GMP and AMP as methyl radical traps in the reaction with pentaamminemethylcobalt(III)

C8 methylation of the title purine nucleotides was achieved in near neutral aqueous solution by reaction with 13C enriched [Co(NH 3) 5(CH 3)] 2+. This cation decomposes upon dissolution in water by release of a methyl radical. The latter was identified by electron spin resonance (ESR) spectroscopy as the PBN/13??H3 adduct (PBN = phenyl-N-tert-butylnitrone). When the purine nucleotide was used in large excess, the efficiency of the trapping by the C8 atom was determined by integration of the 13C NMR signals to be 20-25% for GMP and 15-20% for AMP, respectively, at 37??C. ?? 2004 Elsevier Inc. All rights reserved.