Question

Which molecules contribute the nitrogen atoms for purine biosynthesis and which reactions in the de novo synthesis of purine nucleotides require energy expenditure?

Answer 1

Answer:

Q) Which molecules contribute the nitrogen atoms for purine biosynthesis and which reactions in the de novo synthesis of purine nucleotides require energy expenditure?

• For purine biosynthesis, Nitrogen is contributed by amino acid glycine, glutamine and asparatic acid.
• The reaction in the denovo synthesis of purine nucleotides that require energy expenditure is the conversion of ribose-5-P into phosphoribosyl pyrophosphate (catalyzed by Pyrophospho Kinase). This reaction consumes ATP.
• Another reaction where ATP is consumed is the conversion of Formyl Glycine ribotide into Formylglycinaidine ribotide (FGAM) (catalyzed by enzyme FGAM synthetase).  
• The conversion of FGAM into 5-amino imidazole ribotide (AIR) (catalyzed by AIR Synthetase) also requires ATP.