Purines · reaction 1 of 2

Ribose 5-phosphate + ATP → PRPP + AMP

PRPP synthetase EC 2.7.6.1

Activates the ribose supplied by the pentose phosphate pathway by hanging a pyrophosphate on it. The resulting PRPP is the common currency of every nucleotide: purines, pyrimidines and the salvage pathways too all start from here.

irreversible
Cytosol

in depth

ΔG°′: not documented
Cofactors: Magnesium
Location: Cytosol

Fun fact

Here ATP does not give up one phosphate, but both at once. It is one of the few enzymes that transfer a whole pyrophosphate instead of splitting it.

Nelson, D. L. & Cox, M. M. (2021). Lehninger. Principios de bioquímica, 8.ª ed., ch. 22

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PurinesPRPP synthetase

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