Purine synthesis

• purine rings are built right on phosphoribose (which comes from PRPP made from ATP)
• regulated steps of purine synthesis include: PRPP synthesis from R5P, attachment of NH3 to PRPP, and the first steps of making AMP and GMP from IMP
• themes seen again include

  • using ATP for attachment
  • glutamine as a source of amino groups
  • attaching aspartate and removing fumarate
  • using THF, this time for formyl groups
• must first create IMP, and then make either AMP or GMP (which are regulated by GTP and ATP respectively)