Incomplete Proteins
[Proteins from pulses –Metheonine
Protein of cereals – lysine
Gelatin -Tryptophan
03. Based on
Nutritional imp

14. Denaturation
of
Protein

15. The disruption of native protein structure.
Mainly rupture of ionic bond, H-bonds & hydrophobic bond but
peptide bonds are not hydrolysed.

16. Denaturing agents
Physical agents
Heat, UV rays & Ionizing radiations
Chemical agents
Strong alkalies & acids, salts of heavy metals
Organic solvents
Alcohol & Urea solution

17. Denaturation of protein leads to.
• It loses its biological activities
• It is usually irreversible
• Decrease in solubility & increase in precipitability.
• Denatured proteins will have more exposed areas for enzymatic action (cooked foods are
more easily are easily digested and cannot be crystallized).

18. Structure & Functional Relationship
of proteins
Three dimensional structural conformation provides & maintains the functional
characteristics that dependent on the primary structure.
Any difference in the primary structure may produce a protein, which cannot serve
its function.

19. Enzymes
• All are proteins catalyst of chemical reaction in biological systems
• Increase the rate of chemical reactions taking place within living cells
without participating in the reaction.

20.  In enzymatic catalysis is depends
on the structural conformation of
the active site of the enzyme, is
precisely oriented for substrate
binding.
 Active site possesses three
dimensional structure
 Binding residues: Recognize &
bind the correct substrate to form
ES complex
Specific amino
acid residues

21. • Catalytic residues: Create a chemical
environment that enhances the reaction
rate and converts ES complex to E and P
• Change in the 1O, 2O, 3O & 4O structure may
alter the 3 dimensional shape of the active site
of the enzyme & reduces its binding and
catalytic activity

23. Hemoglobin
• Conjugated proteins (Heme +globulin)
• It is a tetrameric protein (HbA1:2-α-chains
& 2β / HbA2 :2α & 2δ & / HbF: 2 α & 2 γ
subunits) with each monomer having a
heme unit.
• Chains of the globin of Hb are synthesized
from a.a’s under genetic control.

24. • Mutations in the genes that code for globin chain
can affect their formation & function of Hb.
• When biological function is altered due to
mutation in hemoglobin- hemoglobinopathy
• Thalassemia: due lack or decreased synthesis of
either α or β -globin chain
• Sickle cell disease by altered sequence of amino
acids in one of the β-globin chains)

25. HbA: “N”end -Val-His-Leu-Thr-Pro-Glu-Glu-Lys- C end ------- (β- chain)
HbS: “N”end -Val-His-Leu-Thr-Pro-Val-Glu-Lys - C end
6th
Non polar , nonionic hydrophobic amino acid
Polar ,acidic, hydrophilic amino acid
Sickle cell anemia
6th