Guanosine 5 -phosphate reductase

Guanosine 5-phosphate reductase has been partially purified from extracts of Enterobacteriaceae and carries out the following irreversible reductive deamination reaction 88). 

Fig. 173. Interconversion of inosine, adenosine and guanosine monophosphates 1 Inosine monophosphate dehydrogenase 2 guanosine monophosphate synthase 3 guanosine monophosphate reductase 4 adenylosuccinate synthetase 5 adenylosuccinate lyase 6 adenosine (phosphate) deaminase...

The deoxyribonucleotides are derived primarily, if not entirely, by reduction of ribonucleoside phosphates each of the several known ribonucleotide reductases (see Chapter 16) accepts as substrates phosphate esters of all four ribonucleosides, adenosine, guanosine, cytidine, and uridine. The ultimate fate of the uracil-containing reduction product, dUDP (or dUTP, in some microorganisms) is conversion to thymidine phosphates by way of deoxyuridylate and the thymidylate s mthetase reaction. 

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