Purines in nucleic acids

From these results on may conclude that purines in mononucleotides are absorbed to a larger extent than purines in nucleic acids in the case of 5 -AMP this absorption would appear to be nearly quantitative. 

Abrams and co-workers first showed that the precursors of nucleic acid purines were the same as those of uric acid by demonstrating the incorporation of N -glycine into adenine and guanine of the nucleic acids of growing yeast. Heinrich and Wilson, using the rat, also explored the precursors of purines in nucleic acids, and their results confirmed the earlier observations of Buchanan and collaborators for uric acid. It has now been well substantiated that formate, glycine, and CO2 aU con-... 

The occurrence of methylated derivatives of purines in nucleic acids raises the question of their biological significance. It is possible that methylated purines were incorporated accidentally into nucleic acid and merely replaced natural bases because they were present in the cell for other purposes. The methylated purines may represent constituents of unknown coenzymes or may be vital components of some nucleic acid of specialized function. Also, the possibility should not be overlooked that the methylated purines were not useful to the organism, but represented minor by-products of the usual nucleic acid purines. However, an intriguing possibility has been offered that a methylated base might participate in the template coding of an uncommon amino acid such as cysteine or tryptophan or even act to produce a correct termination of the polypeptide chain 226). 

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