Very Low Molecular Weight Proteins Electrophoresis Protocol

Background

Electrophoresis is a technique in which using an electric field separates molecules. “A very common electrophoresis method to separate and to denature proteins which uses a discontinuous polyacrylamide gel as a support medium is called Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis (SDS-PAGE). The most commonly used protocol is also called the Laemmli method which refers to the first published protocol of this technique established by Laemmli in 1970 (Ornstein, 1964).

The SDS-PAGE can be used to separate proteins, estimate relative molecular mass, determine the relative abundance of major proteins in a sample, and/or determine the distribution of proteins among fractions. Different staining methods can be used to detect rare proteins and to address their biochemical properties. Rath in her work compares the migration of reference proteins at different gel concentration with gels ranging from 11 to 18% not getting a good resolution in molecules under ~6 KDa (Rath et al., 2013; DeWald et al., 1986).

In order to analyze low molecular weight proteins by this electrophoresis system, high concentration gels are needed, but these gels are very brittle and thus difficult to handle. With a modification of the basic Laemmli SDS-PAGE protocol, proteins with 10 KDa or less will be separated maintaining a good resolution with reproducible results. This method will be explained in this work and demonstrated using 1 KDa and 0.6 KDa proteins as samples.