 Consequently, most organisms have efficient systems to salvage preformed nucleotides.Purines are synthesized as nucleosides (bases attached to ribose).Both adenine and guanine are made from the precursor nucleoside inosine monophosphate, which is synthesized using atoms from the amino acids glycine, glutamine, and aspartic acid, as well as formate transferred from the coenzyme tetrahydrofolate.