Trypanosoma rangeli is a digenetic hemoflagellate widely distributed in Central and South America, infecting wild and domestic mammals as well as humans. This parasite co-exists with T. cruzi, the agent of Chagas disease, in the Northern part of South America, posing some problems for diagnosis.
Ecto-phosphatases are enzymes that present your catalytic site faced to external medium and have been detected in several microorganisms. Several reports show that surface phosphatase activities can be modulated by the environmental phosphate concentration and this fact becomes relevant to study these enzymes in response to phosphate starvation.
The subject of this study is to characterize phosphatase activities present on the cell surface of T.rangeli maintained in low- and high-phosphate culture medium. We observed that the phosphatase-starvation can modulate the ecto-phosphatase activity from T. rangeli, since cells maintained at the high-phosphate culture medium present hydrolytic activity of 5,98 ± 0,48 nmols p-NP x h-1 x 10-7 cells and that maintained at low-phosphate show an increase of 5-fold. In addition, phosphatase from cells growth at high-phosphate medium present higher substrate affinity, with kinetic parameters of Km 0,5 mM p-NPP and Vmax 21,4 nmols p-NP x h-1 x 10-7 cells, than the cells growth at low-phosphate medium, with kinetic parameters of Km 3,3 mM p-NPP and Vmax 129,13 nmols p-NP x h-1 x 10-7 cells. The sensitivity of the phosphatases to the phosphate inhibition was higher to the cells maintained at high-phosphate culture medium (70% versus 30%, being these inhibitions percentages obtained at 10mM Pi).
We also observed that there are an alkaline and other acid phosphatase activity when the cells was incubated in low- phosphate culture medium while the extracellular pH not influenced the activity of the cells incubated in high-phosphate culture medium.
These results gave to us support to speculate that T. rangeli ecto-phosphatase activities can be modulated by the exogenous phosphate content and these activities are result of different enzymes.
Supported by CNPq, CAPES and FAPERJ.