Page 196 - Color Atlas of Biochemistry

Nucleotide Metabolism 187

A. Degradation of nucleotides

1. Purine nucleotides 2. Pyrimidine nucleotides

GMP AMP UMP CMP dTMP
P P PRPP
G A U C T
P P P P P

H O H O
2
2
2
1 P NH 3 Uracil Thymine
Free
Ade IMP Ura Thy
G I bases
Adenine P N A N A
P P
P
N A N A
O
Rib P P P R P
C
PRPP 1 Dihydro- HN C H Dihydro-
Gua Guanine I uracil C CH thymine
(R = CH )
(R = H)
O N 2 3
Phospho- H O P H
2
ribosyl H O H O
2
2
diphos-
phate NH 3 Rib P PRPP COO
H N H C R N-Carbamoyl
2
O O 2 O N-Carbamoyl β-amino-
H O β-alanine C CH 2 isobutyrate
2 2 H O
C N 2 C N (R = H) O N (R = CH )
HN C HN C H 3
CH 3 CH H O H O
C C HC C 2 2
O N N N N
H H H NH , COO NH ,
Xanthine (Xan) Hypoxanthine (Hyp) CO 2 3 H C R CO 2 3
O 2 CH 2 β-Amino-
H O 3 β-Alanine NH isobutyrate
2
(R = H)
(R = CH )
H O 3 3
2 2 Excreted
by primates, B. Hyperuricemia (gout)
O birds, and
H reptiles Causes:
C N 2a
HN C Disturbed uric
C O 1
C C acid excretion
O N N Uric acid GMP AMP Elevated uric acid
H H 2 formation
Excreted 2b 2b a) Unbalanced
by most a) nutrition
O H mammals
H N C N Gua Ade IMP b) Impaired
2
C O b) recycling of
C C b) purine bases
O N H N 2b
H H Allantoin Hypo-
Xanthine Recycling
xanthine reactions
Allantoic acid 2 Urea +
glyoxylate O
Allopurinol H
C C
1 Hypoxanthine phosphoribosyl- HN C
transferase 2.4.2.8 Uric 1 N
Adenine phosphoribosyl- acid HC C N
2 N
transferase 2.4.2.7 H
3 Xanthine oxidase [Fe, Mo, FAD] 1.1.3.22 Allopurinol

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