Page 34 - Color Atlas of Biochemistry

Physical Chemistry 25

A. Catalysis: principle

Substrates Products Substrates Products

∆G E a ∆G E 1 E 2
a
a
1. Energy profile without catalyst 2. Energy profile with catalyst

B. Catalysis of H2O2 – breakdown by iodide

H O 2 + H O 2 O 2 + H O + H O
2
2
2
2
1. Breakdown of hydrogen peroxide

Uncatalyzed reaction H O 1a Atomic oxygen 1b H O 2
2
2

O
2
Catalyst (iodide)

H O
H O 2 2
2
Catalyzed reaction 2a 2b O 2

H O Hypoiodide
2
2
2. Catalyzed reaction H O 2

Relative velocity 1300000000
Uncatalyzed Iodide Catalase
100
H O 2
2
E a
80 2100
E a (kJ · mol -1 ) 60 E a Heme

40
E a
20

1
3. Activation energies Active center of catalase

Koolman, Color Atlas of Biochemistry, 2nd edition © 2005 Thieme
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