Page 99 - General Biochemistry

Figure 22 nucleotide biosynthesis and degradation

Regulation of biosynthesis of purines:

• GTP is involved in AMP synthesis and ATP is involved in GMP synthesis
• Why PRPP is an important molecule? Because:

– ADP/GDP levels has a negative feedback on Ribose Phosphate
Pyrophosphokinase

– Amidophosphoribosyl transferase is activated by high PRPP levels
• Rate of AMP production increases with increasing concentrations of GTP

while the rate of GMP production increases with increasing concentrations
of ATP

Purine Catabolism and Salvage:

PURINE CATABOLISM

• Purine degradation leads to uric acid which is excreted in the urine
• The catabolism of purines involves the following steps: deamination

reaction, phosphate removal from the nucleoside monophosphates,

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