Metabolic flux through the purine salvage pathway in L. donovani. Heavy blue arrows highlight the major flux of substrates through the purine salvage pathway as deduced from genetic and biochemical experiments. The minor activities are represented by black arrows, and the dashed line indicates that the phosphoribosylation of guanine most likely does not occur under physiological conditions in Leishmania. Abbreviations: APRT, adenine phosphoribosyltransferase; HGPRT, hypoxanthine-guanine phosphoribosyltransferase; XPRT, xanthine phosphoribosyltransferase; AK, adenosine kinase; AAH, adenine aminohydrolase; GDA, guanine deaminase; ADSS, adenylosuccinate synthetase; ASL, adenylosuccinate lyase; AMPDA, AMP deaminase; IMPDH, inosine monophosphate dehydrogenase; GMPS, GMP synthase; GMPR, GMP reductase; NH, nucleoside hydrolase; ADO, adenosine; ADE, adenine; INO, inosine; HYP, hypoxanthine; GUO, guanosine; GUA, guanine; XAO, xanthosine; XAN, xanthine.