Incorporation of Radioactivity from (5-amino-4-carboxamido-2-14c-imidazole)adenine Dinucleoside Pyrophosphate into Nucleic Acids.

It was previously demonstrated that in the presence of beef spleen nicotinamide adenine dinucleotide glycohydrolase, 4(5)amino-5(4)-carboxamidoimidazole reacted irreversibly with nicotinamide adenine dinucleotide to form the pyrophosphate of adenosine 5’-phosphate and of 5(4)-amino-(4)5-carboxamidoimidazole ribonucleotide (i.e. the (5-amino-4-carboxamidoimidazole)adenine dinucleoside pyrophosphate (1)) (Fig. 1). This dinucleoside pyrophosphate was later converted to hypoxanthine adenine dinucleoside pyrophosphate by semipurified liver extracts (2). Such conversions established the possibility of purine biosynthetic reactions occurring at the dinucleoside pyrophosphatel level. The availability of labeled IAD in substrate quantities at a time when other dinucleoside pyrophosphates were not as readily available in our laboratory3 suggested a study of the incorporation of radioactive material from IAD into nucleic acids. A description of these experiments is reported in this paper.