RESUMO
The mechanism of ATP biosynthesis from adenine was studied on the cell-free extract of Corynebacterium species that produces ATP from exogenous adenine, using labeled substrates. As a source of the ribosyl component of the ATP molecule, phosphoribosyl pyrophosphate (PRPP) and ribose-5-phosphate (P5P) were tested. The experiments with PRPP showed adenine phosphoribosyl transferase (EC 2.4.2.7) activity in the extract responsible for the AMP formation from PRPP and adenine. The minimal reaction mixture based on R5P was found to include only magnesium ions, in addition to R5P, adenine, and the extract. This mixture provided the synthesis of not only C14-AMP but also C14-ADP and C14-ATP from C14-adenine. Phosphorylation of C14-AMP to yield C14-ATP was related to the presence of R5P in the mixture. The synthesis of C14-ATP from C14-adenine also took place when R5W was substituted for glucose in the minima mixture.
