A Simple Method to Explore Enzyme Activity
by Brad Williamson
Enzymes are essential in nearly all life processes. By catalyzing (speeding up a chemical reaction) various chemical reactions in the cell enzymes make energy and nutrients available to living systems. Each enzyme only catalyzes one kind of chemical reaction so there is a lot of enzymes in a typical cell. As the human genome project uncovers the genes in the human population it is important to realize that many of the genes code for enzymes. A basic understanding of enzyme properties then is an essential, first step, to understanding living systems.
Enzyme studies are easily studied by students. For this investigation we will work with an enzyme that begins the breakdown of starch into sugar. It’s called amylase (enzyme) since it breaks down starch (the substrate) which is known as amylose. Scientists use the term substrate to describe the chemical that an enzyme catalyzes. Starch is an energy-storing compound present in many plant foods such as potatoes, corn and bread. Amylase is a component of saliva where it starts the digestion of starch as you chew your food. It’s also a valuable commercial enzyme. The starch in grains such as sorghum are digested with amylase in large reaction vessels to break the starch down to sugar which is then used to produce a number of products. Quite a bit of research that is done by various agricultural product companies attempts to find more efficient forms of enzymes such as amylase. Any organism that might consume starch (including plants) probably relies on some form of this enzyme. And each organism might have just a slightly different form of the enzyme that might be more efficient than others. You might find such an organism and find a valuable enzyme product.
Most of the time biochemists (scientists that study enzymes) work with enzymes in a liquid environment. Such techniques require careful control of a number of variables. A simpler method to study enzymes involves a gel-like substance known as agar. The substrate (starch in this case) is dissolved in this gel and various suspected enzyme-containing substances are added to small holes (wells) in the gel. The suspected enzyme diffuses out through the gel. If it can actively digest starch it will create a starchless area around the well. Iodine stain can be used to cause starch to turn a dark purple. Clear zones that are not purple are areas that the enzyme has digested the starch to sugar. This technique makes it simple to test many samples for activity or to determine the amount of activity a specific enzyme might have. In addition, it is easily modified to test various variables that might affect enzyme activity.
You’ll find the entire lab in pdf format for downloading here: A Simple Method to Explore Enzyme Activity