Nucleic Acids in Chemistry and Biology

Nucleosides and Nucleotides 123

N

HN N

N

H

O

N H 2 N

HN N

N

H

O

N

H

HN N

N

H

O

O

N

HN

N

N

H

O

N

H

HN

H

N

N

H

O

O

O

GMP

adenosine inosine guanosine

5'-nucleotidase 5'-nucleotidase 5'-nucleotidase

adenosine deaminase

adenylate deaminase

Pi

ribose

1-α-phosphate

Pi

purine

nucleotide

phosphorylase

purine

nucleotide

phosphorylase

hypoxanthine guanine

xanthine uric acid

allopurinol

xanthine

oxidase

xanthine

oxidase

ribose

1-α-phosphate

AMP IMP

Figure 3.82 Catabolism of purine nucleotides

O

HO

O P O

O

O

N

NH

O

O

O

O

HN

O

N

N

HO

N

H 2 N N

H

N

O

O

H 2 C

O

HO

O P O

O

O

N

NH

O

O

H 3 C

O

O

HN

O

HN

N

HO

N

H 2 N N

H

N

O

O

dUMP N^5 , N^10 -methylenetetrahydrofolate

thymidylate

synthase

dTMP dihydrofolate

Figure 3.81 Formation of dTMP from dUMP