Question

How many high-energy phosphate bond equivalents are used in the pathway leading from IMP to GMP?

How many high-energy phosphate bond equivalents are used in the pathway that produces GMP from guanine and PRPP by the PRPP salvage reaction?

Please explain if possible.

Answer 1

IMP (Inosine 5'-monophosphate) is the first intermediate in the de-novo pathway in the Purine mtabolism which further splits to form AMP (Adenosien monophosphate) and GMP (Guanosine monophosphate). GTP is consumed in the conversion of IMP to GMP while one molecule of ATP is consumed and supplies energy for GMP synthesis.

Salvage pathway occurs majorly in extrahepatic tissues and account for 90% of daily purine nucleotide biosynthesis. This requires less energy than de-novo pathway for the synthesis of purines. HGPRT stands for the enzyme Hypoxanthine-Guanine phosphoribosyl transferase which catalyze the formation of nucleotides.