ELECTROPHORESIS Flashcards
Seen in diagnostic laboratories
ELECTROPHORESIS
migration of charged solutes or particles in a solid medium under the influence of an electrical field/current.
ELECTROPHORESIS
Two types of electrophoresis:
Zone electrophoresis
Iontophoresis
– separation of macromolecules on an electromagnetic field or support medium under the influence of electric current
Zone electrophoresis
– separation of small particles such as ions or electrolytes (Ex. Separation of Calcium ions in a substance)
Iontophoresis
– most important macromolecule
Protein
Zwitterion
AMPHOLYTE
amphoteric pH (can act as either acid+cathode or base-anode) depending upon the support medium where they are found
AMPHOLYTE (Zwitterion)
takes a positive charge (binds protons) at an acidic pH and migrates toward the cathode
Cathode
negative electrode
Cathode
it tends to bind with proton = receives a proton = carries a positive charge
Cathode
takes a negative charge (loses protons) at an alkaline pH and migrates toward the anode - more common
Anode
positive electrode
Anode
it tends to donate and give up proton = loses a proton = carries a negative charge
Anode
generated from electrophoresis
ELECTROPHORETOGRAM
display of protein zones, each one (fraction) sharply separated from neighboring zones on the support medium/material
ELECTROPHORETOGRAM
Per column represents one [?] (serum or any biological sample).
sample
Different fractions per column represents one [?].
protein fraction
The thicker the protein zone, the higher the [?].
protien concentration
FACTORS AFFECTING MIGRATION:
Net electrical charge of molecule (pH of buffer)
MW of the particle
Strength of the electrical field
Type of support medium
The heavier the protein, the slower it migrates
MW of the particle
Ex. Serum protein electrophoresis – smallest protein founf in normal serum: [?], which migrates the fastest
Albumin
Constantly maintained
Strength of the electrical field
A strip of paper can be moistened using a specific buffer to be used for electrophoresis.
The specific sample subjected to electrophoresis will be applied.
The filter paper can be placed between two glass slides.
Both ends of the filter paper (electrodes) must be in contact with the electrolyte solution found in the two chambers (containers)
Electric current will be applied to facilitate the separation of proteins placed on the paper.
PAPER ELECTROPHORESIS
PAPER ELECTROPHORESIS DRAWBACKS
excessive background failing
electrophoresis time may be longer when paper is utilized
too many shadows found per fraction instead of very distinct, clearly demarcated zones
excessive background failing
Type of support medium
- Paper
- Starch (starch gel)
- Cellulose acetate
- Agarose gel
- Polyacrylamide Gel
medium is prepared before electrophoresis
Starch (starch gel)
greater resolution
Cellulose acetate
faster & permanent
Cellulose acetate
distinct zones are separated
Cellulose acetate
most commonly used in electrophoresis
Cellulose acetate
most commonly used in electrophoresis
Agarose gel
High Resolution Electrophoresis
Polyacrylamide Gel
most commonly used medium in isoelectric focusing
Polyacrylamide Gel
- 45 minutes to 1 hour
AGAROSE GEL ELECTROPHORESIS
- Mix the agarose with the buffer of choice
- Heated in a microwave until such time that the buffer agarose is completely dissolved
- The agarose mixture will be poured into the mould
4 . At one end of the mould, a comb is inserted
AGAROSE GEL ELECTROPHORESIS
TYPES OF BUFFER
- Barbital (pH 8.6)
- Citric Acid – PO4 (pH 6.0-6.2)
- Tris-Boric EDTA (pH 8.4-8.6)