Oct. 31, 2018

The pungent bite of horseradish is familiar to most. Horseradish, along with its cousin wasabi, are used for their effects in condiments and dishes the world over - but horseradish has an important role that most people have never heard of. Enter horseradish peroxidase (HRP). HRP is a metalloenzyme (meaning it carries a metal atom to help it do chemistry) which uses hydrogen peroxide to induce a chemical change in a variety of substrates. This protein, found in high concentrations in horseradish roots, is vital to laboratory science - especially in the context of a test called ELISA. In this test, an antibody chemically linked to an HRP molecule is added to a solution, and allowed to bind to a protein-coated surface. A chemical marker is then added to the solution. This is where HRP comes in: if the antibody successfully bound to the surface, the attached HRP will begin to process the chemical marker, inducing a color change. After a certain amount of time, the reaction is stopped with a strong acid or base, and the color change is measured. More color change in the given timeframe corresponds to more HRP-antibodies bound to the surface. This, in turn, tells you how strong the interaction is between your antibody and the surface-bound protein! ELISA tests are used in labs that study proteins, but they are probably familiar to most people as the tests used to detect diseases like HIV in the bloodstream. Thanks to horseradish for doing its part to fight disease!


Oct. 1, 2018

Many of the foods we eat contain a large number of polysaccharides. These molecules go through many metabolic processes within us to produce glucose. The glucose is then transported from the extracellular space into cells where it is used to generate ATP- which is the energy that our bodies use to carry out work. The real trick here is getting glucose through the cell membrane. Two important molecules play a role in this process. The first is insulin which is released from pancreatic Beta cells when there is an increase in glucose concentration. The second is the insulin target receptor (pdb:4ZXB) and this week’s featured molecule; Insulin Receptor (IR). IR is a subtype receptor of the tyrosine kinase family, which is also activated by IGF-1 and IGF-2. Once insulin binds to IR a cascade of events occurs via the PI-3K signaling pathway which causes the insertion of GLUT-4. GLUT-4 is the glucose transporter that walks glucose across the cell membrane. As you can see, insulin receptor is very important and errors in the receptor or the signaling pathway can be fatal if not treated promptly. A common pathology that causes problems with this pathway is diabetes mellitus type 2. In this form of diabetes there is an insulin resistance to some of the IR in the body. Patients with type 2 diabetes suffer from an elevated plasma glucose level which may lead to glycosuria and ketoacidosis. Treatment for type 2 diabetes involves an individual making lifestyle changes, self-monitoring blood glucose levels, and taking certain medications.