Pathways of nucleotide metabolism in schistosoma mansoni—IV: Incorporation of adenosine analogs in vitro

Abstract

The incorporation in vitro of adenine or adenosine analogs into schistosome nucleotides is demonstrated. Tubercidin, 2-fluoroadenosine and 2-fluoroadenine were all shown to be converted into analog triphosphate nucleotides. Since tubercidin and 2-fluoroadenosine are not substrates for adenosine deaminase or purine nucleoside phosphorylase and are not susceptible to degradation to the free base level, it is assumed that they are converted to nucleotides by reaction with adenosine kinase. The incorporation of 2-fluoroadenine into the nucleotide pools indicates that it serves as a substrate for adenine phosphoribosyltransferase. Tubercidin, added to the culture medium, interferes with the maintenance of normal ATP levels. When the concentration of the analog greatly exceeded that of adenine or adenosine in the medium, virtual shutdown of adenosine triphosphate synthesis followed. It is suggested that stoichiometric competition for enzyme sites may determine the relative amounts of nucleotides formed.