introduction and types and its properties

1. FACILITATED TO –
SRINIVAS RAO SIR
ASSISTANT PROFESSOR
(PH. ANALYSIS)
SUBMITTED BY-
SANTHOSH KUMAR T S
M.PHARM
1ST YEAR
PRESENTATION ON :
ELECTROPHORESIS
KARNATAKA COLLEGE OF PHARMACY
BANGALORE

2. CONTENTS
1) Introduction about electrophoresis
2) Principle
3) Theory
4) Electrophoretic Techniques
5) Applications
6) Types of electrophoresis

3. Introduced by ARNE TISELIUS in 1937, for the separation of
proteins.
Defined mainly as the migration of charged molecules under the
influence of an external magnetic field.
This method is used for the separation of
A) Proteins
B) Nucleic acid
C) Polysaccharides
INTRODUCTION

4. Electrophoresis is a physical method of analysis which
involves separation of the compounds that are capable of
acquiring electric charge in conducting electrodes.
Electrophoresis may be defined as the migration of the
charged particle through a solution under the influence of an
external electrical field.
 Ions that are suspended between two electrodes tends to
travel towards the electrodes that bears opposite charges.

6. PURPOSE FOR CARRYING OUT
ELECTROPHORESIS
1. To determine the number, amount and mobility of
components in a given sample or to separate them.
2. To obtain information about the electrical double layers
surrounding the particles.
3. Determination of molecular weight of proteins and DNA
sequencing

7. PRINCIPLE
• Any charged ion or molecule migrates when placed in an
electric field.
• The rate of migration depend upon its net charge, size, shape
and the applied electric current.Rate of migration (separation)
depends upon e/m (charge to mass) ratio
• The migration of particles or the rate of travel of particle, in
electrophoretic system depends on properties of the
particles as well as the instrumental system
1. Characteristic of particles
2. Property of electric field
3. Temperature
4. Nature of suspended medium

8. ELECTROPHORETIC MOBILITY
It is defined as the rate of migration (cm/sec) per unit field
strength (volts/cm) .
Mobility of particle is calculated by Strokes law:-
μ = Q/6πr η
where Q = charge on the particles
μ = mobility of particle
r = radius
η = viscosity of the medium

9. FACTORS AFFECTING ELECTROPHORETIC
MOBILITY
1 Charge – higher the charge greater the electrophoretic
mobility.
2 Size – bigger the molecule greater are the frictional and
electrostatic forces exerted on it by the medium. Consequently,
larger particles have smaller electrophoretic mobility compared
to smaller particles.
3. Shape – rounded contours elicit lesser frictional and
electrostatic retardation compared to sharp contours. Therefore
globular protein move faster than fibrous protein.

10. THEORY
 Migration of charged particles on potential gradient and space
in between 2 electrodes.
Hence field strength (x) = E/S
Where,
E = Potential gradient applied
S = space between 2 electrodes
basically electrophoresis is an
 a separation technique
 Simple, rapid and highly sensitive
 used in clinical laboratories to separate charged molecules
from each other in presence of electric field
 Proteins in body fluids: serum, urine, CSF
 Proteins in erythrocytes: hemoglobin
 Nucleic acids: DNA, RNA

11. The rate of migration of an ion in electrical
field depend on factors,
1. Net charge of molecule
2. mobility
3. Size and shape of particle
4. Strength of electrical field
5. Properties of supporting medium
6. Temperature of operation

12. 1. Mobility
Under the electrical field, the mobility of the particle is
determined by two factors:
 Its charge
 Frictional coefficient
2. Size and shape
Size and shape of the particle decide the velocity with which the
particle will migrate under the given electrical field and the
medium

14. 3. Strength of electrical field
 It determined by the force exerted on the particle, and the
charge the particle carrying.
F=QV
 when force is exerted on the particle it start moving,
however the moment is restricted by the experience of the
frictional force because of the viscosity.

15. 4. Supporting medium
 Supporting medium is an matrix in which the protein
separation takes place.
 Various type has been used for the separation either on slab
or capillary form.
 Separation is based on to the charge to mass ratio of protein
depending on the pore size of the medium, possibly the
molecular size.
Starch gel
 Cellulose acetate
 Agarose
 Polyacrylamide gel.

16. 1. Agarose Gel
 A linear polysaccharide (made-up of repeat unit of
agarobiose-alternating unit of galactose and 3,6-
anhydrogalactose).
 Used in conc as 1% and 3%.
Pore size is controlled by the % of agarose used.
 It can be stored for longer duration.
2. Cellulose acetate
Thermoplastic resin made by treating cellulose with acetic
anhydride to acetylate the hydroxyl group.
 As the film is soak in buffer, the space are filled.
 Because of their opacity, the film has to be made transparent
by soaking in 95:5 methanol:glacial acetic acid.

17. 3. Polyacrylamide
Frequently referred to as PAGE.
 They are defined in terms of total percentage of acrylamide
present, and pore size vary with conc.
 Made in conc between 3-30% acrylamide.
 Proteins are separated on the basis of charge to mass ratio
and molecular size, a phenomenon called Molecular sieving.

18. 4. Effect of pH on Mobility
 As the molecule exist as amphoteric , they will carry the
charges based on the solvent pH.
 Their overall net charge is NEUTRAL when it is at zwitter ion
state. And hence the mobility is retarded to zero.
 Mobility is directly proportional to the magnitude of the
charge, which is functional of the pH of solvent.
 The pH is maintained by the use of Buffers of different pH.

19. ELECTROPHORETIC TECHNIQUES

20. Electrophoresis Separation
When performed on precast or agarose gel, following
steps are followed;
 Excess buffer removed
 5-7 μL sample
 Placed in electrode chamber
 Current application
 Gel is rinsed, fixed and dried
 Stained
 Scanned under densitometry

21. STAINING
Protein is precipitated in gel by using acetic acid or
methanol
( this will prevent the diffusion of protein out of the gel
when submerged in staining sloution)

22. Different stains of Electrophoresis
 Plasma Proteins
1 Amido black
2 Coomassie Brilliant Blue
3 Bromophenol Blue
Hemoglobins
1 Amido black
2 Coomassie Brilliant Blue
3 Ponceau Red
Lipoproteins
Sudan Black
 DNA ( Fluorescent dyes)
1 Ethidium Bromide
2 Sybr Green, Sybr Gold

24. ADVANTAGES
 Easy to prepare and small concentration of agar is required.
 Resolution is superior to that of filter paper.
 Large quantities of proteins can be separated and recovered.
 Adsorption of negatively charged protein molecule is
negligible.
 It adsorbs proteins relatively less when compared to other
medium.
 Sharp zones are obtained due to less adsorption.
 Recovery of protein is good, good method for preparative
purpose
Gels are stable over wide range of pH and temperature.
 Gels of different pore size can be formed.
Simple and separation speed is good comparatively.

25. DISADVANTAGES
 Electro osmosis is high.
 Resolution is less compared to polyacrylamide gels.
 Different sources and batches of agar tend to give different
results and purification is often necessary.
APPLICATION
 Widely used in Immuno electrophoresis.

26. Clinical applications of Electrophoresis
 Serum Protein Electrophoresis
 Lipoprotein Analysis
 Diagnosis of Haemoglobinopathies and Haemoglobin A1c
 Determination of Serum Protein Phenotypes and Micro
heterogeneities eg. α1- antitrypsin deficiency, MM
 Genotyping of Proteins eg. ApoE analysis for Alzheimer’s
disease (polymorphic protein)

27. TYPES OF ELECTROPHORESIS
1) Zone Electrophoresis
 Paper Electrophoresis
 Gel Electrophoresis
 Thin Layer Electrophoresis
 Cellulose acetate Electrophoresis
2) Moving Boundary Electrophoresis
 Capillary Electrophoresis
 Isotachophoresis
 Isoelectric Focussing
 Immuno Electrophoresis

28. THANK YOU

29. DO YOU HAVE ANY QUESTIONS

31.  The buffer in electrophoresis has two fold purpose:
1 Carry applied electrical current
2 They set the pH as which electrophoresis is carried out.
 Thus they determine;
1 Type of charge on solute.
2 Extent of ionization of solute
3 Electrode towards which the solute will migrate.
4 The buffer ionic strength will determine the thickness of the ionic cloud
Commonly buffers used;
Buffer pH value
Phosphate buffer around 7.0
Tris-Borate-EDTA buffer (TBE) around 8.0
Tris-Acetate EDTA buffer (TAE) above 8.0
Tris Glycine buffer (TG) more than 8.5
Tris -Citrate-EDTA buffer (TCE) around 7.0

32. 32
Solution condition
 The solution conditions are important variables.
 For eg. An acidic pH would favors protonation of basic
centers of a protein, producing a –ve charged molecule.
 It is not desirable to choose a pH such that the protein is at its
isoelectric point and exists as the uncharged Zwitterions( a
species not mobile in the imposed electrical field)

33. 33
Ionic strength
 Electrophoretic mobility decreases with the supporting
electrolyte ionic strength
 Generally, the ionic strengths employed in electrophoresis
range from 0.01 to 0.10.
 The temperature of the solution is important because the
solution viscosity varies with temperature and the
mobility inc. with temperature
Temperature