Purine interconversions in the Australian termite, Nasutitermes walkeri hill

Abstract

Purine interconversions leading to urate synthesis were studied over 60 min in isolated fat bodies from freshly collected Nasutitermes walkeri using ¹⁴C-hypoxanthine, ¹⁴C-inosine and ¹⁴C-guanosine. All were taken up, inosine the most efficiently at an initial rate of 0.06 ± 0.009 nmol/min/mg protein. The major purines, nucleosides and nucleotides were separated and examined for radioactivity. Based on uptake data, 1.3% of ¹⁴C-hypoxanthine, 0.3% of ¹⁴C-inosine and 37% of ¹⁴C-guanosine were converted to urate while 3% of the ¹⁴C-guanosine taken up was also salvaged to nucleotides. Feeding experiments with allopurinol showed that there was no significant production of urate via guanine, guanosine and adenosine. Incorporation data indicated the presence of the enzymes purine nucleoside phosphorylase, xanthine dehydrogenase, guanase and that neither inosine nor hypoxanthine could be salvaged.