EK Kinetigram Exercise 1.

Question 1.
In the beginning of the movie located in Panel 1 (click on the button 'EK Java Kinetigrams'), k1 is changing (the rate constant for the first reaction), while all the other parameters are kept constant: S0 = 1, E0 = 0.4, r1 = 0.1, and k2 = 0.1.
(1) As k1 increases, what is happening to the substrate concentration S(t) and the product concentration P(t)?
 
 
 
 
 
 

(2) As k1 increases, what is happening to the enzyme concentration E(t) and the concentration of the enzyme-substrate complex C(t)?
 
 
 
 
 
 

(3) Explain your observations in (1) and (2) in terms of the reactions involved. Why does this make sense?
 
 
 
 
 
 

Question 2.
In the 2nd part of the movie located in Panel 1 (click on the button 'EK Java Kinetigrams'), r1 is changing (the rate constant for the reverse of the first reaction), while all the other parameters are kept constant: S0 = 1, E0 = 0.4, k1 = 0.1, and k2 = 0.1.
(1) As r1 increases, what is happening to the substrate concentration S(t) and the product concentration P(t)?
 
 
 
 
 
 

(2) As r1 increases, what is happening to the enzyme concentration E(t) and the concentration of the enzyme-substrate complex C(t)?
 
 
 
 
 
 

(3) Explain your observations in (1) and (2) in terms of the reactions involved. Why does this make sense?
 
 
 
 
 
 

Question 3.
In the 3rd part of the movie located in Panel 1 (click on the button 'EK Java Kinetigrams'), k2 is changing (the rate constant for the second reaction), while all the other parameters are kept constant: S0 = 1, E0 = 0.4, k1 = 0.1, and r1 = 0.1.
(1) As k2 increases, what is happening to the substrate concentration S(t) and the product concentration P(t)?
 
 
 
 
 
 

(2) As k2 increases, what is happening to the enzyme concentration E(t) and the concentration of the enzyme-substrate complex C(t)?
 
 
 
 
 
 

(3) Explain your observations in (1) and (2) in terms of the reactions involved. Why does this make sense?
 
 
 
 
 
 

Question 4.
In the movie located in Panel 3 (click on the button 'EK Java Kinetigrams' and then click on the 'Panel Down' button), the initial E to S ratio = E0/S0, where E0 is the initial concentration of E, and S0 is the initial concentration of S. Also, notice that E0/S0 is changing with a resultant change in the percentage of substrate S converted to product P.
(1) What is the percentage of substrate S converted to product P for each of the following values of E0/S0: 0.6, 0.5, 0.4, 0.3, 0.2?
 
 
 
 
 

(2) Describe the relationship observed in (1). What is going on?
 
 
 
 
 
 

(3) Try to explain the following statement using your observations in (1) and (2): "enzyme-catalyzed reactions are rate-limited by enzyme saturation."
 
 
 
 
 
 

(4) At what value(s) of E0/S0 is the velocity function for the enzyme-substrate complex, C'(t), changing the least during the time period: 10s < t < 200s ?