Enzyme Reaction Rates Using Toothpickase

ENZYME REACTION RATES USING TOOTHPICKASE

Background:

Enzymes are agents that enhance the rate of reaction while not being consumed in the reaction.

In this activity, your hands will become the enzyme toothpickase. Your substrate is the toothpick. The product is the broken toothpick. When you find a toothpick, you react with it and break it in two. Your goal is to break toothpicks quickly and efficiently while not damaging yourself in the process.

Pre-lab questions:

1. How many subunits does the toothpickase have?

2. Where is the active site?

3. Does the active site need proximity of certain parts in the subunits?

4. What is the substrate? What is the product?

Exercises and Questions:

Position the toothpicks conveniently around yourself, so you can break them quickly and efficiently.

The instructor will time to activate and end the reaction. As quick as you can, break the toothpicks for 180 seconds. The helpers will count the time and separate products at each time points.

Time Points Toothpicks metabolized Rate of reaction (seconds) (Number of products/sec) 0

10 0 – 10 sec:

30 10 - 30 sec:

60 30 - 60 sec:

120 60 – 120 sec:

180 120 - 180 sec:

1. At what stage was the rate of reaction the greatest? 2. Can you do it infinitely faster? Would there be a limit to the rate of enzymatic reaction?

3. What was the reason for slowing down? Would decrease of substrate concentration, e.g. at the end of reaction, affect the rate of reaction?

4. What if you have some look – alike toothpicks mixed in? Would the rate of reaction change? Would the presence of competitive inhibitors in the reaction change the rate of reaction?

5. What if two persons do it together? Would increase in enzyme concentration affect the rate? What if 20 people crowded together to do it? Would the rate increase infinitely along with increased enzyme concentration?

6. What if your one hand was disabled? Why enzymes have optimal pH, temperature and salt concentration? What if two fingers taped together? Would the presence of non-competitive inhibitors in the reaction change the rate of reaction?

7. Would you be able to catalyze without using any fingers? Is active site of an enzyme important?

8. Could you metabolize a nail instead? Will enzymes be able to catalyze a thermodynamically favorable or a thermodynamically unfavorable reaction?