Page 110 - Color Atlas of Biochemistry

Enzymes 101

A. Lactate dehydrogenase: catalytic cycle

.
.
.
E H E H NADH
Arg-109
HN NH 2 HN NH 2 NH H
C C 2
C
H N H N O N
2
2
H
Loop H
H 98-111 H H
C N H
C N
HC CH HC CH NADH
N N
H H
His-195 H N NH 2 H N NH 2
2
2
C Arg-171 C
HN HN
1. Free enzyme 2. NADH bound

NH 2 H
HN NH 2 NH 2 H HN NH 2 C
C C O N
C
H N O N H N H
2
2
H H
H H H C H
E . H . NAD C N H H NAD C N H O C Pyruvat E . H . NADH . Pyruvat
3

HC
N CH HC N CH O O
H H N NH 2 H H N NH
2
C 2 C 2
HN HN
6. NAD bound 3. Pyruvate bound

NH 2 H NH 2 H
HN NH 2 C HN NH C
C O N C 2 O N
H N H N H
2
2
H H H C H H
3
H O C H
H C H
3 C N
O O
O C H HC CH
C N Lactate N
H H H N NH
HC CH O O 2 C 2
N Proton Hydride
H transfer HN transfer
H N NH 2
2
C
HN
5. Lactate bound 4. Redox reaction

.
.
E NAD Lactate Transition state

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