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!