Читать книгу Plant Nucleotide Metabolism - Hiroshi Ashihara - Страница 62

The last two steps to form IMP, the first complete purine nucleotide, are catalysed by the bifunctional enzyme 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase (EC 2.1.2.3)/inosine monophosphate cyclohydrolase (EC 3.5.4.10) (abbreviated as ATIC). In the first part of this reaction the final carbon of the purine ring is provided by 10-formyl-THF to form 5-formamidoimidazole-4-carboxamide ribonucleotide (FAICAR) (step 9, Figure 4.1, Reaction 9). FAICAR then undergoes dehydration and ring closure to generate IMP (step 10, Figure 4.1, Reaction 10).