Page 204 - Color Atlas of Biochemistry

Porphyrin Metabolism 195

A. Degradation of heme groups

Heme Cleavage by 1
3 N A 3 N A CO R 2 CH 3
P P
H C A B R 3
3
N N
2 1 2
Fe
N N
3 O 2 3 H O Fe 2 R 1 D C CH 3
2
Heme Reused
for heme
synthesis COO COO

Biliverdin
CH 2 OOC CH H C COO CH 2
2
2
CH 3 CH CH 3 CH 2 CH 2 CH 3 CH 3 CH

N A N A
B C D A
P P
O N C N C N C N O
H H H H 2 H H H
Bilirubin
2

Bilirubin RES
Bilirubin 3 Bilirubin
diglucuronide Urine
U
2 P P GlcUA 2 UDP Slowest
Blood step in
Albumin hepatic
metabo-
lism
Gallbladder

Entero-
Albumin hepatic
Bile circulation
Bilirubin pigments

Intestine
Binding
site for
bilirubin
and drugs Bilirubin Bacterial
metabolism
diglucuronide
2 GlcUA

1 Heme oxygenase Stercobilinogen
(decyclizing) 1.14.99.3 Bilirubin Urobilinogen

2 Biliverdin reductase
1.3.1.24
Stercobilin
3 Glucuronosyl Urobilin
transferase 2.4.1.17

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