On the acid phosphatase isoenzymes existing in American Leishmania promastigotes.

1. Two partially purified acid phosphatase activities present in American Leishmania promastigote homogenates were characterized by biochemical methods. 2. One isoenzyme acts preferentially on p-nitrophenyl phosphate, is strongly inhibited by 30 mM alloxan, citrate, maleate, malonate and succinate, and strongly stimulated by 3 mM spermine. Its pI is 4.8. 3. The other isoenzyme acts preferentially on beta-glycerophosphate and is resistant to 30 mM alloxan, citrate, maleate, malonate and succinate and also to 3 mM spermine. Its pI is 5.7. 4. Both acid phosphatase isoenzymes have an optimum pH of 5.2, are tartrate-sensitive and strongly membrane-bound, as shown by differential centrifugation and density gradient equilibration. 5. Both isoenzymes were separated by using homogenates prepared in 2% Triton X-100, differential centrifugation, Sepharose 4B/CL-4B gel filtration, ion exchange chromatography and electrofocusing. After this procedure, they were still contaminated with several different proteins. 6. Purification was around 150-fold, with a 32% yield. 7. When these acid phosphatase activities were measured in total homogenates from 12 different Leishmania isolates, p-nitrophenyl phosphatase specific activity values were quite close; beta-glycerophosphatase-specific activity had around a 2-fold variation. 8. This variation was independent from taxonomic classification or infectivity of susceptible hosts.