Introduction
Enzymes are proteins that function as biological catalysts, which increase the rate of reaction without being destroyed themselves by it (Campbell, et al., 2008). Since not all chemical reactions are fast acting, the slower reactions need a “boost” and that is where enzymes come in. A major process that occurs within our bodies is metabolic process, which tends to be a slower reaction. If metabolic process occurs at its normal slow rate than many cells would die. Thus, the vital role of enzymes is key for slow acting processes naturally occurring in our bodies.
Enzymes are substrate-specific, meaning that only a particular substrate can react with the enzyme to make a product. The given substrate fits into a region of the enzyme called the active site. The active sites act like a “pocket” for the substrate. In this particular lab the enzyme being used was tyrosinase, which is found in many organisms including humans.
All enzymes have an active site, and an enzyme is “available” when the active site is empty. Then comes the substrate, which binds to the enzyme in the active site. With some enzyme-substrates hydrolysis occurs, but it may not always be the case. After, the substrate is converted into products. Then, the products are released. There is a huge turnover count for products because this cycle occurs in the thousands range per second.
The three main environmental factors that affect enzyme activity are temperature, pH, and substrate concentration. Temperature and pH are components of homeostasis, which help keep our bodies’ cells in equilibrium. As the bodies temperature increases so does the enzyme activity. Then at about 37° Celsius enzyme activity reaches its optimum, which also happens to be the bodies average temperature. After the optimum point, the enzyme activity begins to drastically decrease. Enzymes tend to be hypersensitive to high temperatures, because it is at this point that they tend to denature, or “unwind.” The two main things that cans cause the denaturing of enzymes are the severity and duration of the heat. Enzymes can be renatured if the temperature decreases back to body temperature.
Tyrosinase is a naturally occurring enzyme in plant cells. This particular enzyme causes the brownish coloring from bruises in fruits and vegetables. At the site of “injury” tyrosinase reacts with pyrocatechol (a substrate) to then form hydroxyquinone. In this particular lab, the tyrosinase comes from potato cells (Couch and Beger, 2004).
The control experiment tested four different combinations of enzymes and substrates. The first was the enzyme tyrosinase and the substrate pyrocatechol and the second was just the substrate pyrocatechol. The third test tube had just the enzyme tyrosinase, and the last test tube had the enzyme tyrosinase and the substrate sucrose. Temperature was the experiment being tested by the group. There were four environmental temperatures in which the enzymes were exposed to, ranging from cold to hot water baths.
