Lesch-Nyhan Disease

One Enzyme

Background:

This is a very rare disorder that is interesting because of the extensive effects caused by a simple deficiency in one enzyme. The most disturbing result of the loss of this one enzyme is that affected individuals engage in many self-mutilative behaviors. Patients often chew off their lips and bite their cheeks and fingers until severely damaged.

Activity:

As the class is learning about enzymes and the roles they play in our bodies, it is important to emphasize how every enzyme serves a very important and functional role. The loss of even a single enzyme can have enormous implications. Lesch-Nyhan is one example of some of those severe implications. Albinism and many other traits are examples of disorders derived from the loss of a single enzyme.

An enjoyable lab activity involves hydrogen peroxide and potatoes. Potatoes (and all living things) contain an enzyme (hydrogen peroxidase) that breaks down hydrogen peroxide into hydrogen and oxygen. If one takes a potato slice and pours hydrogen peroxide on it, it will start to bubble as the hydrogen and oxygen are released. Show this to your class in a demonstration. Then allow them to design their own lab activity to observe other ways hydrogen peroxidase works. Some students may want to see if hydrogen peroxide causes bubbling in other items like leaves, grass or other food products. Some students may want to find out if the hydrogen peroxide will bubble after a potato has been cooked or frozen. (Heat causes the enzyme to denature and the reaction will not occur.) Some students may wonder if there are other substances (besides hydrogen peroxide) that will produce a reaction when placed on a slice of potato. Allow the class members freedom to explore this in whatever safe way they may want. Teachers should swerve as a guide, directing them, but not instructing them in what to do.

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