Oliver Smithies [b. 1925), a scientist working at the University of Toronto in the 1950s, discovered a way for scientists to separate proteins quickly and easily by their size, using potato starch to create a type of microscopic sieve.
Smithies, who was one of three scientists sharing the 2007 Nobel Prize in Physiology or Medicine, was looking for a way to separate insulin from its precursor when he developed starch-gel electrophoresis. Using potato starch, Smithies created a gel that allowed proteins to be separated by size. He found that the best potato starch came from a powder produced in Canada. Later, when Smithies worked at the University of Wisconsin, he made many trips from Madison, Wisconsin, to Toronto to obtain this special powder.
The powder was used as a matrix in the gel. The proteins were applied to the gel and exposed to an electric charge, which allowed them to migrate through the matrix of potato starch. The starch acted as a Sieve and enabled scientists to see the size separation of the proteins that they were studying.
Although electrophoretic methods had been developing since the late 1930s, this method of size separation by a sieve created from powder was an important advance in protein science. Smithies' initial device for starch-gel electrophoresis proved to be quite bulky. The equipment used to run the electric current did not produce a constant current, and the gels used, which were about 0.4 inches (1 cm) thick, were excessive by today's standards.
Improvements to the process were developed over the next few decades. Today, gel electrophoresis equipment is much more streamlined, but the simple sieve idea that Smithies discovered still forms the basis of protein separation.
