Page 126 - Color Atlas of Biochemistry

Metabolic Regulation 117

A. Aspartate carbamoyltransferase: reaction

COO C
PP P
L-Aspartate CH 2
CTP CTP
C
H N H COO COO
3
Aspartate H N CH 2
2
carbamoyl- UMP
CO 2 NH 2 transferase C C
R-NH 2 C 2.1.3.2 [ Zn ] O N H COO
2
ATP O H
P P
N-Carbamoyl
N-Carbamoyl– P L-aspartate
A
PP P ATP

B. Kinetics C. R and T conformation

7 Active C 1 C 3
center C 2
6
2 mM ATP III R' 1 R' 2
h = 1.4
5 R 1
Activity 4 Effector- C 4 C 5 C 6 R 2
binding
[A] 0.5 I Without site
effector
h = 2.0 T conformation
3
(less active)
2 II 0.5 mM CTP
h = 2.3
1 C 2
C 1 C 3
0 R' 1 R' 2
0.0 5.0 10.0 15.0
R 3
[Aspartate] (mM)
R 1 R 2
C 4 C 6
D. Structure of a dimer C 5
R conformation
(more active)

Substrate Regulatory
subunit

ATP (CTP)

Catalytic
2
subunit Zn domain ATP/CTP-binding domain

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