The biochemical characterization of two phosphate transport systems in Phytomonas serpens.

Inorganic phosphate (P) is an essential nutrient for all organisms because it is required for a variety of biochemical processes, such as signal transduction and the synthesis of phosphate-containing biomolecules. Assays of P uptake performed in the absence or in the presence of Na indicated the existence of a Na-dependent and a Na-independent P transporter in Phytomonas serpens. Phylogenetic analysis of two hypothetical protein sequences of Phytomonas (EM1) showed similarities to the high-affinity P transporters of Saccharomyces cerevisiae: Pho84, a Na-independent P transporter, and Pho89, a Na-dependent P transporter.

Leishmania amazonensis: inhibition of 3'-nucleotidase activity by Cu2+ ions.

Free Cu(2+) is toxic due to the capacity of free copper ions to catalyze the production of reactive oxygen species (ROS) that can modify the structure and/or function of biomolecules. In addition, non-specific binding to enzymes, which modifies their catalytic activities, can occur. In this work, the mechanisms underlying the ability of copper to inhibit 3'-nucleotidase from Leishmania amazonensis (La3'-nucleotidase) were investigated.

Leishmania amazonensis: characterization of an ecto-3'-nucleotidase activity and its possible role in virulence.

Ecto-3'-nucleotidase/nuclease (3'NT/NU) is a membrane-bound enzyme that plays a key role in the nutrition of Leishmania sp. protozoan parasites. This enzyme generates nucleosides via hydrolyzes of 3'mononucleotides and nucleic acids, which enter the cell by specific transporters.