Page 98 - Color Atlas of Biochemistry

Enzymes 89

A. Enzymatic activity B. Reaction and substrate specificity

Group
Bond A
. –1
Turnover (mol product s )
without enzyme Group

. –1
Turnover (mol product s ) with enzyme B B B B

. –1
Enzyme activity (mol s = kat) C C C C C C C C

Reaction specificity Substrate specificity
1 Katal (kat): Amount of enzyme A High High
which increases
. –1
turnover by 1 mol s B High Low
C Low Low

C. The enzyme classes

Class Reaction type Important subclasses

= Reduction equivalent
Dehydrogenases
1 Oxidoreductases Oxidases, peroxidases
+ Reductases
+
Monooxygenases
Dioxygenases
A red B ox A ox B red
C 1 -Transferases
Glycosyltransferases
2 Transferases +
+ Aminotransferases
Phosphotransferases
A–B C A B–C

Esterases
3 Hydrolases + Glycosidases
Peptidases
Amidases
A–B H O A–H B–OH
2
C-C-Lyases
C-O-Lyases
4 Lyases + + C-N-Lyases
(“synthases”) C-S-Lyases
A B A–B

Epimerases
cis trans Isomerases
5 Isomerases
Intramolecular
transferases
A Iso-A
B
X=A,G,U,C XDP C-C-Ligases
6 Ligases + X PP P + X P P C-O-Ligases
C-N-Ligases
(“synthetases”) C-S-Ligases
A XTP P
A–B

Koolman, Color Atlas of Biochemistry, 2nd edition © 2005 Thieme
All rights reserved. Usage subject to terms and conditions of license.