Purine metabolism in the bloodstream forms of Trypanosoma gambiense and Trypanosoma rhodesiense.

Bloodstream forms of Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense are incapable of de novo purine synthesis. Purine bases are converted directly to ribonucleotides and with the exception of guanine, are stable. Guanine is incorporated directly into ribonucleotides and also deaminated to xanthine. Purine ribonucleosides are hydrolyzed rapidly; these reactions may limit their incorporation since purine bases label the nucleotide pools more efficiently than do ribonucleosides. The apparent order of salvage efficiency for ribonucleosides is adenosine greater than inosine greater than guanosine greater than xanthosine for both organisms. T. b. gambiense salvages purine bases in the same order, while T. b. rhodesiense salvages purine bases in the order hypoxanthine greater than adenine greater than guanine greater than xanthine.