where does de novo synthesis of purine occur
De novo synthesis De novo pathways do not use free bases: adenine (abbreviated as A), guanine (G), cytosine (C), thymine (T), or uracil (U). The purine ring is built up one atom or a few atoms at a time and attached to ribose throughout the process. Pyrimidine ring is synthesized as orotate and attached to ribose phosphate and later converted to common pyrimidine nucleotides. De novo synthesis enzymes are predicted to be present as large multienzyme complexes, although this hypothesis has yet to be thoroughly proven.