Читать книгу Plant Nucleotide Metabolism - Hiroshi Ashihara - Страница 39

In addition to the non-specific nucleoside-monophosphate kinase mentioned above, there are at least three nucleoside-monophosphate kinases which contribute to the conversion of NMP to NDP. They are adenylate (AMP) kinase (EC 2.7.4.3), guanylate (GMP) kinase (EC 2.7.4.8) and cytidylate (UMP/cytidine-5′-monophosphate [CMP]) kinase (EC 2.7.4.14). It has been reported that genes encoding adenylate kinase show high sequence homology with those encoding UMP-CMP kinase (Fukami-Kobayashi et al. 1996). The equilibrium constants of these enzymes are ∼1, so the reaction is reversible. Adenylate kinase is ubiquitous and is found in different subcellular locations, including the cytosol, mitochondria, and plastids of plants. The reactions of each enzyme, and associated references, are presented in Table 3.1.