Page 97 - General Biochemistry

Figure 20 synthesis of IMP

• The first step is the production of 5-phospho-α-D-ribosyl 1-pyrophosphate
(PRPP) from R5P by ribose phosphate pyrophosphokinase enzyme,
Activators of this step: inorganic phosphate
Inhibitors: purine ribonucleotides.
Why this step is not considered the committed step to purine synthesis?

• The second step is called a committed step in which the reaction of PRPP,
glutamine and water to give 5'-phosphoribosylamine (PRA), glutamate, and

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