Protein electrophoresis

Protein electrophoresis is a method for analysing the proteins in a fluid or an extract. The electrophoresis may be performed with a small volume of sample in a number of alternative ways with or without a supporting medium: SDS polyacrylamide gel electrophoresis (in short gel electrophoresis, PAGE, or SDS-electrophoresis, free flow electrophoresis, electrofocusing, isotachophoresis, affinity electrophoresis, immunoelectrophoresis, counterelectrophoresis, and capillary electrophoresis). Each method has many variations with individual advantages and limitations. gel electrophoresis is often performed in combination with electroblotting immunoblotting to give additional information about a specific protein. Because of practical limitations, protein electrophoresis is not suited as a preparative method.



Protein electrophoresis in medicine
In medicine, protein electrophoresis is a method of analysing the proteins mainly in blood serum (blood plasma is not suitable). Before the widespread use of gel electrophoresis, protein electrophoresis was performed as free flow electrophoresis, on paper, or as immunoelectrophoresis.

There are two classes of blood proteins: serum albumin and globulin. They are generally equal in proportion, but albumin is much smaller and lightly negatively charged, leading to an accumulation of albumin on the electrophoretic gel. A small band before albumin represents transthyretin (also named prealbumin). Some forms of medication or body chemicals can cause their own band, usually small. Abnormal bands (spikes) are seen in monoclonal gammopathy of undetermined significance and multiple myeloma, and are useful in the diagnosis of these conditions.

The globulins are classified by their banding pattern (with their main representatives):


 * The alpha (α) band consists of two parts, 1 and 2:
 * α1 - α1-antitrypsin, α1-acid glycoprotein.
 * α2 - haptoglobin, α2-macroglobulin, α2-antiplasmin, ceruloplasmin.
 * The beta (β) band - transferrin, LDL, complement
 * The gamma (γ) band - immunoglobulin (IgA, IgD, IgE, IgG and IgM). Paraproteins (in multiple myeloma) usually appear in this band.