Nucleoside phosphotransferase, a unique purine salvage enzyme of proto
zoa Leishmania tropica, was partially purified. The purified sample wa
s nucleosidase free. With this enzyme preparation, phosphorylation of
14 nucleosides involving 5 antileishmanial purine nucleoside analogs w
as investigated. Apparent Km values of the enzyme for the 10 purine nu
cleosides were in the range 5.7-8.4 mu M, and those for the 4 natural
pyrimidine nucleosides were 14.0-16.9 mu M.