So, I’ve been very busy in Labs this last week, Mainly running Western Blots and running Coomassie gels, which I am still uncertain on how to pronounce ( Co- like co-op, or Coo like a bird ?). Well anyways I have been doing them to look at antibody purification protocols and whilst they may seem fairly primitive techniques they remain some of the most powerful and cost effective in biochemistry.
Working according to the principle that a charged object travels towards an opposing charge, in a speed directly proportional to its charge and size, as proteins are separated by travelling across a gel matrix. In SDS-Page, the technique i have been using SDS is added to the protein which is heated in order to break disulphide bonds and denature the protein. this removes the effect of shape and keeps the Molecular Weight (KDa):volume ratio constant so, proteins are separated uniformly by their molecular weight.
Electrophoresis began after the early work of Faraday, when scientists such as Kohlrauch, Nernst and Hittorf would put charged particles one side of a U shaped tube then by applying a charge would observe it migrate across to the opposing electrode.During this period a whole variety of compounds were tested, which eventualy lead to testing the mobility of proteins affected by an electrical charge.
More sensitive methods were eventually devised by a swede Arne Tiselius, which eventually lead to him winning him the 1948 Nobel Prize in Chemistry. He worked in Upsalla in the 1930’s initially with solution only systems, however due to the faster motion of particles in liquid systems proteins traveled too fast and little separation was observed. By the 40’s he had moved towards filter papers and gels, taking the ideas from classical organic chromatography in order to slow down migration and improve the resolution of different molecular weight proteins.
Across this period the gels used varied significantly, some of the earliest gels used were sucrose gels, which then were replaced by starch and eventually Acrlamyde gels. This key development by Raymond & Weitraub allowed for the determination of pore size within the gel, allowing a more regular pathway through the matrix and more even results. The next breakthrough towards SDS-Page was the introduction of SDS as a denaturing agent, introduced by Weber and Osborn this lead to the high resolution protein separation methods that we use on a routine basis.
For a routine technique used in Genetics and molecular biology as well as a range of other Biological sciences I find it settling to think that it only works due to physics, the studies of charge, current and motion of charged particles under Bias are all Physics problems, something which many biologists probably often forget whilst waiting for a gel to run. I think this is a really good demonstration of what works when you break down the boundaries and look at a problem and how it can be solved form another perspective. Some great early 20th Century cross-disciplinary work.