Enzyme Kinetics: Part 2 | Biochemistry for MCAT PDF Download

 Page 1


Chapter 5 (part 3) 
Enzyme Kinetics (cont.) 
Page 2


Chapter 5 (part 3) 
Enzyme Kinetics (cont.) 
Michaelis-Menton 
• V
max 
• K
m
  
• K
cat 
• K
cat
/K
m 
 
 E + S    ES  E + P 
k
1 
k
-1 
k
cat 
• Vo = Vmax [S] 
      Km + [S] 
      
•V
max 
•K
m 
•k
cat 
•k
cat
/K
m 
Page 3


Chapter 5 (part 3) 
Enzyme Kinetics (cont.) 
Michaelis-Menton 
• V
max 
• K
m
  
• K
cat 
• K
cat
/K
m 
 
 E + S    ES  E + P 
k
1 
k
-1 
k
cat 
• Vo = Vmax [S] 
      Km + [S] 
      
•V
max 
•K
m 
•k
cat 
•k
cat
/K
m 
How do you get values for V
max
, K
m
 and k
cat
? 
• Can determine K
m
 and V
max
 experimentally 
 
• Km can be determined without an absolutely 
pure enzyme 
 
• K
cat
 values can be determined if V
max
 is known 
and the absolute concentration of enzyme is 
known (V
max
 = k
cat
[E
total
] 
 
Page 4


Chapter 5 (part 3) 
Enzyme Kinetics (cont.) 
Michaelis-Menton 
• V
max 
• K
m
  
• K
cat 
• K
cat
/K
m 
 
 E + S    ES  E + P 
k
1 
k
-1 
k
cat 
• Vo = Vmax [S] 
      Km + [S] 
      
•V
max 
•K
m 
•k
cat 
•k
cat
/K
m 
How do you get values for V
max
, K
m
 and k
cat
? 
• Can determine K
m
 and V
max
 experimentally 
 
• Km can be determined without an absolutely 
pure enzyme 
 
• K
cat
 values can be determined if V
max
 is known 
and the absolute concentration of enzyme is 
known (V
max
 = k
cat
[E
total
] 
 
Lineweaver-Burke Plots 
(double reciprocal plots) 
•Plot 1/[S] vs 1/V
o
  
•L-B equation for straight 
line 
•X-intercept = -1/Km 
•Y-intercept = 1/Vmax 
•Easier to extrapolate 
values w/ straight line vs 
hyperbolic curve 
 
Page 5


Chapter 5 (part 3) 
Enzyme Kinetics (cont.) 
Michaelis-Menton 
• V
max 
• K
m
  
• K
cat 
• K
cat
/K
m 
 
 E + S    ES  E + P 
k
1 
k
-1 
k
cat 
• Vo = Vmax [S] 
      Km + [S] 
      
•V
max 
•K
m 
•k
cat 
•k
cat
/K
m 
How do you get values for V
max
, K
m
 and k
cat
? 
• Can determine K
m
 and V
max
 experimentally 
 
• Km can be determined without an absolutely 
pure enzyme 
 
• K
cat
 values can be determined if V
max
 is known 
and the absolute concentration of enzyme is 
known (V
max
 = k
cat
[E
total
] 
 
Lineweaver-Burke Plots 
(double reciprocal plots) 
•Plot 1/[S] vs 1/V
o
  
•L-B equation for straight 
line 
•X-intercept = -1/Km 
•Y-intercept = 1/Vmax 
•Easier to extrapolate 
values w/ straight line vs 
hyperbolic curve 
 
B
B
B
B
B
B
B
0
0.05
0.1
0.15
0.2
0.25
0 1 2 3 4 5 6 7 8 9 10
Vo
[S]
[S] Vo
0.5 0.075
0.75 0.09
2 0.152
4 0.196
6 0.21
8 0.214
10 0.23


V max 
Km 
Km ~ 1.3 mM 
 
Vmax ~ 0.25