Page 104 - Color Atlas of Biochemistry

Enzymes 95

A. pH and temperature dependency of enzyme activity

Proportion BH + Proportion A -

1.0 1.0
BH + A -
Denaturation
Enzyme
0.8 0.8
active
Activity 0.6 BH + AH BH + A - B A - Activity 0.6 Increased
activity due
to temperature
increase
0.4 0.4
BH +
0.2 0.2 A -

Enzyme
0.0 0.0 denatured
4 5 6 7 8 9 10 0 10 20 30 40 50
pH Temperature (°C)

B. Substrate specificity

Asp-189 Substrate (-X-Arg-Y-) Ser-189 Substrate (-X-Phe-Y-)

Ser-195 Ser-195

His-57 His-57
Asp-102 Asp-102

1 Trypsin (3.4.21.4) 2 Chymotrypsin (3.4.21.1)
–X–Y–Arg (Lys)–Z– –X–Y–Tyr (Trp, Phe, Leu)–Z–

C. Bisubstrate kinetics
3. Covalent
intermediate
A 2. EA complex
product E'
X Y X Y
{B}
Z Z
X Y P1 1/velocity
Active center B
Z
1. Free enzyme E

X Y X Y

Z Z
P2 0 2 4
5. EP2 complex 4. E'B complex
1/{A}(mM-1)

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