Serum protein electrophoresis

This week I am going to write about serum protein electrophoresis.

Serum protein electrophoresis is a laboratory technique for separating proteins in serum whereby the serum is placed onto an inert support medium such as agarose gel (on a plastic support sheet) and then exposed to an electrical field. Proteins in the serum will then migrate and separate based on their net surface charge and molecule size to either end of the electrodes at varying speed. This would then separate the serum protein components into five fractions, in decreasing order of migration speed - albumin, alpha-1 globulins, alpha-2 globulins, beta globulins, and gamma globulins. Once migration process has completed, the protein fractions on the gel can be fixed and stained for visual interpretation.

Scanning of gel can also be done by the densitometer for quantitation in order to provide graphical data on the total and relative amounts of the various proteins.

The factors that may affect the mobility of proteins include size of the protein, charge of the protein (negatively/positively charged), strength of the electrical field and properties of the support medium.
Serum protein electrophoresis (SPE) is used to screen the presence of protein abnormalities (especially M-band) in the serum. SPE also aids in the detection, diagnosis, and monitoring of pathophysiologic conditions associated with these abnormal proteins such as multiple myeloma.

Method:
1. 10ul of samples are pipetted into the wells of the applicator accordingly (1st well is always used for Control).
2. The applicator is then placed in wet storage chamber (teeth facing up) for 3 minutes.
3. Buffered strips are attached to the electrode.
4. The surface of SPE gel is blotted with fine filter paper to remove excess liquid.
5. 200ul of D.I water is applied onto the migration plate (approximately 1/3 from the bottom).
6. The gel is then slowly placed onto the migration plate (ensure that the water is spread across the whole width of the gel & ensure no air bubble is formed).
7. The electrode and the applicator carrier are then lowered down.
8. The applicator is retrieved from the wet storage chamber after 3 minutes.
9. The plastic protective cover of the applicator is then removed carefully.
10. The applicator is placed onto the applicator carrier at the respective position.
11. The lid of the migration module is closed and the required migration program is selected (15/30 PROTEIN [E]).
12. Electrophoresis is conducted.
13. After process is completed, the applicator & buffered strips are removed and discarded.
14. The gel is removed, placed into the gel holder and then slotted into the staining chamber (stained with amido black).
15. Once done, the dry stained gel is removed from the gel holder and scanned.

If there is presence of M-band (distinct band at the gamma region), it will be noted and quantitated. E.g.: Presence of M-band (15g/L).

If the is absence of M-band, it will be noted as well but there is no quantitation.
E.g.: M-band is absence.

If there is presence of a polyclonal protein (broad band at the gamma region), it will also be noted and quantitated.
E.g.: Presence of polyclonal protein (45g/L).

Immunofixation can be done to identify the particular subtype of immunoglobulin heavy and light chains that make up the M-band for classification purposes.

Natasha. 0703883I. :]