It was established [ 1,2] that the first nucleotide, mainly a purine, that is incorporated into the RNA chain in a RNA polymerase reaction, retains its 5’-tri- phosphate group; enzymes were also found that destroy this group [3,4]. It has been shown [5,6] that RNA chains can be initiated not only by nucleo- tide-5’-triphosphates, but also by short oligonucleo- tides whose 3’-OH ends are not phosphorylated. The fact that the RNA polymerase~atalyzed exchange of labeled pyrophosphate with UTP on d(A-T) copolymer is effectively stimulated not only by ATP, but also by ADP or AMP , suggests that the last two nucleotides can initiate RNA synthesis. Conditions have been found  for the so-called abortive initiation in which the product of a RNA polymerase reaction is freed, after fornlation of the first phosphodiester bond, from the enzyme-template complex to accumulate in the reaction medium. We have shown [9 ] that abortive initiation on the d(A-T) copolymer can involve not only a dinucleotide monophosphate complementary to the template, but atso certain other dinucleotide monophosphates whose 5’-nucleoside part is not co~lplementary to the ten~pIate (e.g., CpA or ApA). Accordin~y, we decided to check whether other adenosine derivatives can also participate in abortive synthesis. Here it is shown that adenosine and nucleotide coenzymes such as NAD and FAD can participate in reactions with UTP that occur by an abortive nlechanism on d(A-T) copolymer or on T4 DNA.
Malygin, A. G., & Shemyakin, M. F. (1979). Adenosine, NAD and FAD can initiate template-dependent RNA a synthesis catalyzed by Escherichia Coli RNA polymerase. FEBS Letters, 102(1), 51–54. https://doi.org/10.1016/0014-5793(79)80926-6