I love staining protein gels or membranes. There’s something so fascinating about seeing proteins with your own eyes. Protein electrophoresis We separate proteins by size by loading protein mixtures onto a vertical gel. When electrical current is applied across the gel, proteins (which are negatively charged) will migrate along with the current, travelling through the gel. The gel contains tiny pores which allow proteins to move through it. Small proteins can move easily through these pores but large proteins will lag and move slower due to their size. Therefore, smaller proteins will travel further and end up towards the bottom of the gel, whereas larger proteins will travel a shorter distance and end up towards the top of the gel. The result is this band pattern, where proteins are arranged in decreasing size from the top of the gel to the bottom.
On the outer edges of the membrane (in blue), we’ve loaded a protein ladder. This is a commercial mixture of proteins which has been stained blue and contains multiple proteins of a range of known sizes. These are run and separated on a protein gel along with our protein mixtures so that we can compare the bands in our protein mixtures (stained in red) with the bands in the protein ladder (blue) and therefore calculate the size of our proteins.
