Isolation of plasma membranes of Trypanosoma vivax and studies of adenosine metabolism in different cell fractions

Abstract

This study was designed to isolate the plasma membrane of Trypanosoma vivax and investigate how labelled adenosine is incorporated into other purines (bases, nucleosides and necleotides) in the membrane fraction, intact cells, cell homogenate and supernatant fraction.

      Determination of marker enzyme activities during the purification of plasma membranes of T. Vivax showed that though adenosine triphosphatase (ATPase) activity was present, no sensitivity to oubain or oligomycin was observed.  Activities of 5-nucleotidase, acid phosphatase and glucose-6-phosphatase were detected on the isolated membranes.

      Analysis of the metabolic products of adenosine in intact cells, cell homogenate, supernatant fraction and isolated plasma membranes showed that radioactive adenosine was incorporated into adenine, hypoxanthine, inosine and total nucleotides in the following order of decreasing radioactivity:  inosine < hypoxanthine < nucleotides < adenine.

      Our data suggest that T. vivax has multiple routes of adenosine metabolism and the route taken depends on the concentration of adenosine.

      In vitro assay of enzyme activities provided evidence for the presence of purine nucleoside phosphorylase and adenosine deaminase (among other enzymes of purine salvage) in T. vivax.