IB+lab+catecholase

3 Chemistry of Life - 3.1 Chemical elements and water - 3.2 Carbohydrates, proteins and lipids - 3.3 DNA structure - 3.4 DNA replication - 3.5 Transcription and translation - 3.6 Enzymes - 3.7 Cell respiration - 3.8 Photosynthesis - Biochemistry Labs - DNA Labs

**Catecholase**

The brown color, which usually develops when a potato or apple is cut or bruised, is the result of a chemical catalyzed by several enzymes. One of the most important of these enzymes is catecholase (catechol oxidase or polyphenol oxidase). This enzyme is brought into contact with its substrate, catechol, when cells are ruptured and exposure to air (oxygen) resulting in the oxidation of catechol to the brownish colored benzoquinone. This so called “wound reaction” is apparently protective since the quinones are toxic to microorganisms.
 * Introduction**

0.1% Catechol solution (in dropper bottle with dark glass) Distilled water (150 ml plus full dropper bottle) Electric blender Test tubes (2) Test tube rack Dropper bottle for potato extract Beaker (250 ml) Cheese cloth Stirring rods (2) Balance
 * Materials**

1. Prepare catecholase by thoroughly blending potatoes (15 g/100 ml of water) in distilled water. Filter through cheese cloth. Put filtrate in dropper bottle. 2. Fill each of two test tubes 1/4 full (3 ml) of distilled water. 3. Add 10 drops of catechol to each tube. 4. Add 10 drops of potato extract to one tube, label C. 5. Add 10 drops of distilled water to the unlabelled test tube. Mix. 6. Note and record color of each tube at 1-minute intervals for 5–10 minutes.
 * Procedure**

//source: Miller, S. B. 1992. Simple enzyme experiments.//

[|Science And Plants for Schools] has a useful protocol and more information for those developing their own labs
 * Useful links**