Polyamine and thiol metabolism in Trypanosoma granulosum: Similarities with Trypanosoma cruzi

Concentrations of free polyamines were investigated in Trypanosoma granulos um cultured in a semidefined medium containing traces of polyamines. Spermi dine content peaked in early logarithmic growth while putrescine was not de tectable, Unlike African trypanosomes and Leishmania, spermine was measured at equivalent amounts to spermidine in mid to late logarithmic stage cells . Addition of D,L-alpha -difluoromethylornithine to cultures did not decrea se polyamine content nor was ornithine decarboxylase activity detected, in contrast, incubation of parasites with tritiated putrescine showed rapid up take and subsequent conversion to spermidine and spermine. At late logarith mic growth, parasites contained glutathione (77% of total sulphydryl groups ) and ovothiol A as major low molecular mass thiols with glutathionylpolyam ine conjugates undetectable. However, the addition of exogensus putrescine elevated trypanothione and glutathionylspermidine content to 48% of total s ulphydryl groups. Correspondingly, the addition of exogenous cadaverine inc reased homotrypanothione content. This first report of polyamines and low m olecular mass thiols in Trypanosoma granulosum indicates intriguing similar ities with the metabolism of the human pathogen Trypanasoma cruzi. (C) 2001 Academic Press.