Physical Chemistry 3: — Chemical Kinetics — - Christian-Albrechts ...

10.1 Kinetics of enzyme catalyzed reactions (homogeneous catalysis) 217
I
Figure 10.2: Lineweaver-Burk plot.
10.1.2 Inhibition of enzymes:
Extended reaction mechanism:
E+S 1
À ES (10.29)
−1
ES 2
→ E+P (10.30)
E+I 3
À EI (10.31)
−3
The EI complex is catalytically inactive, since I blockstheactivesiteofE.
Inhibition constant:
= [EI]
[E] [I] = 3
−3
(10.32)
I
Reaction rate (Fig. 10.2):
y
[ES]
= ≈ 0 (10.33)
1
= 1 +(1+ [I]) ×
1
(10.34)
2 [E] 0
2 [E] 0
[S] 0
y The slope of the plot of −1 vs. [S] −1 0
goes up (see Fig. 10.2).
Exercise 10.1: Derive Eq. 10.34 with a reasonable assumption for the concentrations
of I. ¤