1. Lab 7 An Investigation of Enzymes and the Rate of Reactions Using a
Lab 7 An Investigation of Enzymes and the Rate of Reactions Using a Model System (Toothpickase)

2. Enzymes are biological catalysts that are able to induce substrates to react. Substrates will not react without an enzyme lowering the activation energy requirement of the reaction so that it can proceed with the ambient energy of the organism. Substrates must physically fit into the enzyme’s active site where bonds are stressed to the point that they will break and reform using available energy. Enzymes themselves are not changed in the chemical reaction.

3. Enzyme reaction rates for three different enzymes: A, B and C
Regulation of chemical reactions in organisms (the process by which the right chemical reactions proceed in the right place at the right time at the right rate) is performed by enzymes in numerous ways. One way is to modulate the concentration of enzyme…  no enzyme = no significant reaction - if the enzyme is not made by the cell the reaction will not take place
What is happening during the different phases of the reaction?
Enzyme rate reaction graph
What does the line plateau represent?
Enzyme reaction rates for three different enzymes: A, B and C
Constant enzyme and substrate concentration

4. Regulation of chemical reactions
 the more enzyme the faster the reaction
- by “faster the reaction” we mean the faster a given concentration of substrate is converted into product
- because the reaction is a physical process this takes time
- the higher the enzyme concentration, the more active sites available to do the work
How is this graph different from the previous one?
What does “rate of reaction” mean?

5. What does “rate of reaction” mean? Product per time
Do some enzymes work faster than others? What is Vmax?
Vmax = as fast as a given concentration of enzyme can work (maximum velocity); excess of substrate at Vmax
Vmax = maximal product per time for a given enzyme concentration
Vmax = fastest reaction rate for a given enzyme concentration
How is this graph different from the previous one?
For a given enzyme concentration
Reaction velocity = product per time
Vmax increases with increasing enzyme concentration

6. Increasing Vmax with increasing enzyme concentration
The more enzyme the faster the reaction
Vmax plotted for each enzyme concentration

7. On this graph where is Vmax for enzymes A, B and C?
Enzyme reaction rates for three different enzymes: A, B and C
Constant enzyme and substrate concentration

8. V max = portion of graph where slope is steepest Rise over run
Vmax = maximal product per time for a given enzyme concentration

9. V max = portion of graph where slope is steepest
What does this mean for the enzyme?
All active sites of enzymes are saturated

10. Can we demonstrate an enzyme mediated reaction using common objects?
Can we establish a Vmax for our demonstration?
Can we demonstrate some ways enzyme reaction rates (Vmax) can be altered in living systems?
TOOTHPICKASE!!!

11. In this lab your hands will represent the enzyme
Toothpickase
In this lab your hands will represent the enzyme
We will begin with a constant enzyme and substrate concentration
What does our reaction rate graph look like? Where is Vmax?

12. Then we will alter conditions, modeling different ways that enzyme reaction rates can be affected Temperature Competitive inhibitors Allosteric regulation